+/* LaCrosse Color Forecast Station (model C85845), or other LaCrosse product
+ * utilizing the remote temperature/humidity sensor TX141TH-Bv2 transmitting
+ * in the 433.92 MHz band. Product pages:
+ * http://www.lacrossetechnology.com/c85845-color-weather-station/
+ * http://www.lacrossetechnology.com/tx141th-bv2-temperature-humidity-sensor
+ *
+ * The TX141TH-Bv2 protocol is OOK modulated PWM with fixed period of 625 us
+ * for data bits, preambled by four long startbit pulses of fixed period equal
+ * to ~1666 us. Hence, it is similar to Bresser Thermo-/Hygro-Sensor 3CH (bresser_3ch.c
+ * included in this source code) with the exception that OOK_PULSE_PWM_TERNARY
+ * modulation type is technically more correct than OOK_PULSE_PWM_RAW.
+ *
+ * A single data packet looks as follows:
+ * 1) preamble - 833 us high followed by 833 us low, repeated 4 times:
+ * ---- ---- ---- ----
+ * | | | | | | | |
+ * ---- ---- ---- ----
+ * 2) a train of 40 data pulses with fixed 625 us period follows immediately:
+ * --- -- -- --- --- -- ---
+ * | | | | | | | | | | | | | |
+ * -- --- --- -- -- --- -- ....
+ * A logical 1 is 417 us of high followed by 208 us of low.
+ * A logical 0 is 208 us of high followed by 417 us of low.
+ * Thus, in the pictorial example above the bits are 1 0 0 1 1 0 1 ....
+ *
+ * The TX141TH-Bv2 sensor sends 12 of identical packets, one immediately following
+ * the other, in a single burst. These 12-packet bursts repeat every 50 seconds. At
+ * the end of the last packet there are two 833 us pulses ("post-amble"?).
+ *
+ * The data is grouped in 5 bytes / 10 nybbles
+ * [id] [id] [flags] [temp] [temp] [temp] [humi] [humi] [chk] [chk]
+ *
+ * The "id" is an 8 bit random integer generated when the sensor powers up for the
+ * first time; "flags" are 4 bits for battery low indicator, test button press,
+ * and channel; "temp" is 12 bit unsigned integer which encodes temperature in degrees
+ * Celsius as follows:
+ * temp_c = temp/10 - 50
+ * to account for the -40 C -- 60 C range; "humi" is 8 bit integer indicating
+ * relative humidity in %. The method of calculating "chk", the presumed 8-bit checksum
+ * remains a complete mystery at the moment of this writing, and I am not totally sure
+ * if the last is any kind of CRC. I've run reveng 1.4.4 on exemplary data with all
+ * available CRC algorithms and found no match. Be my guest if you want to
+ * solve it - for example, if you figure out why the following two pairs have identical
+ * checksums you'll become a hero:
+ *
+ * 0x87 0x02 0x3c 0x3b 0xe1
+ * 0x87 0x02 0x7d 0x37 0xe1
+ *
+ * 0x87 0x01 0xc3 0x31 0xd8
+ * 0x87 0x02 0x28 0x37 0xd8
+ *
+ * Developer's comment 1: because of our choice of the OOK_PULSE_PWM_TERNARY type, the input
+ * array of bits will look like this:
+ * bitbuffer:: Number of rows: 25
+ * [00] {0} :
+ * [01] {0} :
+ * [02] {0} :
+ * [03] {0} :
+ * [04] {40} 87 02 67 39 f6
+ * [05] {0} :
+ * [06] {0} :
+ * [07] {0} :
+ * [08] {40} 87 02 67 39 f6
+ * [09] {0} :
+ * [10] {0} :
+ * [11] {0} :
+ * [12] {40} 87 02 67 39 f6
+ * [13] {0} :
+ * [14] {0} :
+ * [15] {0} :
+ * [16] {40} 87 02 67 39 f6
+ * [17] {0} :
+ * [18] {0} :
+ * [19] {0} :
+ * [20] {40} 87 02 67 39 f6
+ * [21] {0} :
+ * [22] {0} :
+ * [23] {0} :
+ * [24] {280} 87 02 67 39 f6 87 02 67 39 f6 87 02 67 39 f6 87 02 67 39 f6 87 02 67 39 f6 87 02 67 39 f6 87 02 67 39 f6
+ * which is a direct consequence of two factors: (1) pulse_demod_pwm_ternary() always assuming
+ * only one startbit, and (2) bitbuffer_add_row() not adding rows beyond BITBUF_ROWS. This is
+ * OK because the data is clearly processable and the unique pattern minimizes the chance of
+ * confusion with other sensors, particularly Bresser 3CH.
+ *
+ * Developer's comment 2: with unknown CRC (see above) the obvious way of checking the data
+ * integrity is making use of the 12 packet repetition. In principle, transmission errors are
+ * be relatively rare, thus the most frequent packet (statistical mode) should represent
+ * the true data. Therefore, in the fisrt part of the callback routine the mode is determined
+ * for the first 4 bytes of the data compressed into a single 32-bit integer. Since the packet
+ * count is small, no sophisticated mode algorithm is necessary; a simple array of <data,count>
+ * structures is sufficient. The added bonus is that relative count enables us to determine
+ * the quality of radio transmission.
+ *
+ * Copyright (C) 2017 Robert Fraczkiewicz (aromring@gmail.com)
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ */
+#include "data.h"
+#include "rtl_433.h"
+#include "util.h"
+
+#define LACROSSE_TX141TH_BITLEN 40
+#define LACROSSE_TX141TH_BYTELEN 5 // = LACROSSE_TX141TH_BITLEN / 8
+#define LACROSSE_TX141TH_PACKETCOUNT 12
+
+typedef struct {
+ int32_t data; // First 4 data bytes compressed into 32-bit integer
+ int8_t count; // Count
+} data_and_count;
+
+static int lacrosse_tx141th_bv2_callback(bitbuffer_t *bitbuffer) {
+ bitrow_t *bb = bitbuffer->bb;
+ data_t *data;
+ char time_str[LOCAL_TIME_BUFLEN];
+ local_time_str(0, time_str);
+ int i,j,k,nbytes,npacket,kmax;
+ uint8_t id=0,status=0,battery_low=0,test=0,humidity=0,maxcount;
+ uint16_t temp_raw=0;
+ float temp_f=0.0;
+ data_and_count dnc[LACROSSE_TX141TH_PACKETCOUNT] = {0};
+
+ if (debug_output) {
+ bitbuffer_print(bitbuffer);
+ }
+
+ npacket=0; // Number of unique packets
+ for(i=0; i<BITBUF_ROWS; ++i) {
+ j=bitbuffer->bits_per_row[i];
+ if(j>=LACROSSE_TX141TH_BITLEN) {
+ nbytes=j/8;
+ for(j=0;j<nbytes;j+=LACROSSE_TX141TH_BYTELEN) {
+ uint32_t *d=(uint32_t *)(bb[i]+j);
+ uint8_t not_found=1;
+ for(k=0;k<npacket;++k) {
+ if(*d==dnc[k].data) {
+ ++(dnc[k].count);
+ not_found=0;
+ break;
+ }
+ }
+ if(not_found) {
+ dnc[npacket].data=*d;
+ dnc[npacket].count=1;
+ if(npacket+1<LACROSSE_TX141TH_PACKETCOUNT) ++npacket;
+ }
+ }
+ }
+ }
+
+ if (debug_output) {
+ fprintf(stderr, "%d unique packet(s)\n", npacket);
+ for(k=0;k<npacket;++k) {
+ fprintf(stderr, "%08x \t %d \n", dnc[k].data,dnc[k].count);
+ }
+ }
+
+ // Find the most frequent data packet, if necessary
+ kmax=0;
+ maxcount=0;
+ if(npacket>1) {
+ for(k=0;k<npacket;++k) {
+ if(dnc[k].count>maxcount) {
+ maxcount=dnc[k].count;
+ kmax=k;
+ }
+ }
+ }
+
+ // Unpack the data bytes back to eliminate dependence on the platform endiannes!
+ uint8_t *bytes=(uint8_t*)(&(dnc[kmax].data));
+ id=bytes[0];
+ status=bytes[1];
+ battery_low=(status & 0x80) >> 7;
+ test=(status & 0x40) >> 6;
+ temp_raw=((status & 0x0F) << 8) + bytes[2];
+ temp_f = 9.0*((float)temp_raw)/50.0-58.0; // Temperature in F
+ humidity = bytes[3];
+
+ if (0==id || 0==humidity || humidity > 100 || temp_f < -40.0 || temp_f > 140.0) {
+ if (debug_output) {
+ fprintf(stderr, "LaCrosse TX141TH-Bv2 data error\n");
+ }
+ return 0;
+ }
+
+ data = data_make("time", "Date and time", DATA_STRING, time_str,
+ "temperature", "Temperature in deg F", DATA_FORMAT, "%.2f F", DATA_DOUBLE, temp_f,
+ "humidity", "Humidity", DATA_FORMAT, "%u %%", DATA_INT, humidity,
+ "id", "Sensor ID", DATA_FORMAT, "%02x", DATA_INT, id,
+ "model", "", DATA_STRING, "LaCrosse TX141TH-Bv2 sensor",
+ "battery", "Battery", DATA_STRING, battery_low ? "LOW" : "OK",
+ "test", "Test?", DATA_STRING, test ? "Yes" : "No",
+ NULL);
+ data_acquired_handler(data);
+
+ return 1;
+
+}
+
+static char *output_fields[] = {
+ "time",
+ "temperature",
+ "humidity",
+ "id",
+ "model",
+ "battery",
+ "test",
+ NULL
+};
+
+r_device lacrosse_TX141TH_Bv2 = {
+ .name = "LaCrosse TX141TH-Bv2 sensor",
+ .modulation = OOK_PULSE_PWM_TERNARY,
+ .short_limit = 312, // short pulse is ~208 us, long pulse is ~417 us
+ .long_limit = 625, // long gap (with short pulse) is ~417 us, sync gap is ~833 us
+ .reset_limit = 1500, // maximum gap is 1250 us (long gap + longer sync gap on last repeat)
+ .json_callback = &lacrosse_tx141th_bv2_callback,
+ .disabled = 0,
+ .demod_arg = 2, // Longest pulses are startbits
+ .fields = output_fields,
+};
+
projects / rtl-433.git / blobdiff