Après avoir bien joué avec le pluviométre1… , j’ai acheté ce WH0531 
et je ne le regrette pas… pour environ 20 euros il fait le boulot…
Le problème est que le capteur ne communique qu’avec l’afficheur et moi je souhaitais récupérer les données pour enrichir ma BD…
En fouillant un peu je suis tombé sur ce site:
https://lucsmall.com/2012/04/27/weather-station-hacking-part-1/
et c’était parti pour une passerelle RF433-Internet adaptée à ce pluviomètre…
Quelques modifications pour intercepter complétement les paquets envoyés par le WH0531
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/* Updated code for receiving data from WH2 weather station This code implements timeouts to make decoding more robust Decodes received packets and writes a summary of each packet to the Arduino's serial port Created by Luc Small on 19 July 2013. Released into the public domain. */ // Read data from 433MHz receiver on digital pin 2 #define RF_IN 2 // For better efficiency, the port is read directly // the following two lines should be changed appropriately // if the line above is changed. #define RF_IN_RAW PIND2 #define RF_IN_PIN PIND // Port that is hooked to LED to indicate a packet has been received #define LED_PACKET A2 #define COUNTER_RATE 3200-1 // 16,000,000Hz / 3200 = 5000 interrupts per second, ie. 200us between interrupts // 1 is indicated by 500uS pulse // wh2_accept from 2 = 400us to 3 = 600us #define IS_HI_PULSE(interval) (interval >= 2 && interval <= 3) // 0 is indicated by ~1500us pulse // wh2_accept from 7 = 1400us to 8 = 1600us #define IS_LOW_PULSE(interval) (interval >= 7 && interval <= 8) // worst case packet length // 6 bytes x 8 bits x (1.5 + 1) = 120ms; 120ms = 200us x 600 #define HAS_TIMED_OUT(interval) (interval > 600) // we expect 1ms of idle time between pulses // so if our pulse hasn't arrived by 1.2ms, reset the wh2_packet_state machine // 6 x 200us = 1.2ms #define IDLE_HAS_TIMED_OUT(interval) (interval > 6) // our expected pulse should arrive after 1ms // we'll wh2_accept it if it arrives after // 4 x 200us = 800us #define IDLE_PERIOD_DONE(interval) (interval >= 4) // Shorthand for tests //#define RF_HI (digitalRead(RF_IN) == HIGH) //#define RF_LOW (digitalRead(RF_IN) == LOW) #define RF_HI (bit_is_set(RF_IN_PIN, RF_IN_RAW)) #define RF_LOW (bit_is_clear(RF_IN_PIN, RF_IN_RAW)) // wh2_flags #define GOT_PULSE 0x01 #define LOGIC_HI 0x02 volatile byte wh2_flags = 0; volatile byte wh2_packet_state = 0; volatile int wh2_timeout = 0; #define nbp 7 //la modification la plus importante !... byte wh2_packet[nbp]; byte wh2_calculated_crc; ISR(TIMER1_COMPA_vect) { static byte sampling_state = 0; static byte count; static boolean was_low = false; switch (sampling_state) { case 0: // waiting wh2_packet_state = 0; if (RF_HI) { if (was_low) { count = 0; sampling_state = 1; was_low = false; } } else { was_low = true; } break; case 1: // acquiring first pulse count++; // end of first pulse if (RF_LOW) { if (IS_HI_PULSE(count)) { wh2_flags = GOT_PULSE | LOGIC_HI; sampling_state = 2; count = 0; } else if (IS_LOW_PULSE(count)) { wh2_flags = GOT_PULSE; // logic low sampling_state = 2; count = 0; } else { sampling_state = 0; } } break; case 2: // observe 1ms of idle time count++; if (RF_HI) { if (IDLE_HAS_TIMED_OUT(count)) { sampling_state = 0; } else if (IDLE_PERIOD_DONE(count)) { sampling_state = 1; count = 0; } } break; } if (wh2_timeout > 0) { wh2_timeout++; if (HAS_TIMED_OUT(wh2_timeout)) { wh2_packet_state = 0; wh2_timeout = 0; } } } void setup() { Serial.begin(9600); Serial.println("BetterWH2"); pinMode(LED_PACKET, OUTPUT); pinMode(RF_IN, INPUT); TCCR1A = 0x00; TCCR1B = 0x09; TCCR1C = 0x00; OCR1A = COUNTER_RATE; TIMSK1 = 0x02; // enable interrupts sei(); } void loop() { static unsigned long old = 0, packet_count = 0, bad_count = 0, average_interval; unsigned long spacing, now; byte i; if (wh2_flags) { if (wh2_accept()) { // calculate the CRC wh2_calculate_crc(); now = millis(); spacing = now - old; old = now; packet_count++; average_interval = now / packet_count; if (!wh2_valid()) { bad_count++; } // flash green led to say got packet digitalWrite(LED_PACKET, HIGH); delay(100); digitalWrite(LED_PACKET, LOW); Serial.print(packet_count, DEC); Serial.print(" | "); Serial.print(bad_count, DEC); Serial.print(" | "); /* Serial.print(spacing, DEC); Serial.print(" | "); Serial.print(average_interval, DEC); Serial.print(" | ");*/ for (i = 0; i < nbp; i++) { Serial.print("0x"); Serial.print(wh2_packet[i], HEX); Serial.print("/"); Serial.print(wh2_packet[i], DEC); Serial.print(" "); } for (i = 0; i < nbp; i++) { // Serial.print(wh2_packet[i], BIN); Serial.print(ByteToBin(wh2_packet[i])); if (i<(nbp-1)) Serial.print("-"); } Serial.print(" SensorID:0x"); Serial.print(wh2_sensor_id(), HEX); Serial.print(" T:"); Serial.print(wh2_temperature(), DEC); Serial.print(" R:"); Serial.print(wh2_rain(), DEC); Serial.print((wh2_valid() ? " OK." : " BAD.")); Serial.println(); } wh2_flags = 0x00; } } // processes new pulse boolean wh2_accept() { static byte packet_no, bit_no, history; // reset if in initial wh2_packet_state if (wh2_packet_state == 0) { // should history be 0, does it matter? history = 0xFF; wh2_packet_state = 1; // enable wh2_timeout wh2_timeout = 1; } // fall thru to wh2_packet_state one // acquire preamble if (wh2_packet_state == 1) { // shift history right and store new value history <<= 1; // store a 1 if required (right shift along will store a 0) if (wh2_flags & LOGIC_HI) { history |= 0x01; } // check if we have a valid start of frame // xxxxx110 if ((history & B00000111) == B00000110) { // need to clear packet, and counters packet_no = 0; // start at 1 becuase only need to acquire 7 bits for first packet byte. bit_no = 1; wh2_packet[0] = wh2_packet[1] = wh2_packet[2] = wh2_packet[3] = wh2_packet[4] = 0; // we've acquired the preamble wh2_packet_state = 2; } return false; } // acquire packet if (wh2_packet_state == 2) { wh2_packet[packet_no] <<= 1; if (wh2_flags & LOGIC_HI) { wh2_packet[packet_no] |= 0x01; } bit_no ++; if (bit_no > 7) { bit_no = 0; packet_no ++; } if (packet_no > (nbp - 1)) { // start the sampling process from scratch wh2_packet_state = 0; // clear wh2_timeout wh2_timeout = 0; return true; } } return false; } void wh2_calculate_crc() { wh2_calculated_crc = crc8(wh2_packet, nbp-1); } bool wh2_valid() { return (wh2_calculated_crc == wh2_packet[nbp-1]); } int wh2_sensor_id() { return (wh2_packet[0] << 4) + (wh2_packet[1] >> 4); } int wh2_rain() { return wh2_packet[3] + 256 * wh2_packet[4]; } /* Temperature in deci-degrees. e.g. 251 = 25.1 */ int wh2_temperature() { int temperature; temperature = ((wh2_packet[1] & B00000111) << 8) + wh2_packet[2] - 400; // make negative if (wh2_packet[1] & B00001000) { temperature = -temperature; } return temperature; } uint8_t crc8( uint8_t *addr, uint8_t len) { uint8_t crc = 0; // Indicated changes are from reference CRC-8 function in OneWire library while (len--) { uint8_t inbyte = *addr++; for (uint8_t i = 8; i; i--) { uint8_t mix = (crc ^ inbyte) & 0x80; // changed from & 0x01 crc <<= 1; // changed from right shift if (mix) crc ^= 0x31;// changed from 0x8C; inbyte <<= 1; // changed from right shift } } return crc; } String ByteToBin(byte b) { String r = ""; for (int j = 0; j < 8; j++) { if (bitRead(b, j) == 1) r = "1" + r; else r = "0" + r; } return r; } |
Résultat:
Il intercepte les paquets destinés à l’afficheur 
et envoie sur ma BD internet uniquement les données RAIN (R:octets 4 et 5), BD consultable içi.
Un module similaire permet d’asservir mon arrosage automatique…