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- // -----------------------------------------------------------------------------
- // AM2320 Humidity & Temperature sensor over I2C
- // Copyright (C) 2018 by Mustafa Tufan
- // -----------------------------------------------------------------------------
-
- #if SENSOR_SUPPORT && AM2320_SUPPORT
-
- #pragma once
-
- #undef I2C_SUPPORT
- #define I2C_SUPPORT 1 // Explicitly request I2C support.
-
- #include "Arduino.h"
- #include "I2CSensor.h"
-
- // https://akizukidenshi.com/download/ds/aosong/AM2320.pdf
- #define AM2320_I2C_READ_REGISTER_DATA 0x03 // Read one or more data registers
- #define AM2320_I2C_WRITE_MULTIPLE_REGISTERS 0x10 // Multiple sets of binary data to write multiple registers
- /*
- Register | Address | Register | Address | Register | Address | Register | Address
- -----------------+---------+--------------------+---------+-------------------------+---------+-----------+--------
- High humidity | 0x00 | Model High | 0x08 | Users register a high | 0x10 | Retention | 0x18
- Low humidity | 0x01 | Model Low | 0x09 | Users register a low | 0x11 | Retention | 0x19
- High temperature | 0x02 | The version number | 0x0A | Users register 2 high | 0x12 | Retention | 0x1A
- Low temperature | 0x03 | Device ID(24-31)Bit| 0x0B | Users register 2 low | 0x13 | Retention | 0x1B
- Retention | 0x04 | Device ID(24-31)Bit| 0x0C | Retention | 0x14 | Retention | 0x1C
- Retention | 0x05 | Device ID(24-31)Bit| 0x0D | Retention | 0x15 | Retention | 0x1D
- Retention | 0x06 | Device ID(24-31)Bit| 0x0E | Retention | 0x16 | Retention | 0x1E
- Retention | 0x07 | Status Register | 0x0F | Retention | 0x17 | Retention | 0x1F
- */
-
- class AM2320Sensor : public I2CSensor {
-
- public:
-
- // ---------------------------------------------------------------------
- // Public
- // ---------------------------------------------------------------------
-
- AM2320Sensor(): I2CSensor() {
- _count = 2;
- _sensor_id = SENSOR_AM2320_ID;
- }
-
- // ---------------------------------------------------------------------
- // Sensor API
- // ---------------------------------------------------------------------
-
- // Initialization method, must be idempotent
- void begin() {
- if (!_dirty) return;
-
- // I2C auto-discover
- unsigned char addresses[] = {0x23, 0x5C, 0xB8};
- _address = _begin_i2c(_address, sizeof(addresses), addresses);
- if (_address == 0) return;
-
- _ready = true;
- _dirty = false;
- }
-
- // Descriptive name of the sensor
- String description() {
- char buffer[25];
- snprintf(buffer, sizeof(buffer), "AM2320 @ I2C (0x%02X)", _address);
- return String(buffer);
- }
-
- // Descriptive name of the slot # index
- String slot(unsigned char index) {
- return description();
- };
-
- // Type for slot # index
- unsigned char type(unsigned char index) {
- if (index == 0) return MAGNITUDE_TEMPERATURE;
- if (index == 1) return MAGNITUDE_HUMIDITY;
- return MAGNITUDE_NONE;
- }
-
- // Pre-read hook (usually to populate registers with up-to-date data)
- void pre() {
- _error = SENSOR_ERROR_OK;
- _read();
- }
-
- // Current value for slot # index
- double value(unsigned char index) {
- if (index == 0) return _temperature;
- if (index == 1) return _humidity;
- return 0;
- }
-
- protected:
-
- // ---------------------------------------------------------------------
- // Protected
- // ---------------------------------------------------------------------
-
- /*
- // Get device model, version, device_id
-
- void _init() {
- i2c_wakeup(address);
- delayMicroseconds(800);
-
- unsigned char _buffer[11];
-
- // 0x08 = read address
- // 7 = number of bytes to read
- if (i2c_write_uint8(_address, AM2320_I2C_READ_REGISTER_DATA, 0x08, 7) != I2C_TRANS_SUCCESS) {
- _error = SENSOR_ERROR_TIMEOUT;
- return false;
- }
-
- uint16_t model = (_buffer[2] << 8) | _buffer[3];
- uint8_t version = _buffer[4];
- uint32_t device_id = _buffer[8] << 24 | _buffer[7] << 16 | _buffer[6] << 8 | _buffer[5];
- }
- */
-
- void _read() {
-
- i2c_wakeup(address);
-
- // waiting time of at least 800 μs, the maximum 3000 μs
- delayMicroseconds(800); // just to be on safe side
-
- // 0x00 = read address
- // 4 = number of bytes to read
- if (i2c_write_uint8(_address, AM2320_I2C_READ_REGISTER_DATA, 0x00, 4) != I2C_TRANS_SUCCESS) {
- _error = SENSOR_ERROR_TIMEOUT;
- return;
- }
-
- unsigned char _buffer[8];
-
- // waiting time of at least 800 μs, the maximum 3000 μs
- delayMicroseconds(800 + ((3000-800)/2) );
- i2c_read_buffer(_address, _buffer, 8);
-
- // Humidity : 01F4 = (1×256)+(F×16)+4 = 500 => humidity = 500÷10 = 50.0 %
- // 0339 = (3×256)+(3×16)+9 = 825 => humidity = 825÷10 = 82.5 %
- // Temperature: 00FA = (F×16)+A = 250 => temperature = 250÷10 = 25.0 C
- // 0115 = (1×256)+(1×16)+5 = 277 => temperature = 277÷10 = 27.7 C
- // Temperature resolution is 16Bit, temperature highest bit (Bit 15) is equal to 1 indicates a negative temperature
-
- // _buffer 0 = function code
- // _buffer 1 = number of bytes
- // _buffer 2-3 = high/low humidity
- // _buffer 4-5 = high/low temperature
- // _buffer 6-7 = CRC low/high
-
- unsigned int responseCRC = 0;
- responseCRC = ((responseCRC | _buffer[7]) << 8 | _buffer[6]);
-
- if (responseCRC == _CRC16(_buffer)) {
- int foo = (_buffer[2] << 8) | _buffer[3];
- _humidity = foo / 10.0;
-
- foo = ((_buffer[4] & 0x7F) << 8) | _buffer[5]; // clean bit 15 and merge
- _temperature = foo / 10.0;
-
- if (_buffer[4] & 0x80) { // is bit 15 == 1
- _temperature = _temperature * -1; // negative temperature
- }
-
- _error = SENSOR_ERROR_OK;
- } else {
- _error = SENSOR_ERROR_CRC;
- return;
- }
- }
-
- unsigned int _CRC16(unsigned char buffer[]) {
- unsigned int crc16 = 0xFFFF;
-
- for (unsigned int i = 0; i < 6; i++) {
- crc16 ^= buffer[i];
-
- for (unsigned int b = 8; b != 0; b--) {
- if (crc16 & 0x01) { // is lsb set
- crc16 >>= 1;
- crc16 ^= 0xA001;
- } else {
- crc16 >>= 1;
- }
- }
- }
-
- return crc16;
- }
-
- double _temperature = 0;
- double _humidity = 0;
- };
-
- #endif // SENSOR_SUPPORT && AM2320_SUPPORT
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