194 lines
7.1 KiB
C++
Executable File
194 lines
7.1 KiB
C++
Executable File
// -----------------------------------------------------------------------------
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// AM2320 Humidity & Temperature sensor over I2C
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// Copyright (C) 2018 by Mustafa Tufan
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// -----------------------------------------------------------------------------
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#if SENSOR_SUPPORT && AM2320_SUPPORT
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#pragma once
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#include "Arduino.h"
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#include "I2CSensor.h"
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// https://akizukidenshi.com/download/ds/aosong/AM2320.pdf
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#define AM2320_I2C_READ_REGISTER_DATA 0x03 // Read one or more data registers
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#define AM2320_I2C_WRITE_MULTIPLE_REGISTERS 0x10 // Multiple sets of binary data to write multiple registers
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/*
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Register | Address | Register | Address | Register | Address | Register | Address
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-----------------+---------+--------------------+---------+-------------------------+---------+-----------+--------
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High humidity | 0x00 | Model High | 0x08 | Users register a high | 0x10 | Retention | 0x18
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Low humidity | 0x01 | Model Low | 0x09 | Users register a low | 0x11 | Retention | 0x19
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High temperature | 0x02 | The version number | 0x0A | Users register 2 high | 0x12 | Retention | 0x1A
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Low temperature | 0x03 | Device ID(24-31)Bit| 0x0B | Users register 2 low | 0x13 | Retention | 0x1B
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Retention | 0x04 | Device ID(24-31)Bit| 0x0C | Retention | 0x14 | Retention | 0x1C
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Retention | 0x05 | Device ID(24-31)Bit| 0x0D | Retention | 0x15 | Retention | 0x1D
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Retention | 0x06 | Device ID(24-31)Bit| 0x0E | Retention | 0x16 | Retention | 0x1E
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Retention | 0x07 | Status Register | 0x0F | Retention | 0x17 | Retention | 0x1F
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*/
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class AM2320Sensor : public I2CSensor {
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public:
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// ---------------------------------------------------------------------
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// Public
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// ---------------------------------------------------------------------
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AM2320Sensor(): I2CSensor() {
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_count = 2;
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_sensor_id = SENSOR_AM2320_ID;
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}
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// ---------------------------------------------------------------------
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// Sensor API
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// ---------------------------------------------------------------------
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// Initialization method, must be idempotent
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void begin() {
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if (!_dirty) return;
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// I2C auto-discover
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unsigned char addresses[] = {0x23, 0x5C, 0xB8};
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_address = _begin_i2c(_address, sizeof(addresses), addresses);
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if (_address == 0) return;
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_ready = true;
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_dirty = false;
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}
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// Descriptive name of the sensor
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String description() {
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char buffer[25];
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snprintf(buffer, sizeof(buffer), "AM2320 @ I2C (0x%02X)", _address);
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return String(buffer);
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}
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// Descriptive name of the slot # index
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String slot(unsigned char index) {
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return description();
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};
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// Type for slot # index
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unsigned char type(unsigned char index) {
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if (index == 0) return MAGNITUDE_TEMPERATURE;
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if (index == 1) return MAGNITUDE_HUMIDITY;
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return MAGNITUDE_NONE;
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}
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// Pre-read hook (usually to populate registers with up-to-date data)
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void pre() {
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_error = SENSOR_ERROR_OK;
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_read();
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}
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// Current value for slot # index
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double value(unsigned char index) {
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if (index == 0) return _temperature;
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if (index == 1) return _humidity;
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return 0;
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}
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protected:
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// ---------------------------------------------------------------------
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// Protected
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// ---------------------------------------------------------------------
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/*
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// Get device model, version, device_id
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void _init() {
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i2c_wakeup();
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delayMicroseconds(800);
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unsigned char _buffer[11];
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// 0x08 = read address
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// 7 = number of bytes to read
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if (i2c_write_uint8(_address, AM2320_I2C_READ_REGISTER_DATA, 0x08, 7) != I2C_TRANS_SUCCESS) {
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_error = SENSOR_ERROR_TIMEOUT;
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return false;
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}
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uint16_t model = (_buffer[2] << 8) | _buffer[3];
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uint8_t version = _buffer[4];
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uint32_t device_id = _buffer[8] << 24 | _buffer[7] << 16 | _buffer[6] << 8 | _buffer[5];
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}
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*/
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void _read() {
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i2c_wakeup();
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// waiting time of at least 800 μs, the maximum 3000 μs
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delayMicroseconds(800); // just to be on safe side
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// 0x00 = read address
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// 4 = number of bytes to read
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if (i2c_write_uint8(_address, AM2320_I2C_READ_REGISTER_DATA, 0x00, 4) != I2C_TRANS_SUCCESS) {
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_error = SENSOR_ERROR_TIMEOUT;
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return false;
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}
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unsigned char _buffer[8];
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// waiting time of at least 800 μs, the maximum 3000 μs
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delayMicroseconds(800 + ((3000-800)/2) );
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i2c_read_buffer(_address, _buffer, 8);
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// Humidity : 01F4 = (1×256)+(F×16)+4 = 500 => humidity = 500÷10 = 50.0 %
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// 0339 = (3×256)+(3×16)+9 = 825 => humidity = 825÷10 = 82.5 %
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// Temperature: 00FA = (F×16)+A = 250 => temperature = 250÷10 = 25.0 C
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// 0115 = (1×256)+(1×16)+5 = 277 => temperature = 277÷10 = 27.7 C
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// Temperature resolution is 16Bit, temperature highest bit (Bit 15) is equal to 1 indicates a negative temperature
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// _buffer 0 = function code
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// _buffer 1 = number of bytes
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// _buffer 2-3 = high/low humidity
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// _buffer 4-5 = high/low temperature
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// _buffer 6-7 = CRC low/high
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unsigned int responseCRC = 0;
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responseCRC = ((responseCRC | _buffer[7]) << 8 | _buffer[6]);
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if (responseCRC == _CRC16(_buffer)) {
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int foo = (_buffer[2] << 8) | _buffer[3];
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_humidity = foo / 10.0;
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foo = ((_buffer[4] & 0x7F) << 8) | _buffer[5]; // clean bit 15 and merge
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_temperature = foo / 10.0;
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if (_buffer[4] & 0x80) { // is bit 15 == 1
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_temperature = _temperature * -1; // negative temperature
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}
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_error = SENSOR_ERROR_OK;
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} else {
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_error = SENSOR_ERROR_CRC;
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return;
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}
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}
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unsigned int _CRC16(unsigned char buffer[]) {
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unsigned int crc16 = 0xFFFF;
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for (unsigned int i = 0; i < 6; i++) {
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crc16 ^= buffer[i];
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for (unsigned int b = 8; b != 0; b--) {
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if (crc16 & 0x01) { // is lsb set
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crc16 >>= 1;
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crc16 ^= 0xA001;
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} else {
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crc16 >>= 1;
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}
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}
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}
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return crc16;
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}
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double _temperature = 0;
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double _humidity = 0;
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};
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#endif // SENSOR_SUPPORT && AM2320_SUPPORT
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