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S.BUS: Expose frame drop variable

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Lorenz Meier
2015-12-03 17:20:11 +01:00
parent 976d541940
commit e41fa79b81
2 changed files with 27 additions and 4 deletions
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src/lib/rc/sbus.c
+22 -4
View File
@@ -53,6 +53,8 @@
#define SBUS_FRAMELOST_BIT 2
#define SBUS1_FRAME_DELAY 14000
#define SBUS_SINGLE_CHAR_LEN_US ((1/((100000/10)) * 1000 * 1000)
/*
Measured values with Futaba FX-30/R6108SB:
-+100% on TX: PCM 1.100/1.520/1.950ms -> SBus raw values: 350/1024/1700 (100% ATV)
@@ -81,6 +83,12 @@ static unsigned partial_frame_count;
unsigned sbus_frame_drops;
unsigned
sbus_dropped_frames()
{
return sbus_frame_drops;
}
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);
@@ -108,7 +116,7 @@ sbus_init(const char *device, bool singlewire)
/* initialise the decoder */
partial_frame_count = 0;
last_rx_time = hrt_absolute_time();
sbus_frame_drops = 0;
}
return sbus_fd;
@@ -172,9 +180,9 @@ sbus_input(int sbus_fd, uint16_t *values, uint16_t *num_values, bool *sbus_fails
* so we detect frame boundaries by the inter-frame delay.
*
* The minimum frame spacing is 7ms; with 25 bytes at 100000bps
* frame transmission time is ~2ms.
* frame transmission time is ~2500 us.
*
* If an interval of more than 4ms passes between calls,
* If an interval of more than 2ms passes between calls,
* the first byte we read will be the first byte of a frame.
*
* In the case where byte(s) are dropped from a frame, this also
@@ -183,6 +191,9 @@ sbus_input(int sbus_fd, uint16_t *values, uint16_t *num_values, bool *sbus_fails
*/
now = hrt_absolute_time();
/*
* If we timed out, reset the decoder
*/
if ((now - last_rx_time) > 4000) {
if (partial_frame_count > 0) {
sbus_frame_drops++;
@@ -201,6 +212,13 @@ sbus_input(int sbus_fd, uint16_t *values, uint16_t *num_values, bool *sbus_fails
return false;
}
/* if the first byte of the frame is not the start symbol, give up instantly */
if (frame[0] != SBUS_START_SYMBOL) {
sbus_frame_drops++;
partial_frame_count = 0;
return false;
}
last_rx_time = now;
/*
@@ -264,7 +282,7 @@ sbus_decode(hrt_abstime frame_time, uint16_t *values, uint16_t *num_values, bool
uint16_t max_values)
{
/* check frame boundary markers to avoid out-of-sync cases */
if ((frame[0] != 0x0f)) {
if ((frame[0] != SBUS_START_SYMBOL)) {
sbus_frame_drops++;
return false;
}
src/lib/rc/sbus.h
+5
View File
@@ -71,4 +71,9 @@ __EXPORT bool sbus_input(int sbus_fd, uint16_t *values, uint16_t *num_values, bo
__EXPORT void sbus1_output(int sbus_fd, uint16_t *values, uint16_t num_values);
__EXPORT void sbus2_output(int sbus_fd, uint16_t *values, uint16_t num_values);
/**
* The number of incomplete frames we encountered
*/
__EXPORT unsigned sbus_dropped_frames(void);
__END_DECLS