Étape 5: Code de l’appareil
Nous allons commencer à coder ! Lorsque vous travaillez avec imp électrique, vous aurez besoin de deux sections du code : une pour le périphérique et un autre pour l’agent. Merci à Thomas Byrne pour la fourniture de la classe pour gérer le capteur DHT11 dans Github. Voici le code de l’appareil (un peu long car il a la classe pour gérer les DHT11) :
<br><p>const SPICLK = 937.5;<br>// Class to read the DHT11 temperature/humidity sensor // These sensors us a proprietary one-wire protocol. The imp // emulates this protocol with SPI. // To use: // - tie MOSI to MISO with a 10k resistor // - tie MISO to the data line on the sensor class DHT11 { static STARTTIME_LOW = 0.001000; // 1 ms low time for start static STARTTIME_HIGH = 0.000020; // 20 us min high time for start static STARTTIME_SENSOR = 0.000080; // 80 us low / 80 us high "ACK" from sensor on START static MARKTIME = 0.000050; // 50 us low pulse between 0 or 1 marks static ZERO = 0.000026; // 26 us high for "0" static ONE = 0.000075; // 70 us high for "1" spi = null; clkspeed = null; bittime = null; bytetime = null; start_low_bits = null; start_low_bytes = null; start_high_bits = null; start_high_bytes = null; start_ack_bits = null; start_ack_bytes = null; mark_bits = null; mark_bytes = null; zero_bits = null; zero_bytes = null; one_bits = null; one_bytes = null; // class constructor // Input: // _spi: a pre-configured SPI peripheral (e.g. spi257) // _clkspeed: the speed the SPI has been configured to run at // Return: (None) constructor(_spi, _clkspeed) { this.spi = _spi; this.clkspeed = _clkspeed; bittime = 1.0 / (clkspeed * 1000); bytetime = 8.0 * bittime; start_low_bits = STARTTIME_LOW / bittime; start_low_bytes = (start_low_bits / 8); start_high_bits = STARTTIME_HIGH / bittime; start_high_bytes = (start_high_bits / 8); start_ack_bits = STARTTIME_SENSOR / bittime; start_ack_bytes = (start_ack_bits / 8); mark_bits = MARKTIME / bittime; mark_bytes = (mark_bits / 8); zero_bits = ZERO / bittime; zero_bytes = (zero_bits / 8); one_bits = ONE / bittime; one_bytes = (one_bits / 8); } // helper function // given a long blob, find times between transitions and parse to // temp and humidity values. Assumes 40-bit return value (16 humidity / 16 temp / 8 checksum) // Input: // hexblob (blob of arbitrary length) // Return: // table containing: // "rh": relative humidity (float) // "temp": temperature in celsius (float) // if read fails, rh and temp will return 0 function parse(hexblob) { local laststate = 0; local lastbitidx = 0; local gotack = false; local rawidx = 0; local result = blob(5); // 2-byte humidity, 2-byte temp, 1-byte checksum local humid = 0; local temp = 0; // iterate through each bit of each byte of the returned signal for (local byte = 0; byte < hexblob.len(); byte++) { for (local bit = 7; bit >= 0; bit--) { local thisbit = (hexblob[byte] & (0x01 << bit)) ? 1:0; if (thisbit != laststate) { if (thisbit) { // low-to-high transition; watch to see how long it is high laststate = 1; lastbitidx = (8 * byte) + (7 - bit); } else { // high-to-low transition; laststate = 0; local idx = (8 * byte) + (7 - bit); local hightime = (idx - lastbitidx) * bittime; // we now have one valid bit of info. Figure out what symbol it is. local resultbyte = (rawidx / 8); local resultbit = 7 - (rawidx % 8); //server.log(format("bit %d of byte %d",resultbit, resultbyte)); if (hightime < ZERO) { // this is a zero if (gotack) { // don't record any data before the ACK is seen result[resultbyte] = result[resultbyte] & ~(0x01 << resultbit); rawidx++; } } else if (hightime < ONE) { // this is a one if (gotack) { result[resultbyte] = result[resultbyte] | (0x01 << resultbit); rawidx++; } } else { // this is a START ACK gotack = true; } } } } } //server.log(format("parsed: 0x %02x%02x %02x%02x %02x",result[0],result[1],result[2],result[3],result[4])); humid = (result[0] * 1.0) + (result[1] / 1000.0); if (result[2] & 0x80) { // negative temperature result[2] = ((~result[2]) + 1) & 0xff; } temp = (result[2] * 1.0) + (result[3] / 1000.0); if (((result[0] + result[1] + result[2] + result[3]) & 0xff) != result[4]) { return {"rh":0,"temp":0}; } else { return {"rh":humid,"temp":temp}; } } // read the sensor // Input: (none) // Return: // table containing: // "rh": relative humidity (float) // "temp": temperature in celsius (float) // if read fails, rh and temp will return 0 function read() { local bloblen = start_low_bytes + start_high_bytes + (40 * (mark_bytes + one_bytes)); local startblob = blob(bloblen); for (local i = 0; i < start_low_bytes; i++) { startblob.writen(0x00,'b'); } for (local j = start_low_bytes; j < bloblen; j++) { startblob.writen(0xff,'b'); } //server.log(format("Sending %d bytes", startblob.len())); local result = spi.writeread(startblob); return parse(result); } } rele <- hardware.pin9; spi <- hardware.spi257;</p><p>while(1){ clkspeed <- spi.configure(MSB_FIRST, SPICLK); dht11 <- DHT11(spi, clkspeed); data <- dht11.read(); server.log(format("Relative Humidity: %0.1f",data.rh)+" %"); server.log(format("Temperature: %0.1f C",data.temp)); agent.send("temp",data.temp); imp.sleep(1);</p><p>}</p>
