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https://github.com/eddyem/eddys_snippets.git
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122 lines
3.8 KiB
C
122 lines
3.8 KiB
C
/*
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* Copyright 2025 Edward V. Emelianov <edward.emelianoff@gmail.com>.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdio.h>
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#include <usefull_macros.h>
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#include "SHT3x.h"
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#include "i2c.h"
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#include "sensors_private.h"
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// use single mode with high repeatability
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static uint8_t cmd_measure[] = { 0x24, 0x00 };
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static uint8_t cmd_reset[] = { 0x30, 0xa2 };
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static uint8_t cmd_break[] = { 0x30, 0x93 };
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static uint8_t cmd_heater_on[] = { 0x30, 0x6d };
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static uint8_t cmd_heater_off[] = { 0x30, 0x66 };
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//static uint8_t cmd_read_status_reg[] = { 0xf3, 0x2d };
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static uint8_t cmd_clear_status_reg[] = { 0x30, 0x41 };
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// maybe usefull to read heater status
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//#define SHT31_REG_HEATER_BIT 0x0d
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// documented timeout is 15ms, so let's wait 20
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#define MEASUREMENT_TIMEOUT (0.02)
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static int s_init(sensor_t *s){
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s->status = SENS_NOTINIT;
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if(!i2c_write_raw(cmd_break, 2)){
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DBG("Can't break old measurements");
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return FALSE;
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}
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if(!i2c_write_raw(cmd_reset, 2)){
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DBG("Can't make soft reset");
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return FALSE;
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}
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if(!i2c_write_raw(cmd_clear_status_reg, 2)){
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DBG("Can't clear status bits");
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return FALSE;
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}
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if(!s->privdata) s->privdata = calloc(1, sizeof(double)); // used for start measurement time
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s->status = SENS_RELAX;
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return TRUE;
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}
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static int s_start(sensor_t *s){
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if(s->status != SENS_RELAX) return FALSE;
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s->status = SENS_BUSY;
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if(!i2c_write_raw(cmd_measure, 2)){
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DBG("Can't write start Tmeas");
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s->status = SENS_ERR;
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return FALSE;
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}
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*((double*)s->privdata) = sl_dtime();
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return TRUE;
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}
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static uint8_t crc8(const uint8_t *data, int len){
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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) crc = (crc & 0x80) ? (crc << 1) ^ POLYNOMIAL : (crc << 1);
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}
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return crc;
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}
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static sensor_status_t s_process(sensor_t *s){
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if(s->status != SENS_BUSY) return s->status;
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uint8_t data[6];
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int ans = i2c_read_raw(data, 6);
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if(sl_dtime() - *((double*)s->privdata) < MEASUREMENT_TIMEOUT){
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if(!ans) return s->status; // poll ACK
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}
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if(!ans) return (s->status = SENS_ERR); // timeout!
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i2c_write_raw(cmd_clear_status_reg, 2); // need to write any command or sensor will widthraw into itself
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if(data[2] != crc8(data, 2) || data[5] != crc8(data + 3, 2)) return (s->status = SENS_ERR); // CRC error
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int32_t stemp = (int32_t)(((uint32_t)data[0] << 8) | data[1]);
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stemp = ((4375 * stemp) >> 14) - 4500;
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s->data.T = stemp / 100.;
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uint32_t shum = ((uint32_t)data[3] << 8) | data[4];
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shum = (625 * shum) >> 12;
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s->data.H = shum / 100.0;
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return (s->status = SENS_RDY);
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}
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static sensor_props_t s_props(sensor_t _U_ *s){
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sensor_props_t p = {.T = 1, .H = 1};
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return p;
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}
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static int s_heater(sensor_t _U_ *s, int on){
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uint8_t *cmd = (on) ? cmd_heater_on : cmd_heater_off;
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if(!i2c_write_raw(cmd, 2)) return FALSE;
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return TRUE;
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}
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sensor_t SHT3x = {
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.name = "SHT3x",
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.address = 0x44,
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.status = SENS_NOTINIT,
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.init = s_init,
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.start = s_start,
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.heater = s_heater,
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.process = s_process,
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.properties = s_props,
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};
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