110 lines
2.0 KiB
C++
110 lines
2.0 KiB
C++
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#pragma once
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/**
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* air quality sensor
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* https://sensirion.com/media/documents/984E0DD5/61644B8B/Sensirion_Gas_Sensors_Datasheet_SGP30.pdf
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*/
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template <typename I2C> class SGP30 {
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private:
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I2C& i2c;
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static constexpr const uint8_t ADDR = 0x58;
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static constexpr const char* NAME = "SGP30";
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static constexpr const uint16_t CMD_IAQ_INIT = 0x2003;
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static constexpr const uint16_t CMD_IAQ_MEASURE = 0x2008;
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static constexpr const uint16_t CMD_GET_SERIAL = 0x3682;
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public:
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SGP30(I2C& i2c) : i2c(i2c) {
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}
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void init() {
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sendCommand(CMD_IAQ_INIT);
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}
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/** is the device present on the bus? */
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bool isPresent() {
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return i2c.query(ADDR);
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}
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struct Result {
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uint16_t co2e;
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uint16_t tvoc;
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};
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/** should be called ~ every second */
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Result measure() {
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sendCommand(CMD_IAQ_MEASURE);
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vTaskDelay(100 / portTICK_PERIOD_MS);
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uint8_t tmp[6];
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i2c.readRaw(ADDR, 6, tmp);
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Result res;
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res.co2e = (tmp[0]<<8) | (tmp[1]<<0);
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res.tvoc = (tmp[3]<<8) | (tmp[4]<<0);
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return res;
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}
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void getSerial() {
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struct Serial {
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uint8_t v1[2];
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uint8_t crc1;
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uint8_t v2[2];
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uint8_t crc2;
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uint8_t v3[2];
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uint8_t crc3;
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} serial;
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sendCommand(CMD_GET_SERIAL);
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uint8_t tmp[9];
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i2c.readRaw(ADDR, 9, &serial);
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/*
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uint8_t a = calcCRC(tmp+0, 2);
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uint8_t b = calcCRC(tmp+3, 2);
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uint8_t c = calcCRC(tmp+6, 2);
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printf("%d %d %d %d\n", tmp[0], tmp[1], tmp[2], a);
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printf("%d %d %d %d\n", tmp[3], tmp[4], tmp[5], b);
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printf("%d %d %d %d\n", tmp[6], tmp[7], tmp[8], c);
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*/
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}
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private:
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void sendCommand(uint16_t cmd) {
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uint8_t tmp[2];
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tmp[0] = cmd >> 8;
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tmp[1] = cmd >> 0;
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i2c.writeRaw(ADDR, 2, tmp);
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}
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static uint8_t calcCRC(const uint8_t* data, uint8_t len) {
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uint8_t crc = 0xff;
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for (uint8_t i = 0; i < len; i++) {
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crc ^= data[i];
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for (uint8_t j = 0; j < 8; j++) {
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if ((crc & 0x80) != 0) {
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crc = (uint8_t)((crc << 1) ^ 0x31);
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} else {
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crc <<= 1;
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}
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}
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}
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return crc;
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}
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};
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