Clean up RC related metadata, put everything into the RC data page. This ensures atomic reads, makes the reads more efficient and allows for some headroom for more RC flags. The IO driver side is updated as well, however, these flags are not published yet.

src/drivers/px4io/px4io.cpp

@@ -1763,6 +1763,7 @@ PX4IO::print_status()
 	printf("%u bytes free\n",
 	       io_reg_get(PX4IO_PAGE_STATUS, PX4IO_P_STATUS_FREEMEM));
 	uint16_t flags = io_reg_get(PX4IO_PAGE_STATUS, PX4IO_P_STATUS_FLAGS);
+	uint16_t io_status_flags = flags;
 	printf("status 0x%04x%s%s%s%s%s%s%s%s%s%s%s%s%s\n",
 	       flags,
 	       ((flags & PX4IO_P_STATUS_FLAGS_OUTPUTS_ARMED) ? " OUTPUTS_ARMED" : ""),
@@ -1770,8 +1771,6 @@ PX4IO::print_status()
 	       ((flags & PX4IO_P_STATUS_FLAGS_OVERRIDE) ? " OVERRIDE" : ""),
 	       ((flags & PX4IO_P_STATUS_FLAGS_RC_OK)    ? " RC_OK" : " RC_FAIL"),
 	       ((flags & PX4IO_P_STATUS_FLAGS_RC_PPM)   ? " PPM" : ""),
-	       (((flags & PX4IO_P_STATUS_FLAGS_RC_DSM) && (!(flags & PX4IO_P_STATUS_FLAGS_RC_DSM11))) ? " DSM10" : ""),
-	       (((flags & PX4IO_P_STATUS_FLAGS_RC_DSM) && (flags & PX4IO_P_STATUS_FLAGS_RC_DSM11)) ? " DSM11" : ""),
 	       ((flags & PX4IO_P_STATUS_FLAGS_RC_SBUS)  ? " SBUS" : ""),
 	       ((flags & PX4IO_P_STATUS_FLAGS_FMU_OK)   ? " FMU_OK" : " FMU_FAIL"),
 	       ((flags & PX4IO_P_STATUS_FLAGS_RAW_PWM)  ? " RAW_PWM_PASSTHROUGH" : ""),
@@ -1824,6 +1823,11 @@ PX4IO::print_status()
 	printf("\n");
 	uint16_t raw_inputs = io_reg_get(PX4IO_PAGE_RAW_RC_INPUT, PX4IO_P_RAW_RC_COUNT);
 	printf("%d raw R/C inputs", raw_inputs);
+	flags = io_reg_get(PX4IO_PAGE_RAW_RC_INPUT, PX4IO_P_RAW_RC_FLAGS);
+	printf("status 0x%04x%s", flags,
+		(((io_status_flags & PX4IO_P_STATUS_FLAGS_RC_DSM) && (!(flags & PX4IO_P_RAW_RC_FLAGS_RC_DSM11))) ? " DSM10" : ""),
+		(((io_status_flags & PX4IO_P_STATUS_FLAGS_RC_DSM) && (flags & PX4IO_P_RAW_RC_FLAGS_RC_DSM11)) ? " DSM11" : "")
+	       );
 
 	for (unsigned i = 0; i < raw_inputs; i++)
 		printf(" %u", io_reg_get(PX4IO_PAGE_RAW_RC_INPUT, PX4IO_P_RAW_RC_BASE + i));
@@ -1831,7 +1835,7 @@ PX4IO::print_status()
 	printf("\n");
 
 	if ((flags & PX4IO_P_STATUS_FLAGS_RC_PPM)) {
-		int frame_len = io_reg_get(PX4IO_PAGE_STATUS, PX4IO_P_STATUS_RC_DATA);
+		int frame_len = io_reg_get(PX4IO_PAGE_RAW_RC_INPUT, PX4IO_P_RAW_RC_DATA);
 		printf("RC data (PPM frame len) %u us\n", frame_len);
 
 		if ((frame_len - raw_inputs * 2000 - 3000) < 0) {

src/modules/px4iofirmware/controls.c

@@ -97,28 +97,57 @@ controls_tick() {
 	/* receive signal strenght indicator (RSSI). 0 = no connection, 255: perfect connection */
 	uint16_t rssi = 0;
 
+#ifdef ADC_RSSI
+	unsigned counts = adc_measure(ADC_RSSI);
+	if (counts != 0xffff) {
+		/* use 1:1 scaling on 3.3V ADC input */
+		unsigned mV = counts * 3300 / 4096;
+
+		/* scale to 0..253 */
+		rssi = mV / 13;
+	}
+#endif
+
 	perf_begin(c_gather_dsm);
 	uint16_t temp_count = r_raw_rc_count;
 	bool dsm_updated = dsm_input(r_raw_rc_values, &temp_count);
 	if (dsm_updated) {
-		r_status_flags |= PX4IO_P_STATUS_FLAGS_RC_DSM;
+		r_raw_rc_flags |= PX4IO_P_STATUS_FLAGS_RC_DSM;
 		r_raw_rc_count = temp_count & 0x7fff;
 		if (temp_count & 0x8000)
-			r_status_flags |= PX4IO_P_STATUS_FLAGS_RC_DSM11;
+			r_raw_rc_flags |= PX4IO_P_RAW_RC_FLAGS_RC_DSM11;
 		else
-			r_status_flags &= ~PX4IO_P_STATUS_FLAGS_RC_DSM11;
+			r_raw_rc_flags &= ~PX4IO_P_RAW_RC_FLAGS_RC_DSM11;
 
-		rssi = 255;
 	}
 	perf_end(c_gather_dsm);
 
 	perf_begin(c_gather_sbus);
-	bool sbus_updated = sbus_input(r_raw_rc_values, &r_raw_rc_count, &rssi, PX4IO_RC_INPUT_CHANNELS);
 
 	bool sbus_status = (r_status_flags & PX4IO_P_STATUS_FLAGS_RC_SBUS);
 
+	bool sbus_failsafe, sbus_frame_drop;
+	bool sbus_updated = sbus_input(r_raw_rc_values, &r_raw_rc_count, &sbus_failsafe, &sbus_frame_drop, PX4IO_RC_INPUT_CHANNELS);
+
 	if (sbus_updated) {
 		r_status_flags |= PX4IO_P_STATUS_FLAGS_RC_SBUS;
+
+		rssi = 255;
+
+		if (sbus_frame_drop) {
+			r_raw_rc_flags |= PX4IO_P_RAW_RC_FLAGS_FRAME_DROP;
+			rssi = 100;
+		} else {
+			r_raw_rc_flags &= ~(PX4IO_P_RAW_RC_FLAGS_FRAME_DROP);
+		}
+
+		if (sbus_failsafe) {
+			r_raw_rc_flags |= PX4IO_P_RAW_RC_FLAGS_FAILSAFE;
+			rssi = 0;
+		} else {
+			r_raw_rc_flags &= ~(PX4IO_P_RAW_RC_FLAGS_FAILSAFE);
+		}
+
 	}
 
 	/* switch S.Bus output pin as needed */
@@ -136,12 +165,9 @@ controls_tick() {
 	 * disable the PPM decoder completely if we have S.bus signal.
 	 */
 	perf_begin(c_gather_ppm);
-	bool ppm_updated = ppm_input(r_raw_rc_values, &r_raw_rc_count, &r_page_status[PX4IO_P_STATUS_RC_DATA]);
+	bool ppm_updated = ppm_input(r_raw_rc_values, &r_raw_rc_count, &r_page_raw_rc_input[PX4IO_P_RAW_RC_DATA]);
 	if (ppm_updated) {
 
-		/* XXX sample RSSI properly here */
-		rssi = 255;
-
 		r_status_flags |= PX4IO_P_STATUS_FLAGS_RC_PPM;
 	}
 	perf_end(c_gather_ppm);
@@ -150,6 +176,9 @@ controls_tick() {
 	if (r_raw_rc_count > PX4IO_RC_INPUT_CHANNELS)
 		r_raw_rc_count = PX4IO_RC_INPUT_CHANNELS;
 
+	/* store RSSI */
+	r_page_raw_rc_input[PX4IO_P_RAW_RC_NRSSI] = rssi;
+
 	/*
 	 * In some cases we may have received a frame, but input has still
 	 * been lost.
@@ -247,7 +276,7 @@ controls_tick() {
 		 * This might happen if a protocol-based receiver returns an update
 		 * that contains no channels that we have mapped.
 		 */
-		if (assigned_channels == 0 || rssi == 0) {
+		if (assigned_channels == 0 || (r_raw_rc_flags & (PX4IO_P_RAW_RC_FLAGS_FAILSAFE))) {
 			rc_input_lost = true;
 		} else {
 			/* set RC OK flag */

src/modules/px4iofirmware/protocol.h

@@ -111,7 +111,6 @@
 #define PX4IO_P_STATUS_FLAGS_INIT_OK		(1 << 10) /* initialisation of the IO completed without error */
 #define PX4IO_P_STATUS_FLAGS_FAILSAFE		(1 << 11) /* failsafe is active */
 #define PX4IO_P_STATUS_FLAGS_SAFETY_OFF		(1 << 12) /* safety is off */
-#define PX4IO_P_STATUS_FLAGS_RC_DSM11		(1 << 13) /* DSM input is 11 bit data */
 
 #define PX4IO_P_STATUS_ALARMS			3	 /* alarm flags - alarms latch, write 1 to a bit to clear it */
 #define PX4IO_P_STATUS_ALARMS_VBATT_LOW		(1 << 0) /* [1] VBatt is very close to regulator dropout */
@@ -128,8 +127,6 @@
 #define PX4IO_P_STATUS_VSERVO			6	/* [2] servo rail voltage in mV */
 #define PX4IO_P_STATUS_VRSSI			7	/* [2] RSSI voltage */
 #define PX4IO_P_STATUS_PRSSI			8	/* [2] RSSI PWM value */
-#define PX4IO_P_STATUS_NRSSI			9	/* [2] Normalized RSSI value, 0: no reception, 255: perfect reception */
-#define PX4IO_P_STATUS_RC_DATA			10	/* [1] + [2] Details about the RC source (PPM frame length, Spektrum protocol type) */
 
 /* array of post-mix actuator outputs, -10000..10000 */
 #define PX4IO_PAGE_ACTUATORS		2		/* 0..CONFIG_ACTUATOR_COUNT-1 */
@@ -140,7 +137,16 @@
 /* array of raw RC input values, microseconds */
 #define PX4IO_PAGE_RAW_RC_INPUT		4
 #define PX4IO_P_RAW_RC_COUNT			0	/* number of valid channels */
-#define PX4IO_P_RAW_RC_BASE			1	/* CONFIG_RC_INPUT_COUNT channels from here */
+#define PX4IO_P_RAW_RC_FLAGS			1	/* RC detail status flags */
+#define PX4IO_P_RAW_RC_FLAGS_FRAME_DROP		(1 << 0) /* single frame drop */
+#define PX4IO_P_RAW_RC_FLAGS_FAILSAFE		(1 << 1) /* receiver is in failsafe mode */
+#define PX4IO_P_RAW_RC_FLAGS_RC_DSM11		(1 << 2) /* DSM decoding is 11 bit mode */
+
+#define PX4IO_P_RAW_RC_NRSSI			2	/* [2] Normalized RSSI value, 0: no reception, 255: perfect reception */
+#define PX4IO_P_RAW_RC_DATA			3	/* [1] + [2] Details about the RC source (PPM frame length, Spektrum protocol type) */
+#define PX4IO_P_RAW_FRAME_COUNT			4	/* Number of total received frames (wrapping counter) */
+#define PX4IO_P_RAW_LOST_FRAME_COUNT		5	/* Number of total dropped frames (wrapping counter) */
+#define PX4IO_P_RAW_RC_BASE			6	/* CONFIG_RC_INPUT_COUNT channels from here */
 
 /* array of scaled RC input values, -10000..10000 */
 #define PX4IO_PAGE_RC_INPUT		5

src/modules/px4iofirmware/px4io.h

@@ -96,6 +96,7 @@ extern uint16_t			r_page_servo_disarmed[];	/* PX4IO_PAGE_DISARMED_PWM */
 
 #define r_raw_rc_count		r_page_raw_rc_input[PX4IO_P_RAW_RC_COUNT]
 #define r_raw_rc_values		(&r_page_raw_rc_input[PX4IO_P_RAW_RC_BASE])
+#define r_raw_rc_flags		r_page_raw_rc_input[PX4IO_P_RAW_RC_FLAGS]
 #define r_rc_valid		r_page_rc_input[PX4IO_P_RC_VALID]
 #define r_rc_values		(&r_page_rc_input[PX4IO_P_RC_BASE])
 
@@ -215,7 +216,7 @@ extern int	dsm_init(const char *device);
 extern bool	dsm_input(uint16_t *values, uint16_t *num_values);
 extern void	dsm_bind(uint16_t cmd, int pulses);
 extern int	sbus_init(const char *device);
-extern bool	sbus_input(uint16_t *values, uint16_t *num_values, uint16_t *rssi, uint16_t max_channels);
+extern bool	sbus_input(uint16_t *values, uint16_t *num_values, bool *sbus_failsafe, bool *sbus_frame_drop, uint16_t max_channels);
 
 /** global debug level for isr_debug() */
 extern volatile uint8_t debug_level;

src/modules/px4iofirmware/registers.c

@@ -90,8 +90,6 @@ uint16_t		r_page_status[] = {
 	[PX4IO_P_STATUS_VSERVO]			= 0,
 	[PX4IO_P_STATUS_VRSSI]			= 0,
 	[PX4IO_P_STATUS_PRSSI]			= 0,
-	[PX4IO_P_STATUS_NRSSI]			= 0,
-	[PX4IO_P_STATUS_RC_DATA]		= 0
 };
 
 /**
@@ -116,6 +114,12 @@ uint16_t		r_page_servos[PX4IO_SERVO_COUNT];
 uint16_t		r_page_raw_rc_input[] =
 {
 	[PX4IO_P_RAW_RC_COUNT]			= 0,
+	[PX4IO_P_RAW_RC_FLAGS]			= 0,
+	[PX4IO_P_RAW_RC_NRSSI]			= 0,
+	[PX4IO_P_RAW_RC_DATA]			= 0,
+	[PX4IO_P_RAW_FRAME_COUNT]		= 0,
+	[PX4IO_P_RAW_LOST_FRAME_COUNT]		= 0,
+	[PX4IO_P_RAW_RC_DATA]			= 0,
 	[PX4IO_P_RAW_RC_BASE ... (PX4IO_P_RAW_RC_BASE + PX4IO_RC_INPUT_CHANNELS)] = 0
 };
 

src/modules/px4iofirmware/sbus.c

@@ -87,7 +87,7 @@ static unsigned partial_frame_count;
 
 unsigned sbus_frame_drops;
 
-static bool sbus_decode(hrt_abstime frame_time, uint16_t *values, uint16_t *num_values, uint16_t *rssi, uint16_t max_channels);
+static bool sbus_decode(hrt_abstime frame_time, uint16_t *values, uint16_t *num_values, bool *sbus_failsafe, bool *sbus_frame_drop, uint16_t max_channels);
 
 int
 sbus_init(const char *device)
@@ -118,7 +118,7 @@ sbus_init(const char *device)
 }
 
 bool
-sbus_input(uint16_t *values, uint16_t *num_values, uint16_t *rssi, uint16_t max_channels)
+sbus_input(uint16_t *values, uint16_t *num_values, bool *sbus_failsafe, bool *sbus_frame_drop, uint16_t max_channels)
 {
 	ssize_t		ret;
 	hrt_abstime	now;
@@ -175,7 +175,7 @@ sbus_input(uint16_t *values, uint16_t *num_values, uint16_t *rssi, uint16_t max_
 	 * decode it.
 	 */
 	partial_frame_count = 0;
-	return sbus_decode(now, values, num_values, rssi, max_channels);
+	return sbus_decode(now, values, num_values, sbus_failsafe, sbus_frame_drop, max_channels);
 }
 
 /*
@@ -215,7 +215,7 @@ static const struct sbus_bit_pick sbus_decoder[SBUS_INPUT_CHANNELS][3] = {
 };
 
 static bool
-sbus_decode(hrt_abstime frame_time, uint16_t *values, uint16_t *num_values, uint16_t *rssi, uint16_t max_values)
+sbus_decode(hrt_abstime frame_time, uint16_t *values, uint16_t *num_values, bool *sbus_failsafe, bool *sbus_frame_drop, uint16_t max_values)
 {
 	/* check frame boundary markers to avoid out-of-sync cases */
 	if ((frame[0] != 0x0f)) {
@@ -289,20 +289,23 @@ sbus_decode(hrt_abstime frame_time, uint16_t *values, uint16_t *num_values, uint
 	/* decode and handle failsafe and frame-lost flags */
 	if (frame[SBUS_FLAGS_BYTE] & (1 << SBUS_FAILSAFE_BIT)) { /* failsafe */
 		/* report that we failed to read anything valid off the receiver */
-		*rssi = 0;
+		*sbus_failsafe = true;
+		*sbus_frame_drop = true;
 		return false;
 	}
 	else if (frame[SBUS_FLAGS_BYTE] & (1 << SBUS_FRAMELOST_BIT)) { /* a frame was lost */
-		/* set a special warning flag or try to calculate some kind of RSSI information - to be implemented 
+		/* set a special warning flag
 		 * 
 		 * Attention! This flag indicates a skipped frame only, not a total link loss! Handling this 
 		 * condition as fail-safe greatly reduces the reliability and range of the radio link, 
 		 * e.g. by prematurely issueing return-to-launch!!! */
 
-		*rssi = 100; // XXX magic number indicating bad signal, but not a signal loss (yet)
+		*sbus_failsafe = false;
+		*sbus_frame_drop = true;
+	} else {
+		*sbus_failsafe = false;
+		*sbus_frame_drop = false;
 	}
 
-	*rssi = 255;
-
 	return true;
 }