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AP_RCProtocol: switched SRXL to SoftSerial decoder

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This commit is contained in:
Andrew Tridgell 2018-11-05 13:02:22 +11:00
parent 87cf160875
commit b93dee7fe6
2 changed files with 7 additions and 65 deletions
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65
libraries/AP_RCProtocol/AP_RCProtocol_SRXL.cpp
View File

@ -49,69 +49,12 @@ uint16_t AP_RCProtocol_SRXL::srxl_crc16(uint16_t crc, uint8_t new_byte)
void AP_RCProtocol_SRXL::process_pulse(uint32_t width_s0, uint32_t width_s1)
{
// convert to bit widths, allowing for up to about 4usec error, assuming 115200 bps
uint16_t bits_s0 = ((width_s0+4)*(uint32_t)115200) / 1000000;
uint16_t bits_s1 = ((width_s1+4)*(uint32_t)115200) / 1000000;
uint8_t bit_ofs, byte_ofs;
uint16_t nbits;
uint8_t b;
if (ss.process_pulse(width_s0, width_s1, b)) {
_process_byte(clock_us, b, 115200);
}
// keep a clock based on the pulses
clock_us += (width_s0 + width_s1);
if (bits_s0 == 0 || bits_s1 == 0) {
// invalid data
goto reset;
}
byte_ofs = srxl_state.bit_ofs/10;
bit_ofs = srxl_state.bit_ofs%10;
if (byte_ofs >= SRXL_FRAMELEN_MAX) {
goto reset;
}
// pull in the high bits
nbits = bits_s0;
if (nbits+bit_ofs > 10) {
nbits = 10 - bit_ofs;
}
srxl_state.bytes[byte_ofs] |= ((1U<<nbits)-1) << bit_ofs;
srxl_state.bit_ofs += nbits;
bit_ofs += nbits;
if (bits_s0 - nbits > 10) {
// we have a full frame
uint8_t byte;
uint8_t i;
for (i=0; i <= byte_ofs; i++) {
// get raw data
uint16_t v = srxl_state.bytes[i];
// check start bit
if ((v & 1) != 0) {
break;
}
// check stop bits
if ((v & 0x200) != 0x200) {
break;
}
byte = ((v>>1) & 0xFF);
_process_byte(clock_us, byte, 115200);
}
memset(&srxl_state, 0, sizeof(srxl_state));
}
byte_ofs = srxl_state.bit_ofs/10;
bit_ofs = srxl_state.bit_ofs%10;
if (bits_s1+bit_ofs > 10) {
// invalid data
goto reset;
}
// pull in the low bits
srxl_state.bit_ofs += bits_s1;
return;
reset:
memset(&srxl_state, 0, sizeof(srxl_state));
}

7
libraries/AP_RCProtocol/AP_RCProtocol_SRXL.h
View File

@ -18,6 +18,7 @@
#pragma once
#include "AP_RCProtocol.h"
#include "SoftSerial.h"
#define SRXL_MIN_FRAMESPACE_US 8000U /* Minumum space between srxl frames in us (applies to all variants) */
#define SRXL_MAX_CHANNELS 20U /* Maximum number of channels from srxl datastream */
@ -62,8 +63,6 @@ private:
uint16_t crc_fmu = 0U; /* CRC calculated over payload from srxl datastream on this machine */
uint16_t crc_receiver = 0U; /* CRC extracted from srxl datastream */
uint32_t clock_us; /* clock calculated from pulse lengths */
struct {
uint16_t bytes[SRXL_FRAMELEN_MAX];
uint16_t bit_ofs;
} srxl_state;
SoftSerial ss{115200, SoftSerial::SERIAL_CONFIG_8N1};
};