From 9a97001cc849038223aa5eda6a76ac0fc6f1094f Mon Sep 17 00:00:00 2001
From: Lorenz Meier <lm@inf.ethz.ch>
Date: Sun, 4 Aug 2013 01:50:58 +0200
Subject: [PATCH 01/11] Added queue to mpu6k driver

---
 src/drivers/mpu6000/mpu6000.cpp | 254 +++++++++++++++++++++++++-------
 1 file changed, 201 insertions(+), 53 deletions(-)

diff --git a/src/drivers/mpu6000/mpu6000.cpp b/src/drivers/mpu6000/mpu6000.cpp
index 1fd6cb17e7..d37d39a7ab 100644
--- a/src/drivers/mpu6000/mpu6000.cpp
+++ b/src/drivers/mpu6000/mpu6000.cpp
@@ -181,13 +181,21 @@ private:
 	struct hrt_call		_call;
 	unsigned		_call_interval;
 
-	struct accel_report	_accel_report;
+	unsigned		_num_accel_reports;
+	volatile unsigned	_next_accel_report;
+	volatile unsigned	_oldest_accel_report;
+	struct accel_report	*_accel_reports;
+
 	struct accel_scale	_accel_scale;
 	float			_accel_range_scale;
 	float			_accel_range_m_s2;
 	orb_advert_t		_accel_topic;
 
-	struct gyro_report	_gyro_report;
+	unsigned		_num_gyro_reports;
+	volatile unsigned	_next_gyro_report;
+	volatile unsigned	_oldest_gyro_report;
+	struct gyro_report	*_gyro_reports;
+
 	struct gyro_scale	_gyro_scale;
 	float			_gyro_range_scale;
 	float			_gyro_range_rad_s;
@@ -306,14 +314,25 @@ private:
 /** driver 'main' command */
 extern "C" { __EXPORT int mpu6000_main(int argc, char *argv[]); }
 
+/* helper macro for handling report buffer indices */
+#define INCREMENT(_x, _lim)	do { _x++; if (_x >= _lim) _x = 0; } while(0)
+
 MPU6000::MPU6000(int bus, spi_dev_e device) :
 	SPI("MPU6000", ACCEL_DEVICE_PATH, bus, device, SPIDEV_MODE3, 10000000),
 	_gyro(new MPU6000_gyro(this)),
 	_product(0),
 	_call_interval(0),
+	_num_accel_reports(0),
+	_next_accel_report(0),
+	_oldest_accel_report(0),
+	_accel_reports(nullptr),
 	_accel_range_scale(0.0f),
 	_accel_range_m_s2(0.0f),
 	_accel_topic(-1),
+	_num_gyro_reports(0),
+	_next_gyro_report(0),
+	_oldest_gyro_report(0),
+	_gyro_reports(nullptr),
 	_gyro_range_scale(0.0f),
 	_gyro_range_rad_s(0.0f),
 	_gyro_topic(-1),
@@ -340,8 +359,6 @@ MPU6000::MPU6000(int bus, spi_dev_e device) :
 	_gyro_scale.z_offset = 0;
 	_gyro_scale.z_scale  = 1.0f;
 
-	memset(&_accel_report, 0, sizeof(_accel_report));
-	memset(&_gyro_report, 0, sizeof(_gyro_report));
 	memset(&_call, 0, sizeof(_call));
 }
 
@@ -353,6 +370,12 @@ MPU6000::~MPU6000()
 	/* delete the gyro subdriver */
 	delete _gyro;
 
+	/* free any existing reports */
+	if (_accel_reports != nullptr)
+		delete[] _accel_reports;
+	if (_gyro_reports != nullptr)
+		delete[] _gyro_reports;
+
 	/* delete the perf counter */
 	perf_free(_sample_perf);
 }
@@ -361,6 +384,7 @@ int
 MPU6000::init()
 {
 	int ret;
+	int gyro_ret;
 
 	/* do SPI init (and probe) first */
 	ret = SPI::init();
@@ -371,6 +395,21 @@ MPU6000::init()
 		return ret;
 	}
 
+	/* allocate basic report buffers */
+	_num_accel_reports = 2;
+	_oldest_accel_report = _next_accel_report = 0;
+	_accel_reports = new struct accel_report[_num_accel_reports];
+
+	if (_accel_reports == nullptr)
+		goto out;
+
+	_num_gyro_reports = 2;
+	_oldest_gyro_report = _next_gyro_report = 0;
+	_gyro_reports = new struct gyro_report[_num_gyro_reports];
+
+	if (_gyro_reports == nullptr)
+		goto out;
+
 	// Chip reset
 	write_reg(MPUREG_PWR_MGMT_1, BIT_H_RESET);
 	up_udelay(10000);
@@ -462,7 +501,10 @@ MPU6000::init()
 	usleep(1000);
 
 	/* do CDev init for the gyro device node, keep it optional */
-	int gyro_ret = _gyro->init();
+	gyro_ret = _gyro->init();
+
+	memset(&_accel_reports[0], 0, sizeof(_accel_reports[0]));
+	memset(&_gyro_reports[0], 0, sizeof(_gyro_reports[0]));
 
 	/* ensure we got real values to share */
 	measure();
@@ -470,12 +512,13 @@ MPU6000::init()
 	if (gyro_ret != OK) {
 		_gyro_topic = -1;
 	} else {
-		_gyro_topic = orb_advertise(ORB_ID(sensor_gyro), &_gyro_report);
+		_gyro_topic = orb_advertise(ORB_ID(sensor_gyro), &_gyro_reports[0]);
 	}
 
-	/* advertise sensor topics */
-	_accel_topic = orb_advertise(ORB_ID(sensor_accel), &_accel_report);
+	/* advertise accel topic */
+	_accel_topic = orb_advertise(ORB_ID(sensor_accel), &_accel_reports[0]);
 
+out:
 	return ret;
 }
 
@@ -555,19 +598,40 @@ MPU6000::_set_dlpf_filter(uint16_t frequency_hz)
 ssize_t
 MPU6000::read(struct file *filp, char *buffer, size_t buflen)
 {
+	unsigned count = buflen / sizeof(struct accel_report);
 	int ret = 0;
 
 	/* buffer must be large enough */
-	if (buflen < sizeof(_accel_report))
+	if (count < 1)
 		return -ENOSPC;
 
-	/* if automatic measurement is not enabled */
-	if (_call_interval == 0)
-		measure();
+	/* if automatic measurement is enabled */
+	if (_call_interval > 0) {
 
-	/* copy out the latest reports */
-	memcpy(buffer, &_accel_report, sizeof(_accel_report));
-	ret = sizeof(_accel_report);
+		/*
+		 * While there is space in the caller's buffer, and reports, copy them.
+		 * Note that we may be pre-empted by the measurement code while we are doing this;
+		 * we are careful to avoid racing with it.
+		 */
+		while (count--) {
+			if (_oldest_accel_report != _next_accel_report) {
+				memcpy(buffer, _accel_reports + _oldest_accel_report, sizeof(*_accel_reports));
+				ret += sizeof(_accel_reports[0]);
+				INCREMENT(_oldest_accel_report, _num_accel_reports);
+			}
+		}
+
+		/* if there was no data, warn the caller */
+		return ret ? ret : -EAGAIN;
+	}
+
+	/* manual measurement */
+	_oldest_accel_report = _next_accel_report = 0;
+	measure();
+
+	/* measurement will have generated a report, copy it out */
+	memcpy(buffer, _accel_reports, sizeof(*_accel_reports));
+	ret = sizeof(*_accel_reports);
 
 	return ret;
 }
@@ -586,19 +650,40 @@ MPU6000::self_test()
 ssize_t
 MPU6000::gyro_read(struct file *filp, char *buffer, size_t buflen)
 {
+	unsigned count = buflen / sizeof(struct gyro_report);
 	int ret = 0;
 
 	/* buffer must be large enough */
-	if (buflen < sizeof(_gyro_report))
+	if (count < 1)
 		return -ENOSPC;
 
-	/* if automatic measurement is not enabled */
-	if (_call_interval == 0)
-		measure();
+	/* if automatic measurement is enabled */
+	if (_call_interval > 0) {
 
-	/* copy out the latest report */
-	memcpy(buffer, &_gyro_report, sizeof(_gyro_report));
-	ret = sizeof(_gyro_report);
+		/*
+		 * While there is space in the caller's buffer, and reports, copy them.
+		 * Note that we may be pre-empted by the measurement code while we are doing this;
+		 * we are careful to avoid racing with it.
+		 */
+		while (count--) {
+			if (_oldest_gyro_report != _next_gyro_report) {
+				memcpy(buffer, _gyro_reports + _oldest_gyro_report, sizeof(*_gyro_reports));
+				ret += sizeof(_gyro_reports[0]);
+				INCREMENT(_oldest_gyro_report, _num_gyro_reports);
+			}
+		}
+
+		/* if there was no data, warn the caller */
+		return ret ? ret : -EAGAIN;
+	}
+
+	/* manual measurement */
+	_oldest_gyro_report = _next_gyro_report = 0;
+	measure();
+
+	/* measurement will have generated a report, copy it out */
+	memcpy(buffer, _gyro_reports, sizeof(*_gyro_reports));
+	ret = sizeof(*_gyro_reports);
 
 	return ret;
 }
@@ -661,14 +746,32 @@ MPU6000::ioctl(struct file *filp, int cmd, unsigned long arg)
 
 		return 1000000 / _call_interval;
 
-	case SENSORIOCSQUEUEDEPTH:
-		/* XXX not implemented */
-		return -EINVAL;
+	case SENSORIOCSQUEUEDEPTH: {
+			/* account for sentinel in the ring */
+			arg++;
+
+			/* lower bound is mandatory, upper bound is a sanity check */
+			if ((arg < 2) || (arg > 100))
+				return -EINVAL;
+
+			/* allocate new buffer */
+			struct accel_report *buf = new struct accel_report[arg];
+
+			if (nullptr == buf)
+				return -ENOMEM;
+
+			/* reset the measurement state machine with the new buffer, free the old */
+			stop();
+			delete[] _accel_reports;
+			_num_accel_reports = arg;
+			_accel_reports = buf;
+			start();
+
+			return OK;
+		}
 
 	case SENSORIOCGQUEUEDEPTH:
-		/* XXX not implemented */
-		return -EINVAL;
-
+		return _num_accel_reports - 1;
 
 	case ACCELIOCGSAMPLERATE:
 		return _sample_rate;
@@ -726,11 +829,36 @@ MPU6000::gyro_ioctl(struct file *filp, int cmd, unsigned long arg)
 		/* these are shared with the accel side */
 	case SENSORIOCSPOLLRATE:
 	case SENSORIOCGPOLLRATE:
-	case SENSORIOCSQUEUEDEPTH:
-	case SENSORIOCGQUEUEDEPTH:
 	case SENSORIOCRESET:
 		return ioctl(filp, cmd, arg);
 
+	case SENSORIOCSQUEUEDEPTH: {
+			/* account for sentinel in the ring */
+			arg++;
+
+			/* lower bound is mandatory, upper bound is a sanity check */
+			if ((arg < 2) || (arg > 100))
+				return -EINVAL;
+
+			/* allocate new buffer */
+			struct gyro_report *buf = new struct gyro_report[arg];
+
+			if (nullptr == buf)
+				return -ENOMEM;
+
+			/* reset the measurement state machine with the new buffer, free the old */
+			stop();
+			delete[] _gyro_reports;
+			_num_gyro_reports = arg;
+			_gyro_reports = buf;
+			start();
+
+			return OK;
+		}
+
+	case SENSORIOCGQUEUEDEPTH:
+		return _num_gyro_reports - 1;
+
 	case GYROIOCGSAMPLERATE:
 		return _sample_rate;
 
@@ -959,10 +1087,16 @@ MPU6000::measure()
 	report.gyro_x = gyro_xt;
 	report.gyro_y = gyro_yt;
 
+	/*
+	 * Get references to the current reports
+	 */
+	accel_report		*accel_report = &_accel_reports[_next_accel_report];
+	gyro_report		*gyro_report = &_gyro_reports[_next_gyro_report];
+
 	/*
 	 * Adjust and scale results to m/s^2.
 	 */
-	_gyro_report.timestamp = _accel_report.timestamp = hrt_absolute_time();
+	gyro_report->timestamp = accel_report->timestamp = hrt_absolute_time();
 
 
 	/*
@@ -983,40 +1117,54 @@ MPU6000::measure()
 
 	/* NOTE: Axes have been swapped to match the board a few lines above. */
 
-	_accel_report.x_raw = report.accel_x;
-	_accel_report.y_raw = report.accel_y;
-	_accel_report.z_raw = report.accel_z;
+	accel_report->x_raw = report.accel_x;
+	accel_report->y_raw = report.accel_y;
+	accel_report->z_raw = report.accel_z;
 
-	_accel_report.x = ((report.accel_x * _accel_range_scale) - _accel_scale.x_offset) * _accel_scale.x_scale;
-	_accel_report.y = ((report.accel_y * _accel_range_scale) - _accel_scale.y_offset) * _accel_scale.y_scale;
-	_accel_report.z = ((report.accel_z * _accel_range_scale) - _accel_scale.z_offset) * _accel_scale.z_scale;
-	_accel_report.scaling = _accel_range_scale;
-	_accel_report.range_m_s2 = _accel_range_m_s2;
+	accel_report->x = ((report.accel_x * _accel_range_scale) - _accel_scale.x_offset) * _accel_scale.x_scale;
+	accel_report->y = ((report.accel_y * _accel_range_scale) - _accel_scale.y_offset) * _accel_scale.y_scale;
+	accel_report->z = ((report.accel_z * _accel_range_scale) - _accel_scale.z_offset) * _accel_scale.z_scale;
+	accel_report->scaling = _accel_range_scale;
+	accel_report->range_m_s2 = _accel_range_m_s2;
 
-	_accel_report.temperature_raw = report.temp;
-	_accel_report.temperature = (report.temp) / 361.0f + 35.0f;
+	accel_report->temperature_raw = report.temp;
+	accel_report->temperature = (report.temp) / 361.0f + 35.0f;
 
-	_gyro_report.x_raw = report.gyro_x;
-	_gyro_report.y_raw = report.gyro_y;
-	_gyro_report.z_raw = report.gyro_z;
+	gyro_report->x_raw = report.gyro_x;
+	gyro_report->y_raw = report.gyro_y;
+	gyro_report->z_raw = report.gyro_z;
 
-	_gyro_report.x = ((report.gyro_x * _gyro_range_scale) - _gyro_scale.x_offset) * _gyro_scale.x_scale;
-	_gyro_report.y = ((report.gyro_y * _gyro_range_scale) - _gyro_scale.y_offset) * _gyro_scale.y_scale;
-	_gyro_report.z = ((report.gyro_z * _gyro_range_scale) - _gyro_scale.z_offset) * _gyro_scale.z_scale;
-	_gyro_report.scaling = _gyro_range_scale;
-	_gyro_report.range_rad_s = _gyro_range_rad_s;
+	gyro_report->x = ((report.gyro_x * _gyro_range_scale) - _gyro_scale.x_offset) * _gyro_scale.x_scale;
+	gyro_report->y = ((report.gyro_y * _gyro_range_scale) - _gyro_scale.y_offset) * _gyro_scale.y_scale;
+	gyro_report->z = ((report.gyro_z * _gyro_range_scale) - _gyro_scale.z_offset) * _gyro_scale.z_scale;
+	gyro_report->scaling = _gyro_range_scale;
+	gyro_report->range_rad_s = _gyro_range_rad_s;
 
-	_gyro_report.temperature_raw = report.temp;
-	_gyro_report.temperature = (report.temp) / 361.0f + 35.0f;
+	gyro_report->temperature_raw = report.temp;
+	gyro_report->temperature = (report.temp) / 361.0f + 35.0f;
+
+	/* ACCEL: post a report to the ring - note, not locked */
+	INCREMENT(_next_accel_report, _num_accel_reports);
+
+	/* ACCEL: if we are running up against the oldest report, fix it */
+	if (_next_accel_report == _oldest_accel_report)
+		INCREMENT(_oldest_accel_report, _num_accel_reports);
+
+	/* GYRO: post a report to the ring - note, not locked */
+	INCREMENT(_next_gyro_report, _num_gyro_reports);
+
+	/* GYRO: if we are running up against the oldest report, fix it */
+	if (_next_gyro_report == _oldest_gyro_report)
+		INCREMENT(_oldest_gyro_report, _num_gyro_reports);
 
 	/* notify anyone waiting for data */
 	poll_notify(POLLIN);
 	_gyro->parent_poll_notify();
 
 	/* and publish for subscribers */
-	orb_publish(ORB_ID(sensor_accel), _accel_topic, &_accel_report);
+	orb_publish(ORB_ID(sensor_accel), _accel_topic, accel_report);
 	if (_gyro_topic != -1) {
-		orb_publish(ORB_ID(sensor_gyro), _gyro_topic, &_gyro_report);
+		orb_publish(ORB_ID(sensor_gyro), _gyro_topic, gyro_report);
 	}
 
 	/* stop measuring */

From a3ab88872cbca30be62b04461c8294399923ec89 Mon Sep 17 00:00:00 2001
From: px4dev <px4@purgatory.org>
Date: Sat, 3 Aug 2013 19:02:54 -0700
Subject: [PATCH 02/11] Add some more useful methods to the ringbuffer class.

---
 src/drivers/device/ringbuffer.h | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/src/drivers/device/ringbuffer.h b/src/drivers/device/ringbuffer.h
index 37686fdbe3..dc0c84052b 100644
--- a/src/drivers/device/ringbuffer.h
+++ b/src/drivers/device/ringbuffer.h
@@ -104,6 +104,17 @@ public:
 	 */
 	bool			full() { return _next(_head) == _tail; }
 
+	/*
+	 * Returns the capacity of the buffer, or zero if the buffer could
+	 * not be allocated.
+	 */
+	unsigned		size() { return (_buf != nullptr) ? _size : 0; }
+
+	/*
+	 * Empties the buffer.
+	 */
+	void			flush() { _head = _tail = _size; }
+
 private:
 	T			*const _buf;	
 	const unsigned		_size;
@@ -114,11 +125,11 @@ private:
 };
 
 template <typename T>
-RingBuffer<T>::RingBuffer(unsigned size) :
-	_buf(new T[size + 1]),
-	_size(size),
- 	_head(size),
- 	_tail(size)
+RingBuffer<T>::RingBuffer(unsigned with_size) :
+	_buf(new T[with_size + 1]),
+	_size(with_size),
+ 	_head(with_size),
+ 	_tail(with_size)
 {}
 
 template <typename T>

From 02f5b79948742d6b7121399e39444286cc01f161 Mon Sep 17 00:00:00 2001
From: px4dev <px4@purgatory.org>
Date: Sat, 3 Aug 2013 19:03:24 -0700
Subject: [PATCH 03/11] Try to save our sanity a bit and use the generic
 ringbuffer class rather than re-implementing the wheel.

---
 src/drivers/mpu6000/mpu6000.cpp | 255 +++++++++++++-------------------
 1 file changed, 104 insertions(+), 151 deletions(-)

diff --git a/src/drivers/mpu6000/mpu6000.cpp b/src/drivers/mpu6000/mpu6000.cpp
index d37d39a7ab..f848cca6b8 100644
--- a/src/drivers/mpu6000/mpu6000.cpp
+++ b/src/drivers/mpu6000/mpu6000.cpp
@@ -67,6 +67,7 @@
 #include <drivers/drv_hrt.h>
 
 #include <drivers/device/spi.h>
+#include <drivers/device/ringbuffer.h>
 #include <drivers/drv_accel.h>
 #include <drivers/drv_gyro.h>
 
@@ -181,20 +182,16 @@ private:
 	struct hrt_call		_call;
 	unsigned		_call_interval;
 
-	unsigned		_num_accel_reports;
-	volatile unsigned	_next_accel_report;
-	volatile unsigned	_oldest_accel_report;
-	struct accel_report	*_accel_reports;
+	typedef RingBuffer<accel_report> AccelReportBuffer;
+	AccelReportBuffer	*_accel_reports;
 
 	struct accel_scale	_accel_scale;
 	float			_accel_range_scale;
 	float			_accel_range_m_s2;
 	orb_advert_t		_accel_topic;
 
-	unsigned		_num_gyro_reports;
-	volatile unsigned	_next_gyro_report;
-	volatile unsigned	_oldest_gyro_report;
-	struct gyro_report	*_gyro_reports;
+	typedef RingBuffer<gyro_report> GyroReportBuffer;
+	GyroReportBuffer	*_gyro_reports;
 
 	struct gyro_scale	_gyro_scale;
 	float			_gyro_range_scale;
@@ -227,7 +224,7 @@ private:
 	static void		measure_trampoline(void *arg);
 
 	/**
-	 * Fetch measurements from the sensor and update the report ring.
+	 * Fetch measurements from the sensor and update the report buffers.
 	 */
 	void			measure();
 
@@ -314,24 +311,15 @@ private:
 /** driver 'main' command */
 extern "C" { __EXPORT int mpu6000_main(int argc, char *argv[]); }
 
-/* helper macro for handling report buffer indices */
-#define INCREMENT(_x, _lim)	do { _x++; if (_x >= _lim) _x = 0; } while(0)
-
 MPU6000::MPU6000(int bus, spi_dev_e device) :
 	SPI("MPU6000", ACCEL_DEVICE_PATH, bus, device, SPIDEV_MODE3, 10000000),
 	_gyro(new MPU6000_gyro(this)),
 	_product(0),
 	_call_interval(0),
-	_num_accel_reports(0),
-	_next_accel_report(0),
-	_oldest_accel_report(0),
 	_accel_reports(nullptr),
 	_accel_range_scale(0.0f),
 	_accel_range_m_s2(0.0f),
 	_accel_topic(-1),
-	_num_gyro_reports(0),
-	_next_gyro_report(0),
-	_oldest_gyro_report(0),
 	_gyro_reports(nullptr),
 	_gyro_range_scale(0.0f),
 	_gyro_range_rad_s(0.0f),
@@ -372,9 +360,9 @@ MPU6000::~MPU6000()
 
 	/* free any existing reports */
 	if (_accel_reports != nullptr)
-		delete[] _accel_reports;
+		delete _accel_reports;
 	if (_gyro_reports != nullptr)
-		delete[] _gyro_reports;
+		delete _gyro_reports;
 
 	/* delete the perf counter */
 	perf_free(_sample_perf);
@@ -396,17 +384,11 @@ MPU6000::init()
 	}
 
 	/* allocate basic report buffers */
-	_num_accel_reports = 2;
-	_oldest_accel_report = _next_accel_report = 0;
-	_accel_reports = new struct accel_report[_num_accel_reports];
-
+	_accel_reports = new AccelReportBuffer(2);
 	if (_accel_reports == nullptr)
 		goto out;
 
-	_num_gyro_reports = 2;
-	_oldest_gyro_report = _next_gyro_report = 0;
-	_gyro_reports = new struct gyro_report[_num_gyro_reports];
-
+	_gyro_reports = new GyroReportBuffer(2);
 	if (_gyro_reports == nullptr)
 		goto out;
 
@@ -503,20 +485,22 @@ MPU6000::init()
 	/* do CDev init for the gyro device node, keep it optional */
 	gyro_ret = _gyro->init();
 
-	memset(&_accel_reports[0], 0, sizeof(_accel_reports[0]));
-	memset(&_gyro_reports[0], 0, sizeof(_gyro_reports[0]));
-
-	/* ensure we got real values to share */
+	/* fetch an initial set of measurements for advertisement */
 	measure();
 
 	if (gyro_ret != OK) {
 		_gyro_topic = -1;
 	} else {
-		_gyro_topic = orb_advertise(ORB_ID(sensor_gyro), &_gyro_reports[0]);
+		gyro_report gr;
+		_gyro_reports->get(gr);
+
+		_gyro_topic = orb_advertise(ORB_ID(sensor_gyro), &gr);
 	}
 
 	/* advertise accel topic */
-	_accel_topic = orb_advertise(ORB_ID(sensor_accel), &_accel_reports[0]);
+	accel_report ar;
+	_accel_reports->get(ar);
+	_accel_topic = orb_advertise(ORB_ID(sensor_accel), &ar);
 
 out:
 	return ret;
@@ -598,42 +582,31 @@ MPU6000::_set_dlpf_filter(uint16_t frequency_hz)
 ssize_t
 MPU6000::read(struct file *filp, char *buffer, size_t buflen)
 {
-	unsigned count = buflen / sizeof(struct accel_report);
-	int ret = 0;
+	unsigned count = buflen / sizeof(accel_report);
 
 	/* buffer must be large enough */
 	if (count < 1)
 		return -ENOSPC;
 
-	/* if automatic measurement is enabled */
-	if (_call_interval > 0) {
-
-		/*
-		 * While there is space in the caller's buffer, and reports, copy them.
-		 * Note that we may be pre-empted by the measurement code while we are doing this;
-		 * we are careful to avoid racing with it.
-		 */
-		while (count--) {
-			if (_oldest_accel_report != _next_accel_report) {
-				memcpy(buffer, _accel_reports + _oldest_accel_report, sizeof(*_accel_reports));
-				ret += sizeof(_accel_reports[0]);
-				INCREMENT(_oldest_accel_report, _num_accel_reports);
-			}
-		}
-
-		/* if there was no data, warn the caller */
-		return ret ? ret : -EAGAIN;
+	/* if automatic measurement is not enabled, get a fresh measurement into the buffer */
+	if (_call_interval == 0) {
+		_accel_reports->flush();
+		measure();
 	}
 
-	/* manual measurement */
-	_oldest_accel_report = _next_accel_report = 0;
-	measure();
+	/* if no data, error (we could block here) */
+	if (_accel_reports->empty())
+		return -EAGAIN;
 
-	/* measurement will have generated a report, copy it out */
-	memcpy(buffer, _accel_reports, sizeof(*_accel_reports));
-	ret = sizeof(*_accel_reports);
+	/* copy reports out of our buffer to the caller */
+	accel_report *arp = reinterpret_cast<accel_report *>(buffer);
+	while (count--) {
+		if (!_accel_reports->get(*arp++))
+			break;
+	}
 
-	return ret;
+	/* return the number of bytes transferred */
+	return (buflen - (count * sizeof(accel_report)));
 }
 
 int
@@ -651,41 +624,30 @@ ssize_t
 MPU6000::gyro_read(struct file *filp, char *buffer, size_t buflen)
 {
 	unsigned count = buflen / sizeof(struct gyro_report);
-	int ret = 0;
 
 	/* buffer must be large enough */
 	if (count < 1)
 		return -ENOSPC;
 
-	/* if automatic measurement is enabled */
-	if (_call_interval > 0) {
-
-		/*
-		 * While there is space in the caller's buffer, and reports, copy them.
-		 * Note that we may be pre-empted by the measurement code while we are doing this;
-		 * we are careful to avoid racing with it.
-		 */
-		while (count--) {
-			if (_oldest_gyro_report != _next_gyro_report) {
-				memcpy(buffer, _gyro_reports + _oldest_gyro_report, sizeof(*_gyro_reports));
-				ret += sizeof(_gyro_reports[0]);
-				INCREMENT(_oldest_gyro_report, _num_gyro_reports);
-			}
-		}
-
-		/* if there was no data, warn the caller */
-		return ret ? ret : -EAGAIN;
+	/* if automatic measurement is not enabled, get a fresh measurement into the buffer */
+	if (_call_interval == 0) {
+		_gyro_reports->flush();
+		measure();
 	}
 
-	/* manual measurement */
-	_oldest_gyro_report = _next_gyro_report = 0;
-	measure();
+	/* if no data, error (we could block here) */
+	if (_gyro_reports->empty())
+		return -EAGAIN;
 
-	/* measurement will have generated a report, copy it out */
-	memcpy(buffer, _gyro_reports, sizeof(*_gyro_reports));
-	ret = sizeof(*_gyro_reports);
+	/* copy reports out of our buffer to the caller */
+	gyro_report *arp = reinterpret_cast<gyro_report *>(buffer);
+	while (count--) {
+		if (!_gyro_reports->get(*arp++))
+			break;
+	}
 
-	return ret;
+	/* return the number of bytes transferred */
+	return (buflen - (count * sizeof(gyro_report)));
 }
 
 int
@@ -747,23 +709,23 @@ MPU6000::ioctl(struct file *filp, int cmd, unsigned long arg)
 		return 1000000 / _call_interval;
 
 	case SENSORIOCSQUEUEDEPTH: {
-			/* account for sentinel in the ring */
-			arg++;
-
 			/* lower bound is mandatory, upper bound is a sanity check */
-			if ((arg < 2) || (arg > 100))
+			if ((arg < 1) || (arg > 100))
 				return -EINVAL;
 
 			/* allocate new buffer */
-			struct accel_report *buf = new struct accel_report[arg];
+			AccelReportBuffer *buf = new AccelReportBuffer(arg);
 
 			if (nullptr == buf)
 				return -ENOMEM;
+			if (buf->size() == 0) {
+				delete buf;
+				return -ENOMEM;
+			}
 
 			/* reset the measurement state machine with the new buffer, free the old */
 			stop();
-			delete[] _accel_reports;
-			_num_accel_reports = arg;
+			delete _accel_reports;
 			_accel_reports = buf;
 			start();
 
@@ -771,14 +733,14 @@ MPU6000::ioctl(struct file *filp, int cmd, unsigned long arg)
 		}
 
 	case SENSORIOCGQUEUEDEPTH:
-		return _num_accel_reports - 1;
+		return _accel_reports->size();
 
 	case ACCELIOCGSAMPLERATE:
 		return _sample_rate;
 
 	case ACCELIOCSSAMPLERATE:
-	  _set_sample_rate(arg);
-	  return OK;
+		_set_sample_rate(arg);
+		return OK;
 
 	case ACCELIOCSLOWPASS:
 	case ACCELIOCGLOWPASS:
@@ -833,23 +795,23 @@ MPU6000::gyro_ioctl(struct file *filp, int cmd, unsigned long arg)
 		return ioctl(filp, cmd, arg);
 
 	case SENSORIOCSQUEUEDEPTH: {
-			/* account for sentinel in the ring */
-			arg++;
-
 			/* lower bound is mandatory, upper bound is a sanity check */
-			if ((arg < 2) || (arg > 100))
+			if ((arg < 1) || (arg > 100))
 				return -EINVAL;
 
 			/* allocate new buffer */
-			struct gyro_report *buf = new struct gyro_report[arg];
+			GyroReportBuffer *buf = new GyroReportBuffer(arg);
 
 			if (nullptr == buf)
 				return -ENOMEM;
+			if (buf->size() == 0) {
+				delete buf;
+				return -ENOMEM;
+			}
 
 			/* reset the measurement state machine with the new buffer, free the old */
 			stop();
-			delete[] _gyro_reports;
-			_num_gyro_reports = arg;
+			delete _gyro_reports;
 			_gyro_reports = buf;
 			start();
 
@@ -857,7 +819,7 @@ MPU6000::gyro_ioctl(struct file *filp, int cmd, unsigned long arg)
 		}
 
 	case SENSORIOCGQUEUEDEPTH:
-		return _num_gyro_reports - 1;
+		return _gyro_reports->size();
 
 	case GYROIOCGSAMPLERATE:
 		return _sample_rate;
@@ -993,6 +955,10 @@ MPU6000::start()
 	/* make sure we are stopped first */
 	stop();
 
+	/* discard any stale data in the buffers */
+	_accel_reports->flush();
+	_gyro_reports->flush();
+
 	/* start polling at the specified rate */
 	hrt_call_every(&_call, 1000, _call_interval, (hrt_callout)&MPU6000::measure_trampoline, this);
 }
@@ -1006,7 +972,7 @@ MPU6000::stop()
 void
 MPU6000::measure_trampoline(void *arg)
 {
-	MPU6000 *dev = (MPU6000 *)arg;
+	MPU6000 *dev = reinterpret_cast<MPU6000 *>(arg);
 
 	/* make another measurement */
 	dev->measure();
@@ -1088,15 +1054,15 @@ MPU6000::measure()
 	report.gyro_y = gyro_yt;
 
 	/*
-	 * Get references to the current reports
+	 * Report buffers.
 	 */
-	accel_report		*accel_report = &_accel_reports[_next_accel_report];
-	gyro_report		*gyro_report = &_gyro_reports[_next_gyro_report];
+	accel_report		arb;
+	gyro_report		grb;
 
 	/*
 	 * Adjust and scale results to m/s^2.
 	 */
-	gyro_report->timestamp = accel_report->timestamp = hrt_absolute_time();
+	grb.timestamp = arb.timestamp = hrt_absolute_time();
 
 
 	/*
@@ -1117,54 +1083,43 @@ MPU6000::measure()
 
 	/* NOTE: Axes have been swapped to match the board a few lines above. */
 
-	accel_report->x_raw = report.accel_x;
-	accel_report->y_raw = report.accel_y;
-	accel_report->z_raw = report.accel_z;
+	arb.x_raw = report.accel_x;
+	arb.y_raw = report.accel_y;
+	arb.z_raw = report.accel_z;
 
-	accel_report->x = ((report.accel_x * _accel_range_scale) - _accel_scale.x_offset) * _accel_scale.x_scale;
-	accel_report->y = ((report.accel_y * _accel_range_scale) - _accel_scale.y_offset) * _accel_scale.y_scale;
-	accel_report->z = ((report.accel_z * _accel_range_scale) - _accel_scale.z_offset) * _accel_scale.z_scale;
-	accel_report->scaling = _accel_range_scale;
-	accel_report->range_m_s2 = _accel_range_m_s2;
+	arb.x = ((report.accel_x * _accel_range_scale) - _accel_scale.x_offset) * _accel_scale.x_scale;
+	arb.y = ((report.accel_y * _accel_range_scale) - _accel_scale.y_offset) * _accel_scale.y_scale;
+	arb.z = ((report.accel_z * _accel_range_scale) - _accel_scale.z_offset) * _accel_scale.z_scale;
+	arb.scaling = _accel_range_scale;
+	arb.range_m_s2 = _accel_range_m_s2;
 
-	accel_report->temperature_raw = report.temp;
-	accel_report->temperature = (report.temp) / 361.0f + 35.0f;
+	arb.temperature_raw = report.temp;
+	arb.temperature = (report.temp) / 361.0f + 35.0f;
 
-	gyro_report->x_raw = report.gyro_x;
-	gyro_report->y_raw = report.gyro_y;
-	gyro_report->z_raw = report.gyro_z;
+	grb.x_raw = report.gyro_x;
+	grb.y_raw = report.gyro_y;
+	grb.z_raw = report.gyro_z;
 
-	gyro_report->x = ((report.gyro_x * _gyro_range_scale) - _gyro_scale.x_offset) * _gyro_scale.x_scale;
-	gyro_report->y = ((report.gyro_y * _gyro_range_scale) - _gyro_scale.y_offset) * _gyro_scale.y_scale;
-	gyro_report->z = ((report.gyro_z * _gyro_range_scale) - _gyro_scale.z_offset) * _gyro_scale.z_scale;
-	gyro_report->scaling = _gyro_range_scale;
-	gyro_report->range_rad_s = _gyro_range_rad_s;
+	grb.x = ((report.gyro_x * _gyro_range_scale) - _gyro_scale.x_offset) * _gyro_scale.x_scale;
+	grb.y = ((report.gyro_y * _gyro_range_scale) - _gyro_scale.y_offset) * _gyro_scale.y_scale;
+	grb.z = ((report.gyro_z * _gyro_range_scale) - _gyro_scale.z_offset) * _gyro_scale.z_scale;
+	grb.scaling = _gyro_range_scale;
+	grb.range_rad_s = _gyro_range_rad_s;
 
-	gyro_report->temperature_raw = report.temp;
-	gyro_report->temperature = (report.temp) / 361.0f + 35.0f;
+	grb.temperature_raw = report.temp;
+	grb.temperature = (report.temp) / 361.0f + 35.0f;
 
-	/* ACCEL: post a report to the ring - note, not locked */
-	INCREMENT(_next_accel_report, _num_accel_reports);
-
-	/* ACCEL: if we are running up against the oldest report, fix it */
-	if (_next_accel_report == _oldest_accel_report)
-		INCREMENT(_oldest_accel_report, _num_accel_reports);
-
-	/* GYRO: post a report to the ring - note, not locked */
-	INCREMENT(_next_gyro_report, _num_gyro_reports);
-
-	/* GYRO: if we are running up against the oldest report, fix it */
-	if (_next_gyro_report == _oldest_gyro_report)
-		INCREMENT(_oldest_gyro_report, _num_gyro_reports);
+	_accel_reports->put(arb);
+	_gyro_reports->put(grb);
 
 	/* notify anyone waiting for data */
 	poll_notify(POLLIN);
 	_gyro->parent_poll_notify();
 
 	/* and publish for subscribers */
-	orb_publish(ORB_ID(sensor_accel), _accel_topic, accel_report);
+	orb_publish(ORB_ID(sensor_accel), _accel_topic, &arb);
 	if (_gyro_topic != -1) {
-		orb_publish(ORB_ID(sensor_gyro), _gyro_topic, gyro_report);
+		orb_publish(ORB_ID(sensor_gyro), _gyro_topic, &grb);
 	}
 
 	/* stop measuring */
@@ -1267,21 +1222,19 @@ fail:
 void
 test()
 {
-	int fd = -1;
-	int fd_gyro = -1;
-	struct accel_report a_report;
-	struct gyro_report g_report;
+	accel_report a_report;
+	gyro_report g_report;
 	ssize_t sz;
 
 	/* get the driver */
-	fd = open(ACCEL_DEVICE_PATH, O_RDONLY);
+	int fd = open(ACCEL_DEVICE_PATH, O_RDONLY);
 
 	if (fd < 0)
 		err(1, "%s open failed (try 'mpu6000 start' if the driver is not running)",
 		    ACCEL_DEVICE_PATH);
 
 	/* get the driver */
-	fd_gyro = open(GYRO_DEVICE_PATH, O_RDONLY);
+	int fd_gyro = open(GYRO_DEVICE_PATH, O_RDONLY);
 
 	if (fd_gyro < 0)
 		err(1, "%s open failed", GYRO_DEVICE_PATH);

From f45e74265e3952f350970d665adccdf539e136f2 Mon Sep 17 00:00:00 2001
From: Lorenz Meier <lm@inf.ethz.ch>
Date: Sun, 4 Aug 2013 15:15:41 +0200
Subject: [PATCH 04/11] Fixed driver test / direct read, looks good

---
 src/drivers/mpu6000/mpu6000.cpp | 111 ++++++++++++++++++++------------
 1 file changed, 70 insertions(+), 41 deletions(-)

diff --git a/src/drivers/mpu6000/mpu6000.cpp b/src/drivers/mpu6000/mpu6000.cpp
index f848cca6b8..9dcb4be9ed 100644
--- a/src/drivers/mpu6000/mpu6000.cpp
+++ b/src/drivers/mpu6000/mpu6000.cpp
@@ -212,6 +212,13 @@ private:
 	 */
 	void			stop();
 
+	/**
+	 * Reset chip.
+	 *
+	 * Resets the chip and measurements ranges, but not scale and offset.
+	 */
+	void			reset();
+
 	/**
 	 * Static trampoline from the hrt_call context; because we don't have a
 	 * generic hrt wrapper yet.
@@ -392,6 +399,50 @@ MPU6000::init()
 	if (_gyro_reports == nullptr)
 		goto out;
 
+	reset();
+
+	/* Initialize offsets and scales */
+	_accel_scale.x_offset = 0;
+	_accel_scale.x_scale  = 1.0f;
+	_accel_scale.y_offset = 0;
+	_accel_scale.y_scale  = 1.0f;
+	_accel_scale.z_offset = 0;
+	_accel_scale.z_scale  = 1.0f;
+
+	_gyro_scale.x_offset = 0;
+	_gyro_scale.x_scale  = 1.0f;
+	_gyro_scale.y_offset = 0;
+	_gyro_scale.y_scale  = 1.0f;
+	_gyro_scale.z_offset = 0;
+	_gyro_scale.z_scale  = 1.0f;
+
+	/* do CDev init for the gyro device node, keep it optional */
+	gyro_ret = _gyro->init();
+
+	/* fetch an initial set of measurements for advertisement */
+	measure();
+
+	if (gyro_ret != OK) {
+		_gyro_topic = -1;
+	} else {
+		gyro_report gr;
+		_gyro_reports->get(gr);
+
+		_gyro_topic = orb_advertise(ORB_ID(sensor_gyro), &gr);
+	}
+
+	/* advertise accel topic */
+	accel_report ar;
+	_accel_reports->get(ar);
+	_accel_topic = orb_advertise(ORB_ID(sensor_accel), &ar);
+
+out:
+	return ret;
+}
+
+void MPU6000::reset()
+{
+
 	// Chip reset
 	write_reg(MPUREG_PWR_MGMT_1, BIT_H_RESET);
 	up_udelay(10000);
@@ -423,12 +474,6 @@ MPU6000::init()
 	// 2000 deg/s = (2000/180)*PI = 34.906585 rad/s
 	// scaling factor:
 	// 1/(2^15)*(2000/180)*PI
-	_gyro_scale.x_offset = 0;
-	_gyro_scale.x_scale  = 1.0f;
-	_gyro_scale.y_offset = 0;
-	_gyro_scale.y_scale  = 1.0f;
-	_gyro_scale.z_offset = 0;
-	_gyro_scale.z_scale  = 1.0f;
 	_gyro_range_scale = (0.0174532 / 16.4);//1.0f / (32768.0f * (2000.0f / 180.0f) * M_PI_F);
 	_gyro_range_rad_s = (2000.0f / 180.0f) * M_PI_F;
 
@@ -461,12 +506,6 @@ MPU6000::init()
 
 	// Correct accel scale factors of 4096 LSB/g
 	// scale to m/s^2 ( 1g = 9.81 m/s^2)
-	_accel_scale.x_offset = 0;
-	_accel_scale.x_scale  = 1.0f;
-	_accel_scale.y_offset = 0;
-	_accel_scale.y_scale  = 1.0f;
-	_accel_scale.z_offset = 0;
-	_accel_scale.z_scale  = 1.0f;
 	_accel_range_scale = (9.81f / 4096.0f);
 	_accel_range_m_s2 = 8.0f * 9.81f;
 
@@ -482,28 +521,6 @@ MPU6000::init()
 	// write_reg(MPUREG_PWR_MGMT_1,MPU_CLK_SEL_PLLGYROZ);
 	usleep(1000);
 
-	/* do CDev init for the gyro device node, keep it optional */
-	gyro_ret = _gyro->init();
-
-	/* fetch an initial set of measurements for advertisement */
-	measure();
-
-	if (gyro_ret != OK) {
-		_gyro_topic = -1;
-	} else {
-		gyro_report gr;
-		_gyro_reports->get(gr);
-
-		_gyro_topic = orb_advertise(ORB_ID(sensor_gyro), &gr);
-	}
-
-	/* advertise accel topic */
-	accel_report ar;
-	_accel_reports->get(ar);
-	_accel_topic = orb_advertise(ORB_ID(sensor_accel), &ar);
-
-out:
-	return ret;
 }
 
 int
@@ -600,13 +617,15 @@ MPU6000::read(struct file *filp, char *buffer, size_t buflen)
 
 	/* copy reports out of our buffer to the caller */
 	accel_report *arp = reinterpret_cast<accel_report *>(buffer);
+	int transferred = 0;
 	while (count--) {
 		if (!_accel_reports->get(*arp++))
 			break;
+		transferred++;
 	}
 
 	/* return the number of bytes transferred */
-	return (buflen - (count * sizeof(accel_report)));
+	return (transferred * sizeof(accel_report));
 }
 
 int
@@ -623,7 +642,7 @@ MPU6000::self_test()
 ssize_t
 MPU6000::gyro_read(struct file *filp, char *buffer, size_t buflen)
 {
-	unsigned count = buflen / sizeof(struct gyro_report);
+	unsigned count = buflen / sizeof(gyro_report);
 
 	/* buffer must be large enough */
 	if (count < 1)
@@ -641,13 +660,15 @@ MPU6000::gyro_read(struct file *filp, char *buffer, size_t buflen)
 
 	/* copy reports out of our buffer to the caller */
 	gyro_report *arp = reinterpret_cast<gyro_report *>(buffer);
+	int transferred = 0;
 	while (count--) {
 		if (!_gyro_reports->get(*arp++))
 			break;
+		transferred++;
 	}
 
 	/* return the number of bytes transferred */
-	return (buflen - (count * sizeof(gyro_report)));
+	return (transferred * sizeof(gyro_report));
 }
 
 int
@@ -655,6 +676,10 @@ MPU6000::ioctl(struct file *filp, int cmd, unsigned long arg)
 {
 	switch (cmd) {
 
+	case SENSORIOCRESET:
+		reset();
+		return OK;
+
 	case SENSORIOCSPOLLRATE: {
 			switch (arg) {
 
@@ -674,8 +699,8 @@ MPU6000::ioctl(struct file *filp, int cmd, unsigned long arg)
 				/* set default/max polling rate */
 			case SENSOR_POLLRATE_MAX:
 			case SENSOR_POLLRATE_DEFAULT:
-				/* XXX 500Hz is just a wild guess */
-				return ioctl(filp, SENSORIOCSPOLLRATE, 500);
+				/* set to same as sample rate per default */
+				return ioctl(filp, SENSORIOCSPOLLRATE, _sample_rate);
 
 				/* adjust to a legal polling interval in Hz */
 			default: {
@@ -1246,8 +1271,10 @@ test()
 	/* do a simple demand read */
 	sz = read(fd, &a_report, sizeof(a_report));
 
-	if (sz != sizeof(a_report))
+	if (sz != sizeof(a_report)) {
+		warnx("ret: %d, expected: %d", sz, sizeof(a_report));
 		err(1, "immediate acc read failed");
+	}
 
 	warnx("single read");
 	warnx("time:     %lld", a_report.timestamp);
@@ -1263,8 +1290,10 @@ test()
 	/* do a simple demand read */
 	sz = read(fd_gyro, &g_report, sizeof(g_report));
 
-	if (sz != sizeof(g_report))
+	if (sz != sizeof(g_report)) {
+		warnx("ret: %d, expected: %d", sz, sizeof(g_report));
 		err(1, "immediate gyro read failed");
+	}
 
 	warnx("gyro x: \t% 9.5f\trad/s", (double)g_report.x);
 	warnx("gyro y: \t% 9.5f\trad/s", (double)g_report.y);

From 36cca7a31b428408eb686df592f092ba5fc24006 Mon Sep 17 00:00:00 2001
From: Lorenz Meier <lm@inf.ethz.ch>
Date: Sun, 4 Aug 2013 19:10:56 +0200
Subject: [PATCH 05/11] Added rate limit in sensors app. Just pending accel
 filters now

---
 src/modules/sensors/sensors.cpp | 66 +++++++++++++++++++++++++++++++--
 1 file changed, 63 insertions(+), 3 deletions(-)

diff --git a/src/modules/sensors/sensors.cpp b/src/modules/sensors/sensors.cpp
index 7ff9e19b4c..0f1782fca6 100644
--- a/src/modules/sensors/sensors.cpp
+++ b/src/modules/sensors/sensors.cpp
@@ -92,8 +92,35 @@
 #define BARO_HEALTH_COUNTER_LIMIT_OK 5
 #define ADC_HEALTH_COUNTER_LIMIT_OK  5
 
-#define ADC_BATTERY_VOLTAGE_CHANNEL	10
-#define ADC_AIRSPEED_VOLTAGE_CHANNEL	11
+/**
+ * Analog layout:
+ * FMU:
+ * IN2 - battery voltage
+ * IN3 - battery current
+ * IN4 - 5V sense
+ * IN10 - spare (we could actually trim these from the set)
+ * IN11 - spare (we could actually trim these from the set)
+ * IN12 - spare (we could actually trim these from the set)
+ * IN13 - aux1
+ * IN14 - aux2
+ * IN15 - pressure sensor
+ * 
+ * IO:
+ * IN4 - servo supply rail
+ * IN5 - analog RSSI
+ */
+
+#ifdef CONFIG_ARCH_BOARD_PX4FMU_V1
+  #define ADC_BATTERY_VOLTAGE_CHANNEL	10
+  #define ADC_AIRSPEED_VOLTAGE_CHANNEL	11
+#endif
+
+#ifdef CONFIG_ARCH_BOARD_PX4FMU_V2
+  #define ADC_BATTERY_VOLTAGE_CHANNEL	2
+  #define ADC_BATTERY_CURRENT_CHANNEL	3
+  #define ADC_5V_RAIL_SENSE		4
+  #define ADC_AIRSPEED_VOLTAGE_CHANNEL	15
+#endif
 
 #define BAT_VOL_INITIAL 0.f
 #define BAT_VOL_LOWPASS_1 0.99f
@@ -731,12 +758,27 @@ Sensors::accel_init()
 		errx(1, "FATAL: no accelerometer found");
 
 	} else {
+
+		// XXX do the check more elegantly
+
+		#ifdef CONFIG_ARCH_BOARD_PX4FMU_V1
+
 		/* set the accel internal sampling rate up to at leat 500Hz */
 		ioctl(fd, ACCELIOCSSAMPLERATE, 500);
 
 		/* set the driver to poll at 500Hz */
 		ioctl(fd, SENSORIOCSPOLLRATE, 500);
 
+		#else
+
+		/* set the accel internal sampling rate up to at leat 800Hz */
+		ioctl(fd, ACCELIOCSSAMPLERATE, 800);
+
+		/* set the driver to poll at 800Hz */
+		ioctl(fd, SENSORIOCSPOLLRATE, 800);
+
+		#endif
+
 		warnx("using system accel");
 		close(fd);
 	}
@@ -754,12 +796,27 @@ Sensors::gyro_init()
 		errx(1, "FATAL: no gyro found");
 
 	} else {
+
+		// XXX do the check more elegantly
+
+		#ifdef CONFIG_ARCH_BOARD_PX4FMU_V1
+
 		/* set the gyro internal sampling rate up to at leat 500Hz */
 		ioctl(fd, GYROIOCSSAMPLERATE, 500);
 
 		/* set the driver to poll at 500Hz */
 		ioctl(fd, SENSORIOCSPOLLRATE, 500);
 
+		#else
+
+		/* set the gyro internal sampling rate up to at leat 800Hz */
+		ioctl(fd, GYROIOCSSAMPLERATE, 800);
+
+		/* set the driver to poll at 800Hz */
+		ioctl(fd, SENSORIOCSPOLLRATE, 800);
+
+		#endif
+
 		warnx("using system gyro");
 		close(fd);
 	}
@@ -1360,6 +1417,9 @@ Sensors::task_main()
 	/* rate limit vehicle status updates to 5Hz */
 	orb_set_interval(_vstatus_sub, 200);
 
+	/* rate limit gyro to 250 Hz (the gyro signal is lowpassed accordingly earlier) */
+	orb_set_interval(_gyro_sub, 4);
+
 	/*
 	 * do advertisements
 	 */
@@ -1395,7 +1455,7 @@ Sensors::task_main()
 
 	while (!_task_should_exit) {
 
-		/* wait for up to 500ms for data */
+		/* wait for up to 100ms for data */
 		int pret = poll(&fds[0], (sizeof(fds) / sizeof(fds[0])), 100);
 
 		/* timed out - periodic check for _task_should_exit, etc. */

From ac89322d74ac1f5a29a6665feb4220aba3025f82 Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <tridge@samba.org>
Date: Sun, 4 Aug 2013 15:09:16 +1000
Subject: [PATCH 06/11] mathlib: added LowPassFilter2p object

used in gyro and accel drivers for better filtering
---
 .../mathlib/math/filter/LowPassFilter2p.cpp   | 77 ++++++++++++++++++
 .../mathlib/math/filter/LowPassFilter2p.hpp   | 78 +++++++++++++++++++
 src/modules/mathlib/math/filter/module.mk     | 44 +++++++++++
 3 files changed, 199 insertions(+)
 create mode 100644 src/modules/mathlib/math/filter/LowPassFilter2p.cpp
 create mode 100644 src/modules/mathlib/math/filter/LowPassFilter2p.hpp
 create mode 100644 src/modules/mathlib/math/filter/module.mk

diff --git a/src/modules/mathlib/math/filter/LowPassFilter2p.cpp b/src/modules/mathlib/math/filter/LowPassFilter2p.cpp
new file mode 100644
index 0000000000..efb17225d2
--- /dev/null
+++ b/src/modules/mathlib/math/filter/LowPassFilter2p.cpp
@@ -0,0 +1,77 @@
+// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
+
+/****************************************************************************
+ *
+ *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/// @file	LowPassFilter.cpp
+/// @brief	A class to implement a second order low pass filter 
+/// Author: Leonard Hall <LeonardTHall@gmail.com>
+
+#include "LowPassFilter2p.hpp"
+#include "math.h"
+
+namespace math
+{
+
+void LowPassFilter2p::set_cutoff_frequency(float sample_freq, float cutoff_freq)
+{
+    _cutoff_freq = cutoff_freq;
+    float fr = sample_freq/_cutoff_freq;
+    float ohm = tanf(M_PI_F/fr);
+    float c = 1.0f+2.0f*cosf(M_PI_F/4.0f)*ohm + ohm*ohm;
+    _b0 = ohm*ohm/c;
+    _b1 = 2.0f*_b0;
+    _b2 = _b0;
+    _a1 = 2.0f*(ohm*ohm-1.0f)/c;
+    _a2 = (1.0f-2.0f*cosf(M_PI_F/4.0f)*ohm+ohm*ohm)/c;
+}
+
+float LowPassFilter2p::apply(float sample)
+{
+    // do the filtering
+    float delay_element_0 = sample - _delay_element_1 * _a1 - _delay_element_2 * _a2;
+    if (isnan(delay_element_0) || isinf(delay_element_0)) {
+        // don't allow bad values to propogate via the filter
+        delay_element_0 = sample;
+    }
+    float output = delay_element_0 * _b0 + _delay_element_1 * _b1 + _delay_element_2 * _b2;
+    
+    _delay_element_2 = _delay_element_1;
+    _delay_element_1 = delay_element_0;
+
+    // return the value.  Should be no need to check limits
+    return output;
+}
+
+} // namespace math
+
diff --git a/src/modules/mathlib/math/filter/LowPassFilter2p.hpp b/src/modules/mathlib/math/filter/LowPassFilter2p.hpp
new file mode 100644
index 0000000000..208ec98d4e
--- /dev/null
+++ b/src/modules/mathlib/math/filter/LowPassFilter2p.hpp
@@ -0,0 +1,78 @@
+// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
+
+/****************************************************************************
+ *
+ *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/// @file	LowPassFilter.h
+/// @brief	A class to implement a second order low pass filter 
+/// Author: Leonard Hall <LeonardTHall@gmail.com>
+/// Adapted for PX4 by Andrew Tridgell
+
+#pragma once
+
+namespace math
+{
+class __EXPORT LowPassFilter2p
+{
+public:
+    // constructor
+    LowPassFilter2p(float sample_freq, float cutoff_freq) {
+        // set initial parameters
+        set_cutoff_frequency(sample_freq, cutoff_freq);
+        _delay_element_1 = _delay_element_2 = 0;
+    }
+
+    // change parameters
+    void set_cutoff_frequency(float sample_freq, float cutoff_freq);
+
+    // apply - Add a new raw value to the filter 
+    // and retrieve the filtered result
+    float apply(float sample);
+
+    // return the cutoff frequency
+    float get_cutoff_freq(void) const {
+        return _cutoff_freq;
+    }
+
+private:
+    float           _cutoff_freq; 
+    float           _a1;
+    float           _a2;
+    float           _b0;
+    float           _b1;
+    float           _b2;
+    float           _delay_element_1;        // buffered sample -1
+    float           _delay_element_2;        // buffered sample -2
+};
+
+} // namespace math
diff --git a/src/modules/mathlib/math/filter/module.mk b/src/modules/mathlib/math/filter/module.mk
new file mode 100644
index 0000000000..fe92c8c70f
--- /dev/null
+++ b/src/modules/mathlib/math/filter/module.mk
@@ -0,0 +1,44 @@
+############################################################################
+#
+#   Copyright (c) 2012, 2013 PX4 Development Team. All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in
+#    the documentation and/or other materials provided with the
+#    distribution.
+# 3. Neither the name PX4 nor the names of its contributors may be
+#    used to endorse or promote products derived from this software
+#    without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+############################################################################
+
+#
+# filter library
+#
+SRCS		 = LowPassFilter2p.cpp
+
+#
+# In order to include .config we first have to save off the
+# current makefile name, since app.mk needs it.
+#
+APP_MAKEFILE	:= $(lastword $(MAKEFILE_LIST))
+-include $(TOPDIR)/.config

From 7c3ee6714c0e184c297ffced880488a41e7d255d Mon Sep 17 00:00:00 2001
From: Lorenz Meier <lm@inf.ethz.ch>
Date: Sun, 4 Aug 2013 19:14:25 +0200
Subject: [PATCH 07/11] Enabled mathlib

---
 makefiles/config_px4fmu-v1_default.mk | 1 +
 1 file changed, 1 insertion(+)

diff --git a/makefiles/config_px4fmu-v1_default.mk b/makefiles/config_px4fmu-v1_default.mk
index e6ec840f9a..38cf437e03 100644
--- a/makefiles/config_px4fmu-v1_default.mk
+++ b/makefiles/config_px4fmu-v1_default.mk
@@ -94,6 +94,7 @@ MODULES		+= modules/sdlog2
 MODULES		+= modules/systemlib
 MODULES		+= modules/systemlib/mixer
 MODULES		+= modules/mathlib
+MODULES		+= modules/mathlib/math/filter
 MODULES		+= modules/controllib
 MODULES		+= modules/uORB
 

From b5d19d08ea02bd31e27f4259302b30946e1f673d Mon Sep 17 00:00:00 2001
From: Lorenz Meier <lm@inf.ethz.ch>
Date: Mon, 5 Aug 2013 21:05:08 +0200
Subject: [PATCH 08/11] Equipped MPU6k driver with Butterworth for accel and
 gyro

---
 src/drivers/mpu6000/mpu6000.cpp | 74 +++++++++++++++++++++++++++------
 1 file changed, 62 insertions(+), 12 deletions(-)

diff --git a/src/drivers/mpu6000/mpu6000.cpp b/src/drivers/mpu6000/mpu6000.cpp
index 9dcb4be9ed..be0a040284 100644
--- a/src/drivers/mpu6000/mpu6000.cpp
+++ b/src/drivers/mpu6000/mpu6000.cpp
@@ -70,6 +70,7 @@
 #include <drivers/device/ringbuffer.h>
 #include <drivers/drv_accel.h>
 #include <drivers/drv_gyro.h>
+#include <mathlib/math/filter/LowPassFilter2p.hpp>
 
 #define DIR_READ			0x80
 #define DIR_WRITE			0x00
@@ -202,6 +203,13 @@ private:
 	unsigned		_sample_rate;
 	perf_counter_t		_sample_perf;
 
+	math::LowPassFilter2p	_accel_filter_x;
+	math::LowPassFilter2p	_accel_filter_y;
+	math::LowPassFilter2p	_accel_filter_z;
+	math::LowPassFilter2p	_gyro_filter_x;
+	math::LowPassFilter2p	_gyro_filter_y;
+	math::LowPassFilter2p	_gyro_filter_z;
+
 	/**
 	 * Start automatic measurement.
 	 */
@@ -332,8 +340,14 @@ MPU6000::MPU6000(int bus, spi_dev_e device) :
 	_gyro_range_rad_s(0.0f),
 	_gyro_topic(-1),
 	_reads(0),
-	_sample_rate(500),
-	_sample_perf(perf_alloc(PC_ELAPSED, "mpu6000_read"))
+	_sample_rate(1000),
+	_sample_perf(perf_alloc(PC_ELAPSED, "mpu6000_read")),
+	_accel_filter_x(1000, 30),
+	_accel_filter_y(1000, 30),
+	_accel_filter_z(1000, 30),
+	_gyro_filter_x(1000, 30),
+        _gyro_filter_y(1000, 30),
+        _gyro_filter_z(1000, 30)
 {
 	// disable debug() calls
 	_debug_enabled = false;
@@ -714,6 +728,19 @@ MPU6000::ioctl(struct file *filp, int cmd, unsigned long arg)
 					if (ticks < 1000)
 						return -EINVAL;
 
+					// adjust filters
+					float cutoff_freq_hz = _accel_filter_x.get_cutoff_freq();
+					float sample_rate = 1.0e6f/ticks;
+					_accel_filter_x.set_cutoff_frequency(sample_rate, cutoff_freq_hz);
+					_accel_filter_y.set_cutoff_frequency(sample_rate, cutoff_freq_hz);
+					_accel_filter_z.set_cutoff_frequency(sample_rate, cutoff_freq_hz);
+
+
+					float cutoff_freq_hz_gyro = _gyro_filter_x.get_cutoff_freq();
+					_gyro_filter_x.set_cutoff_frequency(sample_rate, cutoff_freq_hz_gyro);
+					_gyro_filter_y.set_cutoff_frequency(sample_rate, cutoff_freq_hz_gyro);
+					_gyro_filter_z.set_cutoff_frequency(sample_rate, cutoff_freq_hz_gyro);
+
 					/* update interval for next measurement */
 					/* XXX this is a bit shady, but no other way to adjust... */
 					_call.period = _call_interval = ticks;
@@ -767,9 +794,17 @@ MPU6000::ioctl(struct file *filp, int cmd, unsigned long arg)
 		_set_sample_rate(arg);
 		return OK;
 
-	case ACCELIOCSLOWPASS:
 	case ACCELIOCGLOWPASS:
-		_set_dlpf_filter((uint16_t)arg);
+		return _accel_filter_x.get_cutoff_freq();
+
+	case ACCELIOCSLOWPASS:
+		
+		// XXX decide on relationship of both filters
+		// i.e. disable the on-chip filter
+		//_set_dlpf_filter((uint16_t)arg);
+                _accel_filter_x.set_cutoff_frequency(1.0e6f / _call_interval, arg);
+                _accel_filter_y.set_cutoff_frequency(1.0e6f / _call_interval, arg);
+                _accel_filter_z.set_cutoff_frequency(1.0e6f / _call_interval, arg);
 		return OK;
 
 	case ACCELIOCSSCALE:
@@ -853,9 +888,14 @@ MPU6000::gyro_ioctl(struct file *filp, int cmd, unsigned long arg)
 		_set_sample_rate(arg);
 		return OK;
 
-	case GYROIOCSLOWPASS:
 	case GYROIOCGLOWPASS:
-		_set_dlpf_filter((uint16_t)arg);
+		return _gyro_filter_x.get_cutoff_freq();
+	case GYROIOCSLOWPASS:
+		_gyro_filter_x.set_cutoff_frequency(1.0e6f / _call_interval, arg);
+		_gyro_filter_y.set_cutoff_frequency(1.0e6f / _call_interval, arg);
+		_gyro_filter_z.set_cutoff_frequency(1.0e6f / _call_interval, arg);
+		// XXX check relation to the internal lowpass
+		//_set_dlpf_filter((uint16_t)arg);
 		return OK;
 
 	case GYROIOCSSCALE:
@@ -1112,9 +1152,14 @@ MPU6000::measure()
 	arb.y_raw = report.accel_y;
 	arb.z_raw = report.accel_z;
 
-	arb.x = ((report.accel_x * _accel_range_scale) - _accel_scale.x_offset) * _accel_scale.x_scale;
-	arb.y = ((report.accel_y * _accel_range_scale) - _accel_scale.y_offset) * _accel_scale.y_scale;
-	arb.z = ((report.accel_z * _accel_range_scale) - _accel_scale.z_offset) * _accel_scale.z_scale;
+	float x_in_new = ((report.accel_x * _accel_range_scale) - _accel_scale.x_offset) * _accel_scale.x_scale;
+	float y_in_new = ((report.accel_y * _accel_range_scale) - _accel_scale.y_offset) * _accel_scale.y_scale;
+	float z_in_new = ((report.accel_z * _accel_range_scale) - _accel_scale.z_offset) * _accel_scale.z_scale;
+	
+	arb.x = _accel_filter_x.apply(x_in_new);
+	arb.y = _accel_filter_y.apply(y_in_new);
+	arb.z = _accel_filter_z.apply(z_in_new);
+
 	arb.scaling = _accel_range_scale;
 	arb.range_m_s2 = _accel_range_m_s2;
 
@@ -1125,9 +1170,14 @@ MPU6000::measure()
 	grb.y_raw = report.gyro_y;
 	grb.z_raw = report.gyro_z;
 
-	grb.x = ((report.gyro_x * _gyro_range_scale) - _gyro_scale.x_offset) * _gyro_scale.x_scale;
-	grb.y = ((report.gyro_y * _gyro_range_scale) - _gyro_scale.y_offset) * _gyro_scale.y_scale;
-	grb.z = ((report.gyro_z * _gyro_range_scale) - _gyro_scale.z_offset) * _gyro_scale.z_scale;
+	float x_gyro_in_new = ((report.gyro_x * _gyro_range_scale) - _gyro_scale.x_offset) * _gyro_scale.x_scale;
+	float y_gyro_in_new = ((report.gyro_y * _gyro_range_scale) - _gyro_scale.y_offset) * _gyro_scale.y_scale;
+	float z_gyro_in_new = ((report.gyro_z * _gyro_range_scale) - _gyro_scale.z_offset) * _gyro_scale.z_scale;
+	
+	grb.x = _gyro_filter_x.apply(x_gyro_in_new);
+	grb.y = _gyro_filter_y.apply(y_gyro_in_new);
+	grb.z = _gyro_filter_z.apply(z_gyro_in_new);
+
 	grb.scaling = _gyro_range_scale;
 	grb.range_rad_s = _gyro_range_rad_s;
 

From a2f923b9a3bf403e3a9fcee39d87c7aecc28559d Mon Sep 17 00:00:00 2001
From: Lorenz Meier <lm@inf.ethz.ch>
Date: Mon, 5 Aug 2013 21:05:34 +0200
Subject: [PATCH 09/11] Increased MPU6K poll and sampling rate to 1 KHz

---
 src/modules/sensors/sensors.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/modules/sensors/sensors.cpp b/src/modules/sensors/sensors.cpp
index 0f1782fca6..5dc23f5c13 100644
--- a/src/modules/sensors/sensors.cpp
+++ b/src/modules/sensors/sensors.cpp
@@ -763,11 +763,11 @@ Sensors::accel_init()
 
 		#ifdef CONFIG_ARCH_BOARD_PX4FMU_V1
 
-		/* set the accel internal sampling rate up to at leat 500Hz */
-		ioctl(fd, ACCELIOCSSAMPLERATE, 500);
+		/* set the accel internal sampling rate up to at leat 1000Hz */
+		ioctl(fd, ACCELIOCSSAMPLERATE, 1000);
 
-		/* set the driver to poll at 500Hz */
-		ioctl(fd, SENSORIOCSPOLLRATE, 500);
+		/* set the driver to poll at 1000Hz */
+		ioctl(fd, SENSORIOCSPOLLRATE, 1000);
 
 		#else
 

From cfd737aa734f9b0cd97f79148d6b959978b2cad0 Mon Sep 17 00:00:00 2001
From: Lorenz Meier <lm@inf.ethz.ch>
Date: Mon, 5 Aug 2013 21:08:19 +0200
Subject: [PATCH 10/11] Made sensors startup routine more flexible

---
 src/modules/sensors/sensors.cpp | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/modules/sensors/sensors.cpp b/src/modules/sensors/sensors.cpp
index 5dc23f5c13..f7b41b1207 100644
--- a/src/modules/sensors/sensors.cpp
+++ b/src/modules/sensors/sensors.cpp
@@ -801,11 +801,13 @@ Sensors::gyro_init()
 
 		#ifdef CONFIG_ARCH_BOARD_PX4FMU_V1
 
-		/* set the gyro internal sampling rate up to at leat 500Hz */
-		ioctl(fd, GYROIOCSSAMPLERATE, 500);
+		/* set the gyro internal sampling rate up to at least 1000Hz */
+		if (ioctl(fd, GYROIOCSSAMPLERATE, 1000) != OK)
+			ioctl(fd, GYROIOCSSAMPLERATE, 800);
 
-		/* set the driver to poll at 500Hz */
-		ioctl(fd, SENSORIOCSPOLLRATE, 500);
+		/* set the driver to poll at 1000Hz */
+		if (ioctl(fd, SENSORIOCSPOLLRATE, 1000) != OK)
+			ioctl(fd, SENSORIOCSPOLLRATE, 800);
 
 		#else
 

From 338e506a28e4233bc8a16493530f3b82a0dd67e9 Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <tridge@samba.org>
Date: Tue, 6 Aug 2013 16:33:01 +1000
Subject: [PATCH 11/11] mpu6000: set the default DLFP filter to 42Hz

this allows for apps to ask for slightly higher filters with the
software filter and not have it completely ruined by the on-chip DLPF
---
 src/drivers/mpu6000/mpu6000.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/drivers/mpu6000/mpu6000.cpp b/src/drivers/mpu6000/mpu6000.cpp
index be0a040284..c4e331a30e 100644
--- a/src/drivers/mpu6000/mpu6000.cpp
+++ b/src/drivers/mpu6000/mpu6000.cpp
@@ -477,7 +477,7 @@ void MPU6000::reset()
 	// FS & DLPF   FS=2000 deg/s, DLPF = 20Hz (low pass filter)
 	// was 90 Hz, but this ruins quality and does not improve the
 	// system response
-	_set_dlpf_filter(20);
+	_set_dlpf_filter(42);
 	usleep(1000);
 	// Gyro scale 2000 deg/s ()
 	write_reg(MPUREG_GYRO_CONFIG, BITS_FS_2000DPS);