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mpu6000: change bus speed based on registers being accessed 

this ensures we follow the datasheet requirement of 1MHz for general
registers and up to 20MHz for sensor and int status registers
This commit is contained in:
Andrew Tridgell 2013-10-30 09:46:52 +11:00 committed by Lorenz Meier
parent 8df4d636ab
commit 97af3d2204
1 changed files with 22 additions and 1 deletions
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23
src/drivers/mpu6000/mpu6000.cpp
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@ -161,6 +161,14 @@
#define MPU6000_ONE_G 9.80665f
/*
the MPU6000 can only handle high SPI bus speeds on the sensor and
interrupt status registers. All other registers have a maximum 1MHz
SPI speed
*/
#define MPU6000_LOW_BUS_SPEED 1000*1000
#define MPU6000_HIGH_BUS_SPEED 10*1000*1000
class MPU6000_gyro;
class MPU6000 : public device::SPI
@ -351,7 +359,7 @@ private:
extern "C" { __EXPORT int mpu6000_main(int argc, char *argv[]); }
MPU6000::MPU6000(int bus, spi_dev_e device) :
SPI("MPU6000", ACCEL_DEVICE_PATH, bus, device, SPIDEV_MODE3, 10000000),
SPI("MPU6000", ACCEL_DEVICE_PATH, bus, device, SPIDEV_MODE3, MPU6000_LOW_BUS_SPEED),
_gyro(new MPU6000_gyro(this)),
_product(0),
_call_interval(0),
@ -991,6 +999,9 @@ MPU6000::read_reg(unsigned reg)
cmd[0] = reg | DIR_READ;
// general register transfer at low clock speed
set_frequency(MPU6000_LOW_BUS_SPEED);
transfer(cmd, cmd, sizeof(cmd));
return cmd[1];
@ -1003,6 +1014,9 @@ MPU6000::read_reg16(unsigned reg)
cmd[0] = reg | DIR_READ;
// general register transfer at low clock speed
set_frequency(MPU6000_LOW_BUS_SPEED);
transfer(cmd, cmd, sizeof(cmd));
return (uint16_t)(cmd[1] << 8) | cmd[2];
@ -1016,6 +1030,9 @@ MPU6000::write_reg(unsigned reg, uint8_t value)
cmd[0] = reg | DIR_WRITE;
cmd[1] = value;
// general register transfer at low clock speed
set_frequency(MPU6000_LOW_BUS_SPEED);
transfer(cmd, nullptr, sizeof(cmd));
}
@ -1139,6 +1156,10 @@ MPU6000::measure()
* Fetch the full set of measurements from the MPU6000 in one pass.
*/
mpu_report.cmd = DIR_READ | MPUREG_INT_STATUS;
// sensor transfer at high clock speed
set_frequency(MPU6000_HIGH_BUS_SPEED);
if (OK != transfer((uint8_t *)&mpu_report, ((uint8_t *)&mpu_report), sizeof(mpu_report)))
return;