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/*
* @file sumd.h
*
* RC protocol definition for Graupner HoTT transmitter
*
* @author Marco Bauer <marco@wtns.de>
*/
#include <stdbool.h>
#include <stdio.h>
#include "sumd.h"
enum SUMD_DECODE_STATE {
SUMD_DECODE_STATE_UNSYNCED = 0,
SUMD_DECODE_STATE_GOT_HEADER,
SUMD_DECODE_STATE_GOT_STATE,
SUMD_DECODE_STATE_GOT_LEN,
SUMD_DECODE_STATE_GOT_DATA,
SUMD_DECODE_STATE_GOT_CRC,
SUMD_DECODE_STATE_GOT_CRC16_BYTE_1,
SUMD_DECODE_STATE_GOT_CRC16_BYTE_2
};
/*
const char *decode_states[] = {"UNSYNCED",
"GOT_HEADER",
"GOT_STATE",
"GOT_LEN",
"GOT_DATA",
"GOT_CRC",
"GOT_CRC16_BYTE_1",
"GOT_CRC16_BYTE_2"
};
*/
uint8_t _crc8 = 0x00;
uint16_t _crc16 = 0x0000;
bool _sumd = true;
bool _crcOK = false;
bool _debug = false;
/* define range mapping here, -+100% -> 1000..2000 */
#define SUMD_RANGE_MIN 0.0f
#define SUMD_RANGE_MAX 4096.0f
#define SUMD_TARGET_MIN 1000.0f
#define SUMD_TARGET_MAX 2000.0f
/* pre-calculate the floating point stuff as far as possible at compile time */
#define SUMD_SCALE_FACTOR ((SUMD_TARGET_MAX - SUMD_TARGET_MIN) / (SUMD_RANGE_MAX - SUMD_RANGE_MIN))
#define SUMD_SCALE_OFFSET (int)(SUMD_TARGET_MIN - (SUMD_SCALE_FACTOR * SUMD_RANGE_MIN + 0.5f))
static enum SUMD_DECODE_STATE _decode_state = SUMD_DECODE_STATE_UNSYNCED;
static uint8_t _rxlen;
static ReceiverFcPacketHoTT _rxpacket;
uint16_t sumd_crc16(uint16_t crc, uint8_t value)
{
int i;
crc ^= (uint16_t)value << 8;
for (i = 0; i < 8; i++) {
crc = (crc & 0x8000) ? (crc << 1) ^ 0x1021 : (crc << 1);
}
return crc;
}
uint8_t sumd_crc8(uint8_t crc, uint8_t value)
{
crc += value;
return crc;
}
int sumd_decode(uint8_t byte, uint8_t *rssi, uint8_t *rx_count, uint16_t *channel_count, uint16_t *channels,
uint16_t max_chan_count)
{
int ret = 1;
switch (_decode_state) {
case SUMD_DECODE_STATE_UNSYNCED:
if(_debug)
printf( " SUMD_DECODE_STATE_UNSYNCED \n") ;
if (byte == SUMD_HEADER_ID) {
_rxpacket.header = byte;
_sumd = true;
_rxlen = 0;
_crc16 = 0x0000;
_crc8 = 0x00;
_crcOK = false;
_crc16 = sumd_crc16(_crc16, byte);
_crc8 = sumd_crc8(_crc8, byte);
_decode_state = SUMD_DECODE_STATE_GOT_HEADER;
if(_debug)
printf( " SUMD_DECODE_STATE_GOT_HEADER: %x \n", byte) ;
} else {
ret = 3;
}
break;
case SUMD_DECODE_STATE_GOT_HEADER:
if (byte == SUMD_ID_SUMD || byte == SUMD_ID_SUMH) {
_rxpacket.status = byte;
if (byte == SUMD_ID_SUMH) {
_sumd = false;
}
if (_sumd) {
_crc16 = sumd_crc16(_crc16, byte);
} else {
_crc8 = sumd_crc8(_crc8, byte);
}
_decode_state = SUMD_DECODE_STATE_GOT_STATE;
if(_debug)
printf( " SUMD_DECODE_STATE_GOT_STATE: %x \n", byte) ;
} else {
_decode_state = SUMD_DECODE_STATE_UNSYNCED;
}
break;
case SUMD_DECODE_STATE_GOT_STATE:
if (byte >= 2 && byte <= SUMD_MAX_CHANNELS) {
_rxpacket.length = byte;
if (_sumd) {
_crc16 = sumd_crc16(_crc16, byte);
} else {
_crc8 = sumd_crc8(_crc8, byte);
}
_rxlen++;
_decode_state = SUMD_DECODE_STATE_GOT_LEN;
if(_debug)
printf( " SUMD_DECODE_STATE_GOT_LEN: %x (%d) \n", byte, byte) ;
} else {
_decode_state = SUMD_DECODE_STATE_UNSYNCED;
}
break;
case SUMD_DECODE_STATE_GOT_LEN:
_rxpacket.sumd_data[_rxlen] = byte;
if (_sumd) {
_crc16 = sumd_crc16(_crc16, byte);
} else {
_crc8 = sumd_crc8(_crc8, byte);
}
_rxlen++;
if (_rxlen <= ((_rxpacket.length*2) )) {
if(_debug)
printf( " SUMD_DECODE_STATE_GOT_DATA[%d]: %x\n", _rxlen-2, byte) ;
} else {
_decode_state = SUMD_DECODE_STATE_GOT_DATA;
if(_debug)
printf( " SUMD_DECODE_STATE_GOT_DATA -- finish --\n") ;
}
break;
case SUMD_DECODE_STATE_GOT_DATA:
_rxpacket.crc16_high = byte;
if(_debug)
printf( " SUMD_DECODE_STATE_GOT_CRC16[1]: %x [%x]\n", byte, ((_crc16 >> 8) & 0xff)) ;
if (_sumd) {
_decode_state = SUMD_DECODE_STATE_GOT_CRC;
} else {
_decode_state = SUMD_DECODE_STATE_GOT_CRC16_BYTE_1;
}
break;
case SUMD_DECODE_STATE_GOT_CRC16_BYTE_1:
_rxpacket.crc16_low = byte;
if(_debug)
printf( " SUMD_DECODE_STATE_GOT_CRC16[2]: %x [%x]\n", byte, (_crc16 & 0xff)) ;
_decode_state = SUMD_DECODE_STATE_GOT_CRC16_BYTE_2;
break;
case SUMD_DECODE_STATE_GOT_CRC16_BYTE_2:
_rxpacket.telemetry = byte;
if(_debug)
printf( " SUMD_DECODE_STATE_GOT_SUMH_TELEMETRY: %x\n", byte) ;
_decode_state = SUMD_DECODE_STATE_GOT_CRC;
break;
case SUMD_DECODE_STATE_GOT_CRC:
if (_sumd) {
_rxpacket.crc16_low = byte;
if(_debug)
printf( " SUMD_DECODE_STATE_GOT_CRC[2]: %x [%x]\n\n", byte, (_crc16 & 0xff)) ;
if (_crc16 == (uint16_t)(_rxpacket.crc16_high<<8)+_rxpacket.crc16_low) {
_crcOK = true;
}
} else {
_rxpacket.crc8 = byte;
if(_debug)
printf( " SUMD_DECODE_STATE_GOT_CRC8_SUMH: %x [%x]\n\n", byte, _crc8) ;
if (_crc8 == _rxpacket.crc8) {
_crcOK = true;
}
}
if (_crcOK) {
if(_debug)
printf( " CRC - OK \n") ;
if (_sumd) {
if(_debug)
printf( " Got valid SUMD Packet\n") ;
} else {
if(_debug)
printf( " Got valid SUMH Packet\n") ;
}
if(_debug)
printf( " RXLEN: %d [Chans: %d] \n\n", _rxlen-1, (_rxlen-1)/2) ;
ret = 0;
unsigned i;
uint8_t _cnt = *rx_count + 1;
*rx_count = _cnt;
*rssi = 255;
/* received Channels */
if ((uint16_t)_rxpacket.length > max_chan_count) {
_rxpacket.length = (uint8_t) max_chan_count;
}
*channel_count = (uint16_t)_rxpacket.length;
/* decode the actual packet */
/* reorder first 4 channels */
/* ch1 = roll -> sumd = ch2 */
channels[0] = (uint16_t)((_rxpacket.sumd_data[1*2+1]<<8) | _rxpacket.sumd_data[1*2+2])>>3;
/* ch2 = pitch -> sumd = ch2 */
channels[1] = (uint16_t)((_rxpacket.sumd_data[2*2+1]<<8) | _rxpacket.sumd_data[2*2+2])>>3;
/* ch3 = throttle -> sumd = ch2 */
channels[2] = (uint16_t)((_rxpacket.sumd_data[0*2+1]<<8) | _rxpacket.sumd_data[0*2+2])>>3;
/* ch4 = yaw -> sumd = ch2 */
channels[3] = (uint16_t)((_rxpacket.sumd_data[3*2+1]<<8) | _rxpacket.sumd_data[3*2+2])>>3;
/* we start at channel 5(index 4) */
unsigned chan_index = 4;
for (i = 4; i < _rxpacket.length; i++) {
if(_debug)
printf( "ch[%d] : %x %x [ %x %d ]\n", i+1, _rxpacket.sumd_data[i*2+1], _rxpacket.sumd_data[i*2+2], ((_rxpacket.sumd_data[i*2+1]<<8) | _rxpacket.sumd_data[i*2+2])>>3, ((_rxpacket.sumd_data[i*2+1]<<8) | _rxpacket.sumd_data[i*2+2])>>3);
channels[chan_index] = (uint16_t)((_rxpacket.sumd_data[i*2+1]<<8) | _rxpacket.sumd_data[i*2+2])>>3;
/* convert values to 1000-2000 ppm encoding in a not too sloppy fashion */
//channels[chan_index] = (uint16_t)(channels[chan_index] * SUMD_SCALE_FACTOR + .5f) + SUMD_SCALE_OFFSET;
chan_index++;
}
} else {
/* decoding failed */
ret = 4;
if(_debug)
printf( " CRC - fail \n") ;
}
_decode_state = SUMD_DECODE_STATE_UNSYNCED;
break;
}
return ret;
}
