Improve voltage measurement

Apply PWM_VOLT_PIN without reboot.
Check if the voltage pin can be used with ADC when setting up.
Set voltage to NAN, when it's unknown (including pyflix).
pyflix@0.15.
Don't send BATTERY_STATUS when voltage is unknown.
Add dummy voltage to the simulator.

flix/mavlink.ino

@@ -46,7 +46,7 @@ void sendMavlink() {
 		float remaining = constrain(mapf(voltage, 3.4, 4.2, 0, 1), 0, 1);
 		mavlink_msg_battery_status_pack(mavlinkSysId, MAV_COMP_ID_AUTOPILOT1, &msg, 0, MAV_BATTERY_FUNCTION_ALL,
 			MAV_BATTERY_TYPE_LIPO, INT16_MAX, voltages, -1, -1, -1, remaining * 100, 0, MAV_BATTERY_CHARGE_STATE_OK, voltagesExt, 0, 0);
-		sendMessage(&msg);
+		if (valid(voltage)) sendMessage(&msg);
 	}
 
 	if (telemetryFast && mavlinkConnected) {

flix/parameters.ino

@@ -117,7 +117,7 @@ Parameter parameters[] = {
 	{"MAV_RATE_SLOW", &telemetrySlow.rate},
 	{"MAV_RATE_FAST", &telemetryFast.rate},
 	// power
-	{"PWR_VOLT_PIN", &voltagePin},
+	{"PWR_VOLT_PIN", &voltagePin, setupPower},
 	{"PWR_VOLT_SCALE", &voltageScale},
 	{"PWR_VOLT_LPF_A", &voltageFilter.alpha},
 	// safety

flix/power.ino

@@ -8,14 +8,14 @@
 #include "lpf.h"
 #include "util.h"
 
-float voltage;
+float voltage = NAN;
 LowPassFilter<float> voltageFilter(0.2);
 int voltagePin = -1;
 float voltageScale = 2;
 
 void setupPower() {
-	// Disable reset on low voltage
-	REG_CLR_BIT(RTC_CNTL_BROWN_OUT_REG, RTC_CNTL_BROWN_OUT_ENA);
+	REG_CLR_BIT(RTC_CNTL_BROWN_OUT_REG, RTC_CNTL_BROWN_OUT_ENA); // disable reset on low voltage
+	if (digitalPinToAnalogChannel(voltagePin) == -1) voltagePin = -1; // test ADC pin
 }
 
 void readVoltage() {

gazebo/Arduino.h

@@ -168,6 +168,7 @@ void delay(uint32_t ms) {
 bool ledcAttach(uint8_t pin, uint32_t freq, uint8_t resolution) { return true; }
 bool ledcWrite(uint8_t pin, uint32_t duty) { return true; }
 uint32_t ledcChangeFrequency(uint8_t pin, uint32_t freq, uint8_t resolution) { return freq; }
+int8_t digitalPinToAnalogChannel(uint8_t pin) { return -1; }
 uint32_t analogReadMilliVolts(uint8_t pin) { return 0; }
 
 unsigned long __micros;

gazebo/flix.h

@@ -58,6 +58,7 @@ void handleMavlink(const void *_msg);
 void mavlinkPrint(const char* str);
 void sendMavlinkPrint();
 inline Quaternion fluToFrd(const Quaternion &q);
+void setupPower();
 void failsafe();
 void rcLossFailsafe();
 void descend();

gazebo/simulator.cpp

@@ -73,6 +73,8 @@ public:
 		gyro = Vector(imu->AngularVelocity().X(), imu->AngularVelocity().Y(), imu->AngularVelocity().Z());
 		acc = this->accFilter.update(Vector(imu->LinearAcceleration().X(), imu->LinearAcceleration().Y(), imu->LinearAcceleration().Z()));
 
+		voltage = 4.2f; // dummy voltage value
+
 		readRC();
 		estimate();
 

tools/pyflix/README.md

@@ -37,7 +37,7 @@ print(flix.connected)       # True if connected to the drone
 print(flix.mode)            # current flight mode (str)
 print(flix.armed)           # True if the drone is armed
 print(flix.landed)          # True if the drone is landed
-print(flix.voltage)         # battery voltage
+print(flix.voltage)         # battery voltage (NaN - unknown, ~0 - USB powered)
 print(flix.attitude)        # attitude quaternion [w, x, y, z]
 print(flix.attitude_euler)  # attitude as Euler angles [roll, pitch, yaw]
 print(flix.rates)           # angular rates [roll_rate, pitch_rate, yaw_rate]

tools/pyflix/flix.py

@@ -5,6 +5,7 @@
 
 import os
 import time
+import math
 from queue import Queue, Empty
 from typing import Optional, Callable, List, Dict, Any, Union, Sequence
 import logging
@@ -26,7 +27,7 @@ class Flix:
     mode: str = ''
     armed: bool = False
     landed: bool = False
-    voltage: float = 0
+    voltage: float = math.nan
     attitude: List[float]
     attitude_euler: List[float]  # roll, pitch, yaw
     rates: List[float]

tools/pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "pyflix"
-version = "0.14"
+version = "0.15"
 description = "Python API for Flix drone"
 authors = [{ name="Oleg Kalachev", email="okalachev@gmail.com" }]
 license = "MIT"