├── .gitignore ├── LICENSE ├── README.md ├── examples └── simpleRead.js ├── index.js ├── package-lock.json └── package.json /.gitignore: -------------------------------------------------------------------------------- 1 | # Dependency directories 2 | node_modules/ 3 | 4 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. 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We also recommend that a 185 | file or class name and description of purpose be included on the 186 | same "printed page" as the copyright notice for easier 187 | identification within third-party archives. 188 | 189 | Copyright [yyyy] [name of copyright owner] 190 | 191 | Licensed under the Apache License, Version 2.0 (the "License"); 192 | you may not use this file except in compliance with the License. 193 | You may obtain a copy of the License at 194 | 195 | http://www.apache.org/licenses/LICENSE-2.0 196 | 197 | Unless required by applicable law or agreed to in writing, software 198 | distributed under the License is distributed on an "AS IS" BASIS, 199 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 200 | See the License for the specific language governing permissions and 201 | limitations under the License. 202 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # pigpio-dht 2 | 3 | Dht sensor control using node.js and pigpio. Supported sensors are DHT11, DHT22 and AM2302. 4 | 5 | ## Installation 6 | 7 | 1. Install [pigpio C library](https://github.com/joan2937/pigpio). 8 | 2. Install module: `npm i pigpio-dht`. 9 | 10 | ## Usage 11 | 12 | ```javascript 13 | const dht = require('pigpio-dht'); 14 | const sensor = dht(dataPin, dhtType); 15 | ``` 16 | 17 | | Sensor | dhtType | 18 | |-----------------|:----------------:| 19 | | DHT11 | 11 | 20 | | DHT22 or AM2302 | 22 | 21 | 22 | ### Example 23 | 24 | ```javascript 25 | const dht = require('pigpio-dht'); 26 | 27 | const dataPin = 5; 28 | const dhtType = 22; //optional 29 | const sensor = dht(dataPin, dhtType); 30 | 31 | setInterval(() => { 32 | sensor.read(); 33 | }, 2500); // the sensor can only be red every 2 seconds 34 | 35 | sensor.on('result', data => { 36 | console.log(`temp: ${data.temperature}°c`); 37 | console.log(`rhum: ${data.humidity}%`); 38 | }); 39 | 40 | sensor.on('badChecksum', () => { 41 | console.log('checksum failed'); 42 | }); 43 | ``` 44 | 45 | ### Methods 46 | #### `read()` 47 | 48 | Start a new reading of the sensor. This can't be called more then once every second for the DHT11 sensor or once every 2 seconds for the DHT22 sensor. 49 | 50 | ### Events 51 | 52 | #### `start` 53 | 54 | Emitted when starting to read a value. 55 | 56 | #### `end` 57 | 58 | Emitted when the reading stops. This because it was complete, an error occurred or anything else. 59 | 60 | #### `result` 61 | 62 | - result object containing temperature and humidity 63 | 64 | Emitted when the reading was completed successful. 65 | 66 | #### `badChecksum` 67 | 68 | Emitted when finished reading but the checksum was invalid. 69 | 70 | ## Built With 71 | 72 | * [pigpio](https://github.com/fivdi/pigpio) - Gpio wrapper for nodejs 73 | 74 | ## Versioning 75 | 76 | We use [SemVer](http://semver.org/) for versioning. For the versions available, see the [tags on this repository](https://github.com/depuits/pigpio-dht/tags). 77 | -------------------------------------------------------------------------------- /examples/simpleRead.js: -------------------------------------------------------------------------------- 1 | 'use strict'; 2 | const dht = require('../'); 3 | 4 | const dataPin = 2; 5 | const sensor = dht(dataPin); 6 | 7 | setInterval(() => { 8 | sensor.read(); 9 | }, 2500); // the sensor can only be red every 2 seconds 10 | 11 | sensor.on('result', data => { 12 | console.log(`temp: ${data.temperature}°c`); 13 | console.log(`rhum: ${data.humidity}%`); 14 | }); 15 | 16 | sensor.on('badChecksum', () => { 17 | console.log('checksum failed'); 18 | }); 19 | -------------------------------------------------------------------------------- /index.js: -------------------------------------------------------------------------------- 1 | 'use strict'; 2 | 3 | const pigpio = require('pigpio'); 4 | const Gpio = pigpio.Gpio; 5 | const eventEmitter = require('events').EventEmitter; 6 | 7 | module.exports = function(pin, type) { 8 | const dht = Object.create(new eventEmitter()); 9 | const gpio = new Gpio(pin, { mode: Gpio.OUTPUT, pullUpDown: Gpio.PUD_OFF }); 10 | 11 | dht.reading = false; 12 | 13 | var lastHighTick = 0; 14 | var bits = 0; 15 | 16 | var rhumHigh = 0; 17 | var rhumLow = 0; 18 | var tempHigh = 0; 19 | var tempLow = 0; 20 | var checksum = 0; 21 | 22 | // default type is dht22 23 | type = type || 22; 24 | 25 | function startReading() { 26 | if (dht.reading) { 27 | // cancel out if we are already reading 28 | return false; 29 | } 30 | dht.emit('start'); 31 | // Trigger a new relative humidity and temperature reading. 32 | // write low for 18 ms 33 | gpio.digitalWrite(0); 34 | // after that let the line go high and start reading 35 | setTimeout(() => { 36 | // reset all values 37 | bits = -2; // initialized at -2 because the first 2 lows are the ack 38 | rhumHigh = 0; 39 | rhumLow = 0; 40 | tempHigh = 0; 41 | tempLow = 0; 42 | checksum = 0; 43 | 44 | // Set the pin high, particularly for when this is the second or later reading. 45 | gpio.digitalWrite(1); 46 | lastHighTick = pigpio.getTick(); 47 | 48 | // start reading input 49 | gpio.mode(Gpio.INPUT); 50 | gpio.enableAlert(); 51 | }, 18); 52 | 53 | return true; 54 | } 55 | function endReading() { 56 | dht.reading = false; 57 | gpio.disableAlert(); 58 | gpio.mode(Gpio.OUTPUT); 59 | dht.emit('end'); 60 | } 61 | 62 | function interpretDht11() { 63 | let rhum = rhumHigh; 64 | let temp = tempHigh; 65 | 66 | return { temperature: temp, humidity: rhum }; 67 | } 68 | function interpretDht22() { 69 | let rhum = ((rhumHigh << 8) + rhumLow) * 0.1; 70 | 71 | // check the temperature sign 72 | let mult = (tempHigh & 128) ? -0.1 : 0.1; 73 | tempHigh = tempHigh & 127; // strip the sign bit 74 | let temp = ((tempHigh << 8) + tempLow) * mult; 75 | 76 | return { temperature: temp, humidity: rhum }; 77 | } 78 | 79 | gpio.on('alert', (level, tick) => { 80 | // Accumulate the 40 data bits. Format into 5 bytes, humidity high, 81 | // humidity low, temperature high, temperature low, checksum. 82 | 83 | // bits are only accumulated on the low level 84 | if (level == 0) { 85 | let diff = pigpio.tickDiff(lastHighTick, tick); 86 | 87 | // Edge length determines if bit is 1 or 0. 88 | let val = 0; 89 | // low bit is between 26 and 28 µs 90 | // high bit is 70 µs 91 | // So we check on the value in between to avoid small differences 92 | if (diff >= 50) { 93 | val = 1; 94 | if (diff >= 200) { // Bad bit? 95 | checksum = 256; // Force bad checksum. 96 | } 97 | } 98 | 99 | if (bits < 0) { 100 | // header bits 101 | // we don't need to do anything with these 102 | } else if (bits < 8) { 103 | // in humidity high byte 104 | rhumHigh = (rhumHigh << 1) + val; 105 | } else if (bits < 16) { 106 | // in humidity low byte 107 | rhumLow = (rhumLow << 1) + val; 108 | } else if (bits < 24) { 109 | // in temp high byte 110 | tempHigh = (tempHigh << 1) + val; 111 | } else if (bits < 32) { 112 | // in temp low byte 113 | tempLow = (tempLow << 1) + val; 114 | } else { 115 | // In checksum byte. 116 | checksum = (checksum << 1) + val; 117 | 118 | if (bits == 39) { 119 | // 40th bit received. 120 | endReading(); 121 | 122 | let total = rhumHigh + rhumLow + tempHigh + tempLow; 123 | 124 | // Is checksum ok? 125 | if ((total & 255) == checksum) { 126 | let res = (type == 11) ? interpretDht11() : interpretDht22(); 127 | 128 | dht.emit('result', res); 129 | } else { 130 | dht.emit('badChecksum'); 131 | } 132 | } 133 | } 134 | 135 | ++bits; 136 | } else if (level == 1) { 137 | lastHighTick = tick; 138 | } 139 | }); 140 | 141 | return Object.assign(dht, { 142 | gpio, 143 | read: startReading 144 | }); 145 | }; 146 | -------------------------------------------------------------------------------- /package-lock.json: -------------------------------------------------------------------------------- 1 | { 2 | "name": "pigpio-dht", 3 | "version": "1.1.1", 4 | "lockfileVersion": 1, 5 | "requires": true, 6 | "dependencies": { 7 | "bindings": { 8 | "version": "1.3.0", 9 | "resolved": "https://registry.npmjs.org/bindings/-/bindings-1.3.0.tgz", 10 | "integrity": "sha512-DpLh5EzMR2kzvX1KIlVC0VkC3iZtHKTgdtZ0a3pglBZdaQFjt5S9g9xd1lE+YvXyfd6mtCeRnrUfOLYiTMlNSw==" 11 | }, 12 | "pigpio": { 13 | "version": "1.2.0", 14 | "resolved": "https://registry.npmjs.org/pigpio/-/pigpio-1.2.0.tgz", 15 | "integrity": "sha512-DGopuMdjmRguqydLZ3A16PYOiJWtl705aGF3a48Tnc6woLyts4Zj01FklJYgTqFMCZy4ZBHg49xe+W5yG5+jOw==", 16 | "requires": { 17 | "bindings": "^1.3.0", 18 | "nan": "^2.11.1" 19 | }, 20 | "dependencies": { 21 | "nan": { 22 | "version": "2.11.1", 23 | "resolved": "https://registry.npmjs.org/nan/-/nan-2.11.1.tgz", 24 | "integrity": "sha512-iji6k87OSXa0CcrLl9z+ZiYSuR2o+c0bGuNmXdrhTQTakxytAFsC56SArGYoiHlJlFoHSnvmhpceZJaXkVuOtA==" 25 | } 26 | } 27 | } 28 | } 29 | } 30 | -------------------------------------------------------------------------------- /package.json: -------------------------------------------------------------------------------- 1 | { 2 | "name": "pigpio-dht", 3 | "version": "1.1.1", 4 | "description": "Dht22 control using node.js and pigpio.", 5 | "main": "index.js", 6 | "scripts": { 7 | "test": "echo \"Error: no test specified\" && exit 1" 8 | }, 9 | "repository": { 10 | "type": "git", 11 | "url": "git+https://github.com/depuits/pigpio-dht.git" 12 | }, 13 | "keywords": [ 14 | "DHT", 15 | "DHT11", 16 | "DHT22", 17 | "AM2302", 18 | "pigpio", 19 | "raspberry", 20 | "pi" 21 | ], 22 | "author": "depuits", 23 | "license": "ISC", 24 | "bugs": { 25 | "url": "https://github.com/depuits/pigpio-dht/issues" 26 | }, 27 | "homepage": "https://github.com/depuits/pigpio-dht#readme", 28 | "dependencies": { 29 | "pigpio": "^1.2.0" 30 | } 31 | } 32 | --------------------------------------------------------------------------------