AP_HAL_Linux: add ADC support for PXF cape

libraries/AP_HAL_Linux/AP_HAL_Linux_Private.h

@@ -14,6 +14,7 @@
 #include "AnalogIn.h"
 #include "AnalogIn_ADS1115.h"
 #include "RaspilotAnalogIn.h"
+#include "AnalogIn_PXF.h"
 #include "Storage.h"
 #include "GPIO.h"
 #include "RCInput.h"

libraries/AP_HAL_Linux/AnalogIn_PXF.cpp

@@ -0,0 +1,142 @@
+/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
+#include <AP_HAL/AP_HAL.h>
+
+#if CONFIG_HAL_BOARD == HAL_BOARD_LINUX
+#include "AnalogIn_PXF.h"
+
+extern const AP_HAL::HAL& hal;
+
+
+
+const char* PXFAnalogSource::analog_sources[PXF_ANALOG_IN_COUNT] = {
+    "in_voltage0_raw",
+    "in_voltage1_raw",
+    "in_voltage2_raw",
+    "in_voltage3_raw",
+    "in_voltage4_raw",
+    "in_voltage5_raw",
+    "in_voltage6_raw",            
+    "in_voltage7_raw",                        
+};
+
+PXFAnalogSource::PXFAnalogSource(int16_t pin, float initial_value) :
+    _pin(pin),
+    _value(initial_value),
+    _sum_value(0),
+    _sum_count(0),
+    _pin_fd(-1)
+{
+    reopen_pin();
+}
+
+void PXFAnalogSource::reopen_pin(void)
+{
+    char buf[100];
+
+    if (_pin_fd != -1) {
+        close(_pin_fd);
+        _pin_fd = -1;
+    }
+
+    if (_pin < 0) {
+        return;
+    }
+    
+    if (_pin > PXF_ANALOG_IN_COUNT) {
+        // invalid pin
+        return;
+    }
+
+    // Construct the path by appending strings
+    strncpy(buf, PXF_ANALOG_IN_DIR, sizeof(buf));
+    strncat(buf, PXFAnalogSource::analog_sources[_pin], sizeof(buf));
+    
+    _pin_fd = open(buf, O_RDONLY | O_NONBLOCK);
+    if (_pin_fd == -1) {
+        ::printf("Failed to open analog pin %s\n", buf);
+    }    
+}
+
+float PXFAnalogSource::read_average() 
+{
+    read_latest();
+    if (_sum_count == 0) {
+        return _value;
+    }
+    hal.scheduler->suspend_timer_procs();
+    _value = _sum_value / _sum_count;
+    // _value_ratiometric = _sum_ratiometric / _sum_count;
+    _sum_value = 0;
+    // _sum_ratiometric = 0;
+    _sum_count = 0;
+    hal.scheduler->resume_timer_procs();
+    return _value;
+}
+
+float PXFAnalogSource::read_latest() 
+{
+    char sbuf[10];
+
+    if (_pin_fd == -1) {
+        _latest = 0;
+        return 0;
+    }
+
+    memset(sbuf, 0, sizeof(sbuf));
+    pread(_pin_fd, sbuf, sizeof(sbuf)-1, 0);
+
+    _latest = atoi(sbuf) * BBB_VOLTAGE_SCALING;      
+    _sum_value += _latest;
+    _sum_count++;
+
+    return _latest;
+}
+
+// output is in volts
+float PXFAnalogSource::voltage_average() 
+{
+    return read_average();
+}
+
+float PXFAnalogSource::voltage_latest() 
+{
+    read_latest();
+    return _latest;
+}
+
+void PXFAnalogSource::set_pin(uint8_t pin)
+{
+    if (_pin == pin) {
+        return;
+    }
+
+    hal.scheduler->suspend_timer_procs();
+    _pin = pin;
+    _sum_value = 0;
+    // _sum_ratiometric = 0;
+    _sum_count = 0;
+    _latest = 0;
+    _value = 0;    
+    reopen_pin();
+    // _value_ratiometric = 0;
+    hal.scheduler->resume_timer_procs();
+}
+
+void PXFAnalogSource::set_stop_pin(uint8_t p)
+{}
+
+void PXFAnalogSource::set_settle_time(uint16_t settle_time_ms)
+{}
+
+PXFAnalogIn::PXFAnalogIn()
+{}
+
+void PXFAnalogIn::init(void* machtnichts)
+{}
+
+
+AP_HAL::AnalogSource* PXFAnalogIn::channel(int16_t pin) {
+    return new PXFAnalogSource(pin, 0);
+}
+
+#endif // CONFIG_HAL_BOARD

libraries/AP_HAL_Linux/AnalogIn_PXF.h

@@ -0,0 +1,55 @@
+
+#ifndef __AP_HAL_PXF_ANALOGIN_H__
+#define __AP_HAL_PXF_ANALOGIN_H__
+
+#include "AP_HAL_Linux.h"
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+
+#define PXF_ANALOG_IN_COUNT 8
+// Note that echo BB-ADC cape should be loaded
+#define PXF_ANALOG_IN_DIR "/sys/bus/iio/devices/iio:device0/"
+#define BBB_VOLTAGE_SCALING 0.00142602816
+
+class PXFAnalogSource : public AP_HAL::AnalogSource {
+public:
+    friend class PXFAnalogIn;
+    PXFAnalogSource(int16_t pin, float v);
+    float read_average();
+    float read_latest();
+    void set_pin(uint8_t p);
+    void set_stop_pin(uint8_t p);
+    void set_settle_time(uint16_t settle_time_ms);
+    float voltage_average();
+    float voltage_latest();
+    float voltage_average_ratiometric() { return voltage_average(); }
+private:
+    float       _value;
+    float       _latest;
+    float       _sum_value;
+    // float       _value_ratiometric;
+    uint8_t     _sum_count;
+    int16_t     _pin;
+    int         _pin_fd;    
+
+    void reopen_pin(void);
+
+    static const char *analog_sources[PXF_ANALOG_IN_COUNT];
+};
+
+class PXFAnalogIn : public AP_HAL::AnalogIn {
+public:
+    PXFAnalogIn();
+    void init(void* implspecific);
+    AP_HAL::AnalogSource* channel(int16_t n);
+
+    // we don't yet know how to get the board voltage
+    float board_voltage(void) { return 0.0f; }
+
+};
+#endif // __AP_HAL_PXF_ANALOGIN_H__

libraries/AP_HAL_Linux/HAL_Linux_Class.cpp

@@ -82,6 +82,8 @@ static ADS1115AnalogIn analogIn;
 static RaspilotAnalogIn analogIn;
 #elif CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_QFLIGHT
 static Empty::AnalogIn analogIn;
+#elif CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_PXF || CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_ERLE
+static PXFAnalogIn analogIn;
 #else
 static AnalogIn analogIn;
 #endif