Use double for storing time instead of float

Float precision may be not enough after some time of operating

docs/firmware.md

@@ -6,7 +6,7 @@
 
 The main loop is running at 1000 Hz. All the dataflow is happening through global variables (for simplicity):
 
-* `t` *(float)* — current step time, *s*.
+* `t` *(double)* — current step time, *s*.
 * `dt` *(float)* — time delta between the current and previous steps, *s*.
 * `gyro` *(Vector)* — data from the gyroscope, *rad/s*.
 * `acc` *(Vector)* — acceleration data from the accelerometer, *m/s<sup>2</sup>*.

flix/cli.ino

@@ -8,7 +8,7 @@
 
 extern const int MOTOR_REAR_LEFT, MOTOR_REAR_RIGHT, MOTOR_FRONT_RIGHT, MOTOR_FRONT_LEFT;
 extern float loopRate, dt;
-extern float t;
+extern double t;
 extern int rollChannel, pitchChannel, throttleChannel, yawChannel, armedChannel, modeChannel;
 
 const char* motd =

flix/failsafe.ino

@@ -6,7 +6,7 @@
 #define RC_LOSS_TIMEOUT 0.2
 #define DESCEND_TIME 3.0 // time to descend from full throttle to zero
 
-extern float controlsTime;
+extern double controlsTime;
 extern int rollChannel, pitchChannel, throttleChannel, yawChannel;
 
 void failsafe() {

flix/flix.ino

@@ -10,7 +10,7 @@
 #define SERIAL_BAUDRATE 115200
 #define WIFI_ENABLED 1
 
-float t = NAN; // current step time, s
+double t = NAN; // current step time, s
 float dt; // time delta from previous step, s
 int16_t channels[16]; // raw rc channels
 float controls[16]; // normalized controls in range [-1..1] ([0..1] for throttle)

flix/log.ino

@@ -10,6 +10,7 @@
 #define LOG_PERIOD 1.0 / LOG_RATE
 #define LOG_SIZE LOG_DURATION * LOG_RATE
 
+float tFloat;
 Vector attitudeEuler;
 Vector attitudeTargetEuler;
 
@@ -19,7 +20,7 @@ struct LogEntry {
 };
 
 LogEntry logEntries[] = {
-	{"t", &t},
+	{"t", &tFloat},
 	{"rates.x", &rates.x},
 	{"rates.y", &rates.y},
 	{"rates.z", &rates.z},
@@ -39,6 +40,7 @@ const int logColumns = sizeof(logEntries) / sizeof(logEntries[0]);
 float logBuffer[LOG_SIZE][logColumns];
 
 void prepareLogData() {
+	tFloat = t;
 	attitudeEuler = attitude.toEulerZYX();
 	attitudeTargetEuler = attitudeTarget.toEulerZYX();
 }
@@ -46,7 +48,7 @@ void prepareLogData() {
 void logData() {
 	if (!armed) return;
 	static int logPointer = 0;
-	static float logTime = 0;
+	static double logTime = 0;
 	if (t - logTime < LOG_PERIOD) return;
 	logTime = t;
 

flix/mavlink.ino

@@ -13,7 +13,7 @@
 #define MAVLINK_CONTROL_SCALE 0.7f
 #define MAVLINK_CONTROL_YAW_DEAD_ZONE 0.1f
 
-extern float controlsTime;
+extern double controlsTime;
 extern int rollChannel, pitchChannel, throttleChannel, yawChannel, armedChannel, modeChannel;
 
 void processMavlink() {
@@ -22,8 +22,8 @@ void processMavlink() {
 }
 
 void sendMavlink() {
-	static float lastSlow = 0;
-	static float lastFast = 0;
+	static double lastSlow = 0;
+	static double lastFast = 0;
 
 	mavlink_message_t msg;
 	uint32_t time = t * 1000;

flix/parameters.ino

@@ -113,7 +113,7 @@ bool setParameter(const char *name, const float value) {
 }
 
 void syncParameters() {
-	static float lastSync = 0;
+	static double lastSync = 0;
 	if (t - lastSync < 1) return; // sync once per second
 	if (motorsActive()) return; // don't use flash while flying, it may cause a delay
 	lastSync = t;

flix/rc.ino

@@ -14,7 +14,7 @@ int yawChannel = 3;
 int armedChannel = 4;
 int modeChannel = 5;
 
-float controlsTime; // time of the last controls update
+double controlsTime; // time of the last controls update
 float channelNeutral[16] = {NAN}; // first element NAN means not calibrated
 float channelMax[16];
 

flix/time.ino

@@ -6,7 +6,7 @@
 float loopRate; // Hz
 
 void step() {
-	float now = micros() / 1000000.0;
+	double now = micros() / 1000000.0;
 	dt = now - t;
 	t = now;
 
@@ -18,7 +18,7 @@ void step() {
 }
 
 void computeLoopRate() {
-	static float windowStart = 0;
+	static double windowStart = 0;
 	static uint32_t rate = 0;
 	rate++;
 	if (t - windowStart >= 1) { // 1 second window

gazebo/flix.h

@@ -12,7 +12,7 @@
 
 #define WIFI_ENABLED 1
 
-float t = NAN;
+double t = NAN;
 float dt;
 float motors[4];
 int16_t channels[16]; // raw rc channels