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https://github.com/thooge/esp32-nmea2000-obp60.git
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131 lines
3.0 KiB
C++
131 lines
3.0 KiB
C++
#include "GwSHTXX.h"
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#ifdef _GWSHT4X
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uint8_t crc8(const uint8_t *data, int len) {
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/*
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*
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* CRC-8 formula from page 14 of SHT spec pdf
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*
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* Test data 0xBE, 0xEF should yield 0x92
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*
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* Initialization data 0xFF
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* Polynomial 0x31 (x8 + x5 +x4 +1)
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* Final XOR 0x00
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*/
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const uint8_t POLYNOMIAL(0x31);
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uint8_t crc(0xFF);
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for (int j = len; j; --j) {
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crc ^= *data++;
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for (int i = 8; i; --i) {
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crc = (crc & 0x80) ? (crc << 1) ^ POLYNOMIAL : (crc << 1);
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}
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}
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return crc;
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}
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bool SHT4X::begin(TwoWire* wire, uint8_t addr) {
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_addr = addr;
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_wire = wire;
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int error;
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_wire->beginTransmission(addr);
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error = _wire->endTransmission();
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if (error == 0) {
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return true;
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}
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return false;
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}
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bool SHT4X::update() {
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uint8_t readbuffer[6];
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uint8_t cmd = SHT4x_NOHEAT_HIGHPRECISION;
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uint16_t duration = 10;
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if (_heater == SHT4X_NO_HEATER) {
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if (_precision == SHT4X_HIGH_PRECISION) {
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cmd = SHT4x_NOHEAT_HIGHPRECISION;
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duration = 10;
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}
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if (_precision == SHT4X_MED_PRECISION) {
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cmd = SHT4x_NOHEAT_MEDPRECISION;
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duration = 5;
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}
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if (_precision == SHT4X_LOW_PRECISION) {
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cmd = SHT4x_NOHEAT_LOWPRECISION;
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duration = 2;
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}
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}
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if (_heater == SHT4X_HIGH_HEATER_1S) {
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cmd = SHT4x_HIGHHEAT_1S;
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duration = 1100;
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}
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if (_heater == SHT4X_HIGH_HEATER_100MS) {
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cmd = SHT4x_HIGHHEAT_100MS;
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duration = 110;
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}
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if (_heater == SHT4X_MED_HEATER_1S) {
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cmd = SHT4x_MEDHEAT_1S;
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duration = 1100;
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}
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if (_heater == SHT4X_MED_HEATER_100MS) {
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cmd = SHT4x_MEDHEAT_100MS;
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duration = 110;
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}
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if (_heater == SHT4X_LOW_HEATER_1S) {
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cmd = SHT4x_LOWHEAT_1S;
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duration = 1100;
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}
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if (_heater == SHT4X_LOW_HEATER_100MS) {
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cmd = SHT4x_LOWHEAT_100MS;
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duration = 110;
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}
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// _i2c.writeByte(_addr, cmd, 1);
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_wire->beginTransmission(_addr);
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_wire->write(cmd);
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_wire->write(1);
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_wire->endTransmission();
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delay(duration);
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_wire->requestFrom(_addr, (uint8_t)6);
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for (uint16_t i = 0; i < 6; i++) {
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readbuffer[i] = _wire->read();
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}
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if (readbuffer[2] != crc8(readbuffer, 2) ||
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readbuffer[5] != crc8(readbuffer + 3, 2)) {
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return false;
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}
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float t_ticks = (uint16_t)readbuffer[0] * 256 + (uint16_t)readbuffer[1];
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float rh_ticks = (uint16_t)readbuffer[3] * 256 + (uint16_t)readbuffer[4];
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cTemp = -45 + 175 * t_ticks / 65535;
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humidity = -6 + 125 * rh_ticks / 65535;
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humidity = min(max(humidity, (float)0.0), (float)100.0);
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return true;
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}
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void SHT4X::setPrecision(sht4x_precision_t prec) {
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_precision = prec;
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}
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sht4x_precision_t SHT4X::getPrecision(void) {
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return _precision;
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}
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void SHT4X::setHeater(sht4x_heater_t heat) {
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_heater = heat;
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}
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sht4x_heater_t SHT4X::getHeater(void) {
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return _heater;
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}
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#endif |