--- /dev/null
+#include "rtl_433.h"
+#include "pulse_demod.h"
+#include "util.h"
+
+// Transmitter speed in bits per seconds
+#define RH_ASK_SPEED 2000
+#define RH_ASK_BIT_LEN (int)1e6/RH_ASK_SPEED
+
+// Maximum message length (including the headers, byte count and FCS) we are willing to support
+// This is pretty arbitrary
+#define RH_ASK_MAX_PAYLOAD_LEN 67
+#define RH_ASK_HEADER_LEN 4
+#ifndef RH_ASK_MAX_MESSAGE_LEN
+ #define RH_ASK_MAX_MESSAGE_LEN (RH_ASK_MAX_PAYLOAD_LEN - RH_ASK_HEADER_LEN - 3)
+#endif
+
+uint8_t payload[RH_ASK_MAX_PAYLOAD_LEN] = {0};
+int data_payload[RH_ASK_MAX_MESSAGE_LEN];
+
+// Note: all tje "4to6 code" came from RadioHead source code.
+// see: http://www.airspayce.com/mikem/arduino/RadioHead/index.html
+
+// 4 bit to 6 bit symbol converter table
+// Used to convert the high and low nybbles of the transmitted data
+// into 6 bit symbols for transmission. Each 6-bit symbol has 3 1s and 3 0s
+// with at most 3 consecutive identical bits
+static uint8_t symbols[] = {
+ 0xd, 0xe, 0x13, 0x15, 0x16, 0x19, 0x1a, 0x1c,
+ 0x23, 0x25, 0x26, 0x29, 0x2a, 0x2c, 0x32, 0x34
+};
+
+// Convert a 6 bit encoded symbol into its 4 bit decoded equivalent
+uint8_t symbol_6to4(uint8_t symbol)
+{
+ uint8_t i;
+ // Linear search :-( Could have a 64 byte reverse lookup table?
+ // There is a little speedup here courtesy Ralph Doncaster:
+ // The shortcut works because bit 5 of the symbol is 1 for the last 8
+ // symbols, and it is 0 for the first 8.
+ // So we only have to search half the table
+ for (i = (symbol>>2) & 8; i < 16 ; i++){
+ if (symbol == symbols[i]) return i;
+ }
+ return 0xFF; // Not found
+}
+
+
+static int radiohead_ask_callback(bitbuffer_t *bitbuffer) {
+ // Get time
+ char time_str[LOCAL_TIME_BUFLEN];
+ data_t *data;
+ local_time_str(0, time_str);
+
+ uint8_t row = 0; // we are considering only first row
+ unsigned int len = bitbuffer->bits_per_row[row];
+
+ uint8_t msg_len = RH_ASK_MAX_MESSAGE_LEN;
+ unsigned int pos, nb_bytes;
+ uint8_t rxBits[2] = {0};
+
+ uint16_t crc, crc_recompute;
+ uint8_t data_len, header_to, header_from, header_id, header_flags;
+
+
+ // Looking for preamble
+ uint8_t init_pattern[] = {
+ 0x55, // 8
+ 0x55, // 16
+ 0x55, // 24
+ 0x51, // 32
+ 0xcd, // 40
+ };
+ // The first 0 is ignored by the decoder, so we look only for 28 bits of "01"
+ // and not 32. Also "0x1CD" is 0xb38 (RH_ASK_START_SYMBOL) with LSBit first.
+ uint8_t init_pattern_len = 40;
+
+ pos = bitbuffer_search(bitbuffer, row, 0, init_pattern, init_pattern_len);
+ if(pos == len){
+ if(debug_output) {
+ printf("RH ASK preamble not found\n");
+ }
+ return 0;
+ }
+
+ // read "bytes" of 12 bit
+ nb_bytes=0;
+ pos += init_pattern_len;
+ for(; pos < len && nb_bytes < msg_len; pos += 12){
+ bitbuffer_extract_bytes(bitbuffer, row, pos, rxBits, /*len=*/16);
+ // ^ we should read 16 bits and not 12, elsewhere last 4bits are ignored
+ rxBits[0] = reverse8(rxBits[0]);
+ rxBits[1] = reverse8(rxBits[1]);
+ rxBits[1] = ((rxBits[1] & 0x0F)<<2) + (rxBits[0]>>6);
+ rxBits[0] &= 0x3F;
+ uint8_t hi_nibble = symbol_6to4(rxBits[0]);
+ if(hi_nibble > 0xF){
+ if(debug_output){
+ fprintf(stdout, "Error on 6to4 decoding high nibble: %X\n", rxBits[0]);
+ }
+ return 0;
+ }
+ uint8_t lo_nibble = symbol_6to4(rxBits[1]);
+ if(lo_nibble > 0xF){
+ if(debug_output){
+ fprintf(stdout, "Error on 6to4 decoding low nibble: %X\n", rxBits[1]);
+ }
+ return 0;
+ }
+ uint8_t byte = hi_nibble<<4 | lo_nibble;
+ payload[nb_bytes] = byte;
+ if(nb_bytes == 0){
+ msg_len = byte;
+ }
+ nb_bytes++;
+ }
+
+ // Get header
+ data_len = msg_len - RH_ASK_HEADER_LEN - 3;
+ header_to = payload[1];
+ header_from = payload[2];
+ header_id = payload[3];
+ header_flags = payload[4];
+
+ // Check CRC
+ crc = payload[5 + data_len] + (payload[5 + data_len + 1]<<8);
+ crc_recompute = ~crc16(payload, msg_len-2, 0x8408, 0xFFFF);
+ if(crc_recompute != crc){
+ if(debug_output){
+ fprintf(stdout, "CRC error: %04X != %04X\n", crc_recompute, crc);
+ }
+ return 0;
+ }
+
+ // Format data
+ for(int j=0; j<msg_len; j++){
+ data_payload[j] = (int)payload[5+j];
+ }
+ data = data_make("time", "", DATA_STRING, time_str,
+ "model", "", DATA_STRING, "RadioHead ASK",
+ "crc", "", DATA_STRING, "OK",
+ "len", "Data len", DATA_INT, data_len,
+ "to", "To", DATA_INT, header_to,
+ "from", "From", DATA_INT, header_from,
+ "id", "Id", DATA_INT, header_id,
+ "flags", "Flags", DATA_INT, header_flags,
+ "payload", "Payload", DATA_ARRAY, data_array(data_len, DATA_INT, data_payload),
+ NULL);
+ data_acquired_handler(data);
+
+ return 0;
+}
+
+static char *output_fields[] = {
+ "time",
+ "model",
+ "crc",
+ "len",
+ "to",
+ "from",
+ "id",
+ "flags",
+ "payload",
+ NULL
+};
+
+r_device radiohead_ask = {
+ .name = "Radiohead ASK",
+ .modulation = OOK_PULSE_PCM_RZ,
+ .short_limit = RH_ASK_BIT_LEN,
+ .long_limit = RH_ASK_BIT_LEN,
+ .reset_limit = RH_ASK_BIT_LEN*10,
+ .json_callback = &radiohead_ask_callback,
+ .fields = output_fields,
+};
projects / rtl-433.git / blobdiff