Merge remote-tracking branch 'upstream/master' into fw_staging_ouputlimit_master

8 files changed, 114 insertions, 192 deletions

diff --git a/src/modules/px4iofirmware/i2c.c b/src/modules/px4iofirmware/i2c.c
index 10aeb5c9f..79b6546b3 100644
--- a/src/modules/px4iofirmware/i2c.c
+++ b/src/modules/px4iofirmware/i2c.c
@@ -149,12 +149,6 @@ interface_init(void)
 #endif
 }
 
-void
-interface_tick()
-{
-}
-
-
 /*
   reset the I2C bus
   used to recover from lockups
diff --git a/src/modules/px4iofirmware/mixer.cpp b/src/modules/px4iofirmware/mixer.cpp
index 30aff7d20..05897b4ce 100644
--- a/src/modules/px4iofirmware/mixer.cpp
+++ b/src/modules/px4iofirmware/mixer.cpp
@@ -47,6 +47,7 @@
 #include <drivers/drv_pwm_output.h>
 #include <drivers/drv_hrt.h>
 
+#include <systemlib/pwm_limit/pwm_limit.h>
 #include <systemlib/mixer/mixer.h>
 
 extern "C" {
@@ -59,12 +60,6 @@ extern "C" {
  */
 #define FMU_INPUT_DROP_LIMIT_US		200000
 
-/*
- * Time that the ESCs need to initialize
- */
- #define ESC_INIT_TIME_US		1000000
- #define ESC_RAMP_TIME_US		2000000
-
 /* XXX need to move the RC_CHANNEL_FUNCTION out of rc_channels.h and into systemlib */
 #define ROLL     0
 #define PITCH    1
@@ -76,15 +71,6 @@ extern "C" {
 static bool mixer_servos_armed = false;
 static bool should_arm = false;
 static bool should_always_enable_pwm = false;
-static uint64_t esc_init_time;
-
-enum esc_state_e {
-	ESC_OFF,
-	ESC_INIT,
-	ESC_RAMP,
-	ESC_ON
-};
-static esc_state_e esc_state;
 
 /* selected control values and count for mixing */
 enum mixer_source {
@@ -166,6 +152,30 @@ mixer_tick(void)
 	}
 
 	/*
+	 * Decide whether the servos should be armed right now.
+	 *
+	 * We must be armed, and we must have a PWM source; either raw from
+	 * FMU or from the mixer.
+	 *
+	 * XXX correct behaviour for failsafe may require an additional case
+	 * here.
+	 */
+	should_arm = (
+		/* IO initialised without error */   (r_status_flags & PX4IO_P_STATUS_FLAGS_INIT_OK)
+		/* and IO is armed */ 		  && (r_status_flags & PX4IO_P_STATUS_FLAGS_SAFETY_OFF)
+		/* and FMU is armed */ 		  && (
+							    ((r_setup_arming & PX4IO_P_SETUP_ARMING_FMU_ARMED)
+		/* and there is valid input via or mixer */         &&   (r_status_flags & PX4IO_P_STATUS_FLAGS_MIXER_OK) )
+		/* or direct PWM is set */               || (r_status_flags & PX4IO_P_STATUS_FLAGS_RAW_PWM)
+		/* or failsafe was set manually */	 || (r_setup_arming & PX4IO_P_SETUP_ARMING_FAILSAFE_CUSTOM)
+						     )
+	);
+
+	should_always_enable_pwm = (r_setup_arming & PX4IO_P_SETUP_ARMING_ALWAYS_PWM_ENABLE)
+						&& (r_status_flags & PX4IO_P_STATUS_FLAGS_INIT_OK)
+						&& (r_status_flags & PX4IO_P_STATUS_FLAGS_FMU_OK);
+
+	/*
 	 * Run the mixers.
 	 */
 	if (source == MIX_FAILSAFE) {
@@ -184,107 +194,15 @@ mixer_tick(void)
 		float	outputs[PX4IO_SERVO_COUNT];
 		unsigned mixed;
 
-		uint16_t ramp_promille;
-
-		/* update esc init state, but only if we are truely armed and not just PWM enabled */
-		if (mixer_servos_armed && should_arm) {
-
-			switch (esc_state) {
-
-				/* after arming, some ESCs need an initalization period, count the time from here */
-				case ESC_OFF:
-					esc_init_time = hrt_absolute_time();
-					esc_state = ESC_INIT;
-				break;
-
-				/* after waiting long enough for the ESC initialization, we can start with the ramp to start the ESCs */
-				case ESC_INIT:
-					if (hrt_elapsed_time(&esc_init_time) > ESC_INIT_TIME_US) {
-						esc_state = ESC_RAMP;
-					}
-				break;
-
-				/* then ramp until the min speed is reached */
-				case ESC_RAMP:
-					if (hrt_elapsed_time(&esc_init_time) > (ESC_INIT_TIME_US + ESC_RAMP_TIME_US)) {
-						esc_state = ESC_ON;
-					}
-				break;
-
-				case ESC_ON:
-				default:
-
-				break;
-			}
-		} else {
-			esc_state = ESC_OFF;
-		}
-
-		/* do the calculations during the ramp for all at once */
-		if (esc_state == ESC_RAMP) {
-			ramp_promille = (1000*(hrt_elapsed_time(&esc_init_time)-ESC_INIT_TIME_US))/ESC_RAMP_TIME_US;
-		}
-
-
 		/* mix */
 		mixed = mixer_group.mix(&outputs[0], PX4IO_SERVO_COUNT);
 
-		/* scale to PWM and update the servo outputs as required */
-		for (unsigned i = 0; i < mixed; i++) {
-
-			/* save actuator values for FMU readback */
-			r_page_actuators[i] = FLOAT_TO_REG(outputs[i]);
-
-			switch (esc_state) {
-				case ESC_INIT:
-					r_page_servos[i] = (outputs[i] * 600 + 1500);
-				break;
-
-				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);
-				break;
-
-				case ESC_ON:
-					r_page_servos[i] = (outputs[i]
-					 * (r_page_servo_control_max[i] - r_page_servo_control_min[i])/2
-					 + (r_page_servo_control_max[i] + r_page_servo_control_min[i])/2);
-				break;
+		pwm_limit_calc(should_arm, mixed, r_page_servo_disarmed, r_page_servo_control_min, r_page_servo_control_max, outputs, r_page_servos, &pwm_limit);
 
-				case ESC_OFF:
-				default:
-				break;
-			}
-		}
 		for (unsigned i = mixed; i < PX4IO_SERVO_COUNT; i++)
 			r_page_servos[i] = 0;
 	}
 
-	/*
-	 * Decide whether the servos should be armed right now.
-	 *
-	 * We must be armed, and we must have a PWM source; either raw from
-	 * FMU or from the mixer.
-	 *
-	 * XXX correct behaviour for failsafe may require an additional case
-	 * here.
-	 */
-	should_arm = (
-		/* IO initialised without error */   (r_status_flags & PX4IO_P_STATUS_FLAGS_INIT_OK)
-		/* and IO is armed */ 		  && (r_status_flags & PX4IO_P_STATUS_FLAGS_SAFETY_OFF)
-		/* and FMU is armed */ 		  && (
-							    ((r_setup_arming & PX4IO_P_SETUP_ARMING_FMU_ARMED)
-		/* and there is valid input via or mixer */         &&   (r_status_flags & PX4IO_P_STATUS_FLAGS_MIXER_OK) )
-		/* or direct PWM is set */               || (r_status_flags & PX4IO_P_STATUS_FLAGS_RAW_PWM)
-		/* or failsafe was set manually */	 || (r_setup_arming & PX4IO_P_SETUP_ARMING_FAILSAFE_CUSTOM)
-						     )
-	);
-
-	should_always_enable_pwm = (r_setup_arming & PX4IO_P_SETUP_ARMING_ALWAYS_PWM_ENABLE)
-						&& (r_status_flags & PX4IO_P_STATUS_FLAGS_INIT_OK)
-						&& (r_status_flags & PX4IO_P_STATUS_FLAGS_FMU_OK);
-
 	if ((should_arm || should_always_enable_pwm) && !mixer_servos_armed) {
 		/* need to arm, but not armed */
 		up_pwm_servo_arm(true);
@@ -298,7 +216,6 @@ mixer_tick(void)
 		mixer_servos_armed = false;
 		r_status_flags &= ~(PX4IO_P_STATUS_FLAGS_OUTPUTS_ARMED);
 		isr_debug(5, "> PWM disabled");
-
 	}
 
 	if (mixer_servos_armed && should_arm) {
@@ -307,9 +224,9 @@ mixer_tick(void)
 			up_pwm_servo_set(i, r_page_servos[i]);
 
 	} else if (mixer_servos_armed && should_always_enable_pwm) {
-		/* set the idle servo outputs. */
+		/* set the disarmed servo outputs. */
 		for (unsigned i = 0; i < PX4IO_SERVO_COUNT; i++)
-			up_pwm_servo_set(i, r_page_servo_idle[i]);
+			up_pwm_servo_set(i, r_page_servo_disarmed[i]);
 	}
 }
 
diff --git a/src/modules/px4iofirmware/module.mk b/src/modules/px4iofirmware/module.mk
index 59f470a94..01869569f 100644
--- a/src/modules/px4iofirmware/module.mk
+++ b/src/modules/px4iofirmware/module.mk
@@ -14,6 +14,7 @@ SRCS		= adc.c \
 		  ../systemlib/mixer/mixer_group.cpp \
 		  ../systemlib/mixer/mixer_multirotor.cpp \
 		  ../systemlib/mixer/mixer_simple.cpp \
+		  ../systemlib/pwm_limit/pwm_limit.c
 
 ifeq ($(BOARD),px4io-v1)
 SRCS		+= i2c.c
diff --git a/src/modules/px4iofirmware/protocol.h b/src/modules/px4iofirmware/protocol.h
index 0e2cd1689..5e5396782 100644
--- a/src/modules/px4iofirmware/protocol.h
+++ b/src/modules/px4iofirmware/protocol.h
@@ -220,8 +220,8 @@ enum {							/* DSM bind states */
 /* PWM maximum values for certain ESCs */
 #define PX4IO_PAGE_CONTROL_MAX_PWM		107	/* 0..CONFIG_ACTUATOR_COUNT-1 */
 
-/* PWM idle values that are active, even when SAFETY_SAFE */
-#define PX4IO_PAGE_IDLE_PWM		108	/* 0..CONFIG_ACTUATOR_COUNT-1 */
+/* PWM disarmed values that are active, even when SAFETY_SAFE */
+#define PX4IO_PAGE_DISARMED_PWM		108	/* 0..CONFIG_ACTUATOR_COUNT-1 */
 
 /**
  * As-needed mixer data upload.
diff --git a/src/modules/px4iofirmware/px4io.c b/src/modules/px4iofirmware/px4io.c
index e70b3fe88..ff9eecd74 100644
--- a/src/modules/px4iofirmware/px4io.c
+++ b/src/modules/px4iofirmware/px4io.c
@@ -50,6 +50,7 @@
 #include <drivers/drv_hrt.h>
 
 #include <systemlib/perf_counter.h>
+#include <systemlib/pwm_limit/pwm_limit.h>
 
 #include <stm32_uart.h>
 
@@ -64,6 +65,8 @@ struct sys_state_s 	system_state;
 
 static struct hrt_call serial_dma_call;
 
+pwm_limit_t pwm_limit;
+
 /*
  * a set of debug buffers to allow us to send debug information from ISRs
  */
@@ -159,9 +162,6 @@ user_start(int argc, char *argv[])
 	/* start the FMU interface */
 	interface_init();
 
-	/* add a performance counter for the interface */
-	perf_counter_t interface_perf = perf_alloc(PC_ELAPSED, "interface");
-
 	/* add a performance counter for mixing */
 	perf_counter_t mixer_perf = perf_alloc(PC_ELAPSED, "mix");
 
@@ -174,6 +174,9 @@ user_start(int argc, char *argv[])
 	struct mallinfo minfo = mallinfo();
 	lowsyslog("MEM: free %u, largest %u\n", minfo.mxordblk, minfo.fordblks);
 
+	/* initialize PWM limit lib */
+	pwm_limit_init(&pwm_limit);
+
 #if 0
 	/* not enough memory, lock down */
 	if (minfo.mxordblk < 500) {
@@ -203,11 +206,6 @@ user_start(int argc, char *argv[])
 		/* track the rate at which the loop is running */
 		perf_count(loop_perf);
 
-		/* kick the interface */
-		perf_begin(interface_perf);
-		interface_tick();
-		perf_end(interface_perf);
-
 		/* kick the mixer */
 		perf_begin(mixer_perf);
 		mixer_tick();
@@ -218,6 +216,7 @@ user_start(int argc, char *argv[])
 		controls_tick();
 		perf_end(controls_perf);
 
+#if 0
 		/* check for debug activity */
 		show_debug_messages();
 
@@ -234,6 +233,7 @@ user_start(int argc, char *argv[])
 				  (unsigned)minfo.mxordblk);
 			last_debug_time = hrt_absolute_time();
 		}
+#endif
 	}
 }
 
diff --git a/src/modules/px4iofirmware/px4io.h b/src/modules/px4iofirmware/px4io.h
index 66c4ca906..4fea0288c 100644
--- a/src/modules/px4iofirmware/px4io.h
+++ b/src/modules/px4iofirmware/px4io.h
@@ -46,6 +46,8 @@
 
 #include "protocol.h"
 
+#include <systemlib/pwm_limit/pwm_limit.h>
+
 /*
  * Constants and limits.
  */
@@ -80,7 +82,7 @@ extern uint16_t			r_page_rc_input_config[]; /* PX4IO_PAGE_RC_INPUT_CONFIG */
 extern uint16_t			r_page_servo_failsafe[]; /* PX4IO_PAGE_FAILSAFE_PWM */
 extern uint16_t			r_page_servo_control_min[]; /* PX4IO_PAGE_CONTROL_MIN_PWM */
 extern uint16_t			r_page_servo_control_max[]; /* PX4IO_PAGE_CONTROL_MAX_PWM */
-extern uint16_t			r_page_servo_idle[];	/* PX4IO_PAGE_IDLE_PWM */
+extern uint16_t			r_page_servo_disarmed[];	/* PX4IO_PAGE_DISARMED_PWM */
 
 /*
  * Register aliases.
@@ -123,6 +125,11 @@ struct sys_state_s {
 extern struct sys_state_s system_state;
 
 /*
+ * PWM limit structure
+ */
+extern pwm_limit_t pwm_limit;
+
+/*
  * GPIO handling.
  */
 #define LED_BLUE(_s)			stm32_gpiowrite(GPIO_LED1, !(_s))
diff --git a/src/modules/px4iofirmware/registers.c b/src/modules/px4iofirmware/registers.c
index 9d9ef7c6d..40597adf1 100644
--- a/src/modules/px4iofirmware/registers.c
+++ b/src/modules/px4iofirmware/registers.c
@@ -199,7 +199,7 @@ uint16_t		r_page_rc_input_config[PX4IO_CONTROL_CHANNELS * PX4IO_P_RC_CONFIG_STRI
  * 
  * Disable pulses as default.
  */
-uint16_t		r_page_servo_failsafe[PX4IO_SERVO_COUNT] = { 0 };
+uint16_t		r_page_servo_failsafe[PX4IO_SERVO_COUNT] = { 0, 0, 0, 0, 0, 0, 0, 0 };
 
 /**
  * PAGE 106
@@ -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
@@ -215,15 +215,15 @@ 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
  *
- * idle PWM values for difficult ESCs
+ * disarmed PWM values for difficult ESCs
  *
  */
-uint16_t		r_page_servo_idle[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)
@@ -276,8 +276,15 @@ registers_set(uint8_t page, uint8_t offset, const uint16_t *values, unsigned num
 		/* copy channel data */
 		while ((offset < PX4IO_SERVO_COUNT) && (num_values > 0)) {
 
-			/* XXX range-check value? */
-			r_page_servo_failsafe[offset] = *values;
+			if (*values == 0) {
+				/* ignore 0 */
+			} else if (*values < PWM_MIN) {
+				r_page_servo_failsafe[offset] = PWM_MIN;
+			} else if (*values > PWM_MAX) {
+				r_page_servo_failsafe[offset] = PWM_MAX;
+			} else {
+				r_page_servo_failsafe[offset] = *values;
+			}
 
 			/* flag the failsafe values as custom */
 			r_setup_arming |= PX4IO_P_SETUP_ARMING_FAILSAFE_CUSTOM;
@@ -293,16 +300,15 @@ registers_set(uint8_t page, uint8_t offset, const uint16_t *values, unsigned num
 		/* copy channel data */
 		while ((offset < PX4IO_SERVO_COUNT) && (num_values > 0)) {
 
-			if (*values == 0)
-				/* set to default */
-				r_page_servo_control_min[offset] = 900;
-
-			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 == 0) {
+				/* ignore 0 */
+			} 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;
+			}
 
 			offset++;
 			num_values--;
@@ -315,16 +321,15 @@ registers_set(uint8_t page, uint8_t offset, const uint16_t *values, unsigned num
 		/* copy channel data */
 		while ((offset < PX4IO_SERVO_COUNT) && (num_values > 0)) {
 
-			if (*values == 0)
-				/* set to default */
-				r_page_servo_control_max[offset] = 2100;
-
-			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 == 0) {
+				/* ignore 0 */
+			} 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;
+			}
 
 			offset++;
 			num_values--;
@@ -332,28 +337,40 @@ registers_set(uint8_t page, uint8_t offset, const uint16_t *values, unsigned num
 		}
 		break;
 
-	case PX4IO_PAGE_IDLE_PWM:
-
-		/* copy channel data */
-		while ((offset < PX4IO_SERVO_COUNT) && (num_values > 0)) {
-
-			if (*values == 0)
-				/* set to default */
-				r_page_servo_idle[offset] = 0;
-
-			else if (*values < 900)
-				r_page_servo_idle[offset] = 900;
-			else if (*values > 2100)
-				r_page_servo_idle[offset] = 2100;
-			else
-				r_page_servo_idle[offset] = *values;
+	case PX4IO_PAGE_DISARMED_PWM:
+		{
+			/* flag for all outputs */
+			bool all_disarmed_off = true;
+
+			/* copy channel data */
+			while ((offset < PX4IO_SERVO_COUNT) && (num_values > 0)) {
+
+				if (*values == 0) {
+					/* 0 means disabling always PWM */
+					r_page_servo_disarmed[offset] = 0;
+				} else if (*values < PWM_MIN) {
+					r_page_servo_disarmed[offset] = PWM_MIN;
+					all_disarmed_off = false;
+				} else if (*values > PWM_MAX) {
+					r_page_servo_disarmed[offset] = PWM_MAX;
+					all_disarmed_off = false;
+				} else {
+					r_page_servo_disarmed[offset] = *values;
+					all_disarmed_off = false;
+				}
 
-			/* flag the failsafe values as custom */
-			r_setup_arming |= PX4IO_P_SETUP_ARMING_ALWAYS_PWM_ENABLE;
+				offset++;
+				num_values--;
+				values++;
+			}
 
-			offset++;
-			num_values--;
-			values++;
+			if (all_disarmed_off) {
+				/* disable PWM output if disarmed */
+				r_setup_arming &= ~(PX4IO_P_SETUP_ARMING_ALWAYS_PWM_ENABLE);
+			} else {
+				/* enable PWM output always */
+				r_setup_arming |= PX4IO_P_SETUP_ARMING_ALWAYS_PWM_ENABLE;
+			}
 		}
 		break;
 
@@ -767,8 +784,8 @@ registers_get(uint8_t page, uint8_t offset, uint16_t **values, unsigned *num_val
 	case PX4IO_PAGE_CONTROL_MAX_PWM:
 		SELECT_PAGE(r_page_servo_control_max);
 		break;
-	case PX4IO_PAGE_IDLE_PWM:
-		SELECT_PAGE(r_page_servo_idle);
+	case PX4IO_PAGE_DISARMED_PWM:
+		SELECT_PAGE(r_page_servo_disarmed);
 		break;
 
 	default:
diff --git a/src/modules/px4iofirmware/serial.c b/src/modules/px4iofirmware/serial.c
index 94d7407df..e9adc8cd6 100644
--- a/src/modules/px4iofirmware/serial.c
+++ b/src/modules/px4iofirmware/serial.c
@@ -74,9 +74,6 @@ static DMA_HANDLE	rx_dma;
 static int		serial_interrupt(int irq, void *context);
 static void		dma_reset(void);
 
-/* if we spend this many ticks idle, reset the DMA */
-static unsigned		idle_ticks;
-
 static struct IOPacket	dma_packet;
 
 /* serial register accessors */
@@ -150,16 +147,6 @@ interface_init(void)
 	debug("serial init");
 }
 
-void
-interface_tick()
-{
-	/* XXX look for stuck/damaged DMA and reset? */
-	if (idle_ticks++ > 100) {
-		dma_reset();
-		idle_ticks = 0;
-	}
-}
-
 static void
 rx_handle_packet(void)
 {
@@ -230,9 +217,6 @@ rx_dma_callback(DMA_HANDLE handle, uint8_t status, void *arg)
 	/* disable UART DMA */
 	rCR3 &= ~(USART_CR3_DMAT | USART_CR3_DMAR);
 
-	/* reset the idle counter */
-	idle_ticks = 0;
-
 	/* handle the received packet */
 	rx_handle_packet();
 
@@ -308,6 +292,7 @@ serial_interrupt(int irq, void *context)
 
 			/* it was too short - possibly truncated */
 			perf_count(pc_badidle);
+			dma_reset();
 			return 0;
 		}
 
@@ -343,7 +328,8 @@ dma_reset(void)
 		sizeof(dma_packet),
 		DMA_CCR_MINC		|
 		DMA_CCR_PSIZE_8BITS	|
-		DMA_CCR_MSIZE_8BITS);
+		DMA_CCR_MSIZE_8BITS     |
+		DMA_CCR_PRIVERYHI);
 
 	/* start receive DMA ready for the next packet */
 	stm32_dmastart(rx_dma, rx_dma_callback, NULL, false);