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AP_HAL: support up to 20 channels on SRXL

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tested with 18 channels on a DSM18 transmitter with a AR7700 receiver
with SRXL port
This commit is contained in:
Andrew Tridgell 2016-10-15 16:26:13 +11:00
parent ece0a8721f
commit ec8c22f26e
2 changed files with 23 additions and 6 deletions
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27
libraries/AP_HAL/utility/srxl.cpp
View File

@ -26,7 +26,7 @@
/*
there are other SRXL varients, but we need some sample data before accepting them
*/
#define SRXL_MAX_CHANNELS 16
#define SRXL_MAX_CHANNELS 20
#define SRXL_HEAD_MARKER 0xA5
#define SRXL_NUM_BYTES 18
@ -58,7 +58,7 @@ static uint16_t srxl_crc16(const uint8_t *bytes, uint8_t nbytes)
/*
decode a SRXL packet
*/
int srxl_decode(uint64_t timestamp_us, uint8_t byte, uint8_t *num_values, uint16_t *values, uint16_t max_values)
int srxl_decode(uint64_t timestamp_us, uint8_t byte, uint8_t *num_values, uint16_t *values, uint16_t max_values, bool *failsafe_state)
{
if (timestamp_us - last_data_us > 5000U || buflen == SRXL_NUM_BYTES) {
// we've seen a frame gap
@ -98,10 +98,21 @@ int srxl_decode(uint64_t timestamp_us, uint8_t byte, uint8_t *num_values, uint16
uint16_t b = buffer[i*2+2] << 8 | buffer[i*2+3];
uint16_t c = b >> 11; // channel number
int32_t v = b & 0x7FF;
if (b & 0x8000) {
//printf("bad data 0x%04x\n", b);
// bad data
return 2;
}
if (c == 12) {
// special handling for channel 12
// see http://www.deviationtx.com/forum/protocol-development/2088-18-channels-for-dsm2-dsmx?start=40
//printf("c12: 0x%x %02x %02x\n", (unsigned)(b>>9), (unsigned)buffer[0], (unsigned)buffer[1]);
v = (b & 0x1FF) * 4;
c = 12 + (((b >> 9) & 0x3) | ((buffer[1]&1)<<2));
}
// if channel number if greater than 16 then it is a X-Plus
// channel. We don't yet know how to decode those. There is some information here:
// http://www.deviationtx.com/forum/protocol-development/2088-18-channels-for-dsm2-dsmx?start=40
// but we really need some sample data to confirm
if (c < SRXL_MAX_CHANNELS) {
v = (((v - 0x400) * 500) / 876) + 1500;
@ -110,6 +121,7 @@ int srxl_decode(uint64_t timestamp_us, uint8_t byte, uint8_t *num_values, uint16
max_channels = c+1;
}
}
//printf("%u:%u ", (unsigned)c, (unsigned)v);
}
//printf("\n");
@ -120,6 +132,10 @@ int srxl_decode(uint64_t timestamp_us, uint8_t byte, uint8_t *num_values, uint16
}
memcpy(values, channels, (*num_values)*2);
// check failsafe bit, this goes low when connection to the
// transmitter is lost
*failsafe_state = ((buffer[1] & 2) == 0);
#if 0
for (uint8_t i=0; i<buflen; i++) {
printf("%02x ", (unsigned)buffer[i]);
@ -185,6 +201,7 @@ int main(int argc, const char *argv[])
uint8_t b;
uint8_t num_values = 0;
uint16_t values[18];
bool failsafe_state;
fd_set fds;
struct timeval tv;
@ -203,13 +220,13 @@ int main(int argc, const char *argv[])
break;
}
if (srxl_decode(micros64(), b, &num_values, values, 18) == 0) {
if (srxl_decode(micros64(), b, &num_values, values, 18, &failsafe_state) == 0) {
#if 1
printf("%u: ", num_values);
for (uint8_t i=0; i<num_values; i++) {
printf("%u:%4u ", i+1, values[i]);
}
printf("\n");
printf("%s\n", failsafe_state?"FAIL":"OK");
#endif
}
}

2
libraries/AP_HAL/utility/srxl.h
View File

@ -25,4 +25,4 @@
*
* @return 0 for success (a decoded packet), 1 for no packet yet (accumulating), 2 for unknown packet, 4 for checksum error
*/
int srxl_decode(uint64_t timestamp_us, uint8_t byte, uint8_t *num_values, uint16_t *values, uint16_t max_values);
int srxl_decode(uint64_t timestamp_us, uint8_t byte, uint8_t *num_values, uint16_t *values, uint16_t max_values, bool *failsafe_state);