crazyflie: fix PWM channel ordering

Channels belonging to a certain timer were not all grouped together.
This is required by the .first_channel_index and .last_channel_index data
members.

We introduce a new mixer geometry to solve the problem.

ROMFS/px4fmu_common/init.d/airframes/4900_crazyflie

@@ -17,7 +17,7 @@
 #
 sh /etc/init.d/rc.mc_defaults
 
-set MIXER quad_x
+set MIXER quad_x_cw
 set PWM_OUT 1234
 if [ $AUTOCNF = yes ]
 then

ROMFS/px4fmu_common/mixers/CMakeLists.txt

@@ -71,6 +71,7 @@ px4_add_romfs_files(
 	quad_+_vtol.main.mix
 	quad_w.main.mix
 	quad_x.main.mix
+	quad_x_cw.main.mix
 	quad_x_vtol.main.mix
 	stampede.main.mix
 	tri_y_yaw-.main.mix

ROMFS/px4fmu_common/mixers/quad_x_cw.main.mix

@@ -0,0 +1,5 @@
+# @board px4_fmu-v2 exclude
+# Quad X with clock-wise motor assigment
+
+R: 4xcw 10000 10000 10000 0
+

boards/bitcraze/crazyflie/src/timer_config.c

@@ -92,6 +92,15 @@ __EXPORT const timer_io_channels_t timer_io_channels[MAX_TIMER_IO_CHANNELS] = {
 		.ccr_offset = STM32_GTIM_CCR2_OFFSET,
 		.masks  = GTIM_SR_CC2IF | GTIM_SR_CC2OF
 	},
+	{
+		// M2
+		.gpio_out = GPIO_TIM2_CH4OUT,
+		.gpio_in = GPIO_TIM2_CH4IN,
+		.timer_index = 0,
+		.timer_channel = 4,
+		.ccr_offset = STM32_GTIM_CCR4_OFFSET,
+		.masks  = GTIM_SR_CC4IF | GTIM_SR_CC4OF
+	},
 	{
 		// M3
 		.gpio_out = GPIO_TIM2_CH1OUT,
@@ -110,13 +119,4 @@ __EXPORT const timer_io_channels_t timer_io_channels[MAX_TIMER_IO_CHANNELS] = {
 		.ccr_offset = STM32_GTIM_CCR4_OFFSET,
 		.masks  = GTIM_SR_CC4IF | GTIM_SR_CC4OF
 	},
-	{
-		// M2
-		.gpio_out = GPIO_TIM2_CH4OUT,
-		.gpio_in = GPIO_TIM2_CH4IN,
-		.timer_index = 0,
-		.timer_channel = 4,
-		.ccr_offset = STM32_GTIM_CCR4_OFFSET,
-		.masks  = GTIM_SR_CC4IF | GTIM_SR_CC4OF
-	},
 };

src/lib/mixer/MultirotorMixer/CMakeLists.txt

@@ -48,6 +48,7 @@ set(geometry_files
 	quad_s250aq.toml
 	quad_vtail.toml
 	quad_wide.toml
+	quad_x_cw.toml
 	quad_x.toml
 	quad_x_pusher.toml
 	quad_y.toml

src/lib/mixer/MultirotorMixer/geometries/quad_x_cw.toml

@@ -0,0 +1,30 @@
+# Generic Quadcopter in X configuration
+# with clock-wise motor numbering
+
+[info]
+key = "4xcw"
+description =  "Quadcopter in X configuration with clock-wise motor numbering"
+
+[rotor_default]
+direction = "CW"
+axis      = [0.0, 0.0, -1.0]
+Ct        = 1.0
+Cm        = 0.05
+
+[[rotors]]
+name      = "front_right"
+position  = [0.707107, 0.707107, 0.0]
+direction = "CCW"
+
+[[rotors]]
+name     = "rear_right"
+position = [-0.707107, 0.707107, 0.0]
+
+[[rotors]]
+name      = "rear_left"
+position  = [-0.707107, -0.707107, 0.0]
+direction = "CCW"
+
+[[rotors]]
+name     = "front_left"
+position = [0.707107, -0.707107, 0.0]