Trying to get rid of magic PWM numbers

src/drivers/drv_pwm_output.h

@@ -64,6 +64,26 @@ __BEGIN_DECLS
  */
 #define PWM_OUTPUT_MAX_CHANNELS	16
 
+/**
+ * Minimum PWM in us
+ */
+#define PWM_MIN 900
+
+/**
+ * Highest PWM allowed as the minimum PWM
+ */
+#define PWM_HIGHEST_MIN 1300
+
+/**
+ * Maximum PWM in us
+ */
+#define PWM_MAX 2100
+
+/**
+ * Lowest PWM allowed as the maximum PWM
+ */
+#define PWM_LOWEST_MAX 1700
+
 /**
  * Servo output signal type, value is actual servo output pulse
  * width in microseconds.

src/drivers/px4io/px4io.cpp

@@ -1818,7 +1818,7 @@ PX4IO::ioctl(file * /*filep*/, int cmd, unsigned long arg)
 
 		/* TODO: we could go lower for e.g. TurboPWM */
 		unsigned channel = cmd - PWM_SERVO_SET(0);
-		if ((channel >= _max_actuators) || (arg < 900) || (arg > 2100)) {
+		if ((channel >= _max_actuators) || (arg < PWM_MIN) || (arg > PWM_MAX)) {
 			ret = -EINVAL;
 		} else {
 			/* send a direct PWM value */
@@ -2402,8 +2402,8 @@ px4io_main(int argc, char *argv[])
 			/* set channel to commandline argument or to 900 for non-provided channels */
 			if (argc > i + 2) {
 				failsafe[i] = atoi(argv[i+2]);
-				if (failsafe[i] < 800 || failsafe[i] > 2200) {
-					errx(1, "value out of range of 800 < value < 2200. Aborting.");
+				if (failsafe[i] < PWM_MIN || failsafe[i] > PWM_AX) {
+					errx(1, "value out of range of %d < value < %d. Aborting.", PWM_MIN, PWM_MAX);
 				}
 			} else {
 				/* a zero value will result in stopping to output any pulse */

src/modules/px4iofirmware/mixer.cpp

@@ -242,8 +242,8 @@ mixer_tick(void)
 
 				case ESC_RAMP:
 					r_page_servos[i] = (outputs[i]
-					 * (ramp_promille*r_page_servo_control_max[i] + (1000-ramp_promille)*2100 - ramp_promille*r_page_servo_control_min[i] - (1000-ramp_promille)*900)/2/1000
-					 + (ramp_promille*r_page_servo_control_max[i] + (1000-ramp_promille)*2100 + ramp_promille*r_page_servo_control_min[i] + (1000-ramp_promille)*900)/2/1000);
+					 * (ramp_promille*r_page_servo_control_max[i] + (1000-ramp_promille)*PWM_MAX - ramp_promille*r_page_servo_control_min[i] - (1000-ramp_promille)*PWM_MIN)/2/1000
+					 + (ramp_promille*r_page_servo_control_max[i] + (1000-ramp_promille)*PWM_MAX + ramp_promille*r_page_servo_control_min[i] + (1000-ramp_promille)*PWM_MIN)/2/1000);
 				break;
 
 				case ESC_ON:

src/modules/px4iofirmware/registers.c

@@ -207,7 +207,7 @@ uint16_t		r_page_servo_failsafe[PX4IO_SERVO_COUNT] = { 0 };
  * minimum PWM values when armed
  *
  */
-uint16_t		r_page_servo_control_min[PX4IO_SERVO_COUNT] = { 900, 900, 900, 900, 900, 900, 900, 900 };
+uint16_t		r_page_servo_control_min[PX4IO_SERVO_COUNT] = { PWM_MIN, PWM_MIN, PWM_MIN, PWM_MIN, PWM_MIN, PWM_MIN, PWM_MIN, PWM_MIN };
 
 /**
  * PAGE 107
@@ -215,7 +215,7 @@ uint16_t		r_page_servo_control_min[PX4IO_SERVO_COUNT] = { 900, 900, 900, 900, 90
  * maximum PWM values when armed
  *
  */
-uint16_t		r_page_servo_control_max[PX4IO_SERVO_COUNT] = { 2100, 2100, 2100, 2100, 2100, 2100, 2100, 2100 };
+uint16_t		r_page_servo_control_max[PX4IO_SERVO_COUNT] = { PWM_MAX, PWM_MAX, PWM_MAX, PWM_MAX, PWM_MAX, PWM_MAX, PWM_MAX, PWM_MAX };
 
 /**
  * PAGE 108
@@ -223,7 +223,7 @@ uint16_t		r_page_servo_control_max[PX4IO_SERVO_COUNT] = { 2100, 2100, 2100, 2100
  * disarmed PWM values for difficult ESCs
  *
  */
-uint16_t		r_page_servo_disarmed[PX4IO_SERVO_COUNT] = { 900, 900, 900, 900, 900, 900, 900, 900 };
+uint16_t		r_page_servo_disarmed[PX4IO_SERVO_COUNT] = { 0, 0, 0, 0, 0, 0, 0, 0 };
 
 int
 registers_set(uint8_t page, uint8_t offset, const uint16_t *values, unsigned num_values)
@@ -295,10 +295,10 @@ registers_set(uint8_t page, uint8_t offset, const uint16_t *values, unsigned num
 
 			if (*values == 0) {
 				/* ignore 0 */
-			} else if (*values > 1200) {
-				r_page_servo_control_min[offset] = 1200;
-			} else if (*values < 900) {
-				r_page_servo_control_min[offset] = 900;
+			} else if (*values > PWM_HIGHEST_MIN) {
+				r_page_servo_control_min[offset] = PWM_HIGHEST_MIN;
+			} else if (*values < PWM_MIN) {
+				r_page_servo_control_min[offset] = PWM_MIN;
 			} else {
 				r_page_servo_control_min[offset] = *values;
 			}
@@ -316,10 +316,10 @@ registers_set(uint8_t page, uint8_t offset, const uint16_t *values, unsigned num
 
 			if (*values == 0) {
 				/* ignore 0 */
-			} else if (*values > 2100) {
-				r_page_servo_control_max[offset] = 2100;
-			} else if (*values < 1800) {
-				r_page_servo_control_max[offset] = 1800;
+			} else if (*values > PWM_MAX) {
+				r_page_servo_control_max[offset] = PWM_MAX;
+			} else if (*values < PWM_LOWEST_MAX) {
+				r_page_servo_control_max[offset] = PWM_LOWEST_MAX;
 			} else {
 				r_page_servo_control_max[offset] = *values;
 			}
@@ -337,10 +337,10 @@ registers_set(uint8_t page, uint8_t offset, const uint16_t *values, unsigned num
 
 			if (*values == 0) {
 				/* ignore 0 */
-			} else if (*values < 900) {
-				r_page_servo_disarmed[offset] = 900;
-			} else if (*values > 2100) {
-				r_page_servo_disarmed[offset] = 2100;
+			} else if (*values < PWM_MIN) {
+				r_page_servo_disarmed[offset] = PWM_MIN;
+			} else if (*values > PWM_MAX) {
+				r_page_servo_disarmed[offset] = PWM_MAX;
 			} else {
 				r_page_servo_disarmed[offset] = *values;
 			}