Add BMP280/BME280 (tested only on BME); add SHT3x (bug: reads only once)

I2Csensors/SHT3x.c

@@ -0,0 +1,117 @@
+/*
+ * Copyright 2025 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+#include <usefull_macros.h>
+
+#include "SHT3x.h"
+#include "i2c.h"
+#include "sensors_private.h"
+
+// use single mode with high repeatability
+static uint8_t cmd_measure[]          = { 0x24, 0x00 };
+static uint8_t cmd_reset[]            = { 0x30, 0xa2 };
+static uint8_t cmd_break[]            = { 0x30, 0x93 };
+static uint8_t cmd_heater_on[]        = { 0x30, 0x6d };
+static uint8_t cmd_heater_off[]       = { 0x30, 0x66 };
+//static uint8_t cmd_read_status_reg[]  = { 0xf3, 0x2d };
+static uint8_t cmd_clear_status_reg[] = { 0x30, 0x41 };
+
+// maybe usefull to read heater status
+//#define SHT31_REG_HEATER_BIT 0x0d
+
+// documented timeout is 15ms, so let's wait 20
+#define MEASUREMENT_TIMEOUT     (0.02)
+
+static int s_init(sensor_t *s){
+    s->status = SENS_NOTINIT;
+    if(!i2c_write_raw(cmd_break, 2)){
+        DBG("Can't break old measurements");
+        return FALSE;
+    }
+    if(!i2c_write_raw(cmd_reset, 2)){
+        DBG("Can't make soft reset");
+        return FALSE;
+    }
+    if(!i2c_write_raw(cmd_clear_status_reg, 2)){
+        DBG("Can't clear status bits");
+        return FALSE;
+    }
+    if(!s->privdata) s->privdata = calloc(1, sizeof(double)); // used for start measurement time
+    s->status = SENS_RELAX;
+    return TRUE;
+}
+
+static int s_start(sensor_t *s){
+    if(s->status != SENS_RELAX) return FALSE;
+    s->status = SENS_BUSY;
+    if(!i2c_write_raw(cmd_measure, 2)){
+        DBG("Can't write start Tmeas");
+        s->status = SENS_ERR;
+        return FALSE;
+    }
+    *((double*)s->privdata) = sl_dtime();
+    return TRUE;
+}
+
+static uint8_t crc8(const uint8_t *data, int len){
+    uint8_t POLYNOMIAL = 0x31;
+    uint8_t crc = 0xFF;
+    for(int j = len; j; --j){
+        crc ^= *data++;
+        for(int i = 8; i; --i) crc = (crc & 0x80) ? (crc << 1) ^ POLYNOMIAL : (crc << 1);
+    }
+    return crc;
+}
+
+
+static sensor_status_t s_process(sensor_t *s){
+    if(s->status != SENS_BUSY) return s->status;
+    if(sl_dtime() - *((double*)s->privdata) < MEASUREMENT_TIMEOUT) return s->status;
+    uint8_t data[6];
+    if(!i2c_read_raw(data, 6)) return (s->status = SENS_ERR);
+    if(data[2] != crc8(data, 2) || data[5] != crc8(data + 3, 2)) return (s->status = SENS_ERR);
+    int32_t stemp = (int32_t)(((uint32_t)data[0] << 8) | data[1]);
+    stemp = ((4375 * stemp) >> 14) - 4500;
+    s->data.T = stemp / 100.;
+    uint32_t shum = ((uint32_t)data[3] << 8) | data[4];
+    shum = (625 * shum) >> 12;
+    s->data.H = shum / 100.0;
+    return (s->status = SENS_RDY);
+}
+
+static sensor_props_t s_props(sensor_t _U_ *s){
+    sensor_props_t p = {.T = 1, .H = 1};
+    return p;
+}
+
+static int s_heater(sensor_t _U_ *s, int on){
+    uint8_t *cmd = (on) ? cmd_heater_on : cmd_heater_off;
+    if(!i2c_write_raw(cmd, 2)) return FALSE;
+    return TRUE;
+}
+
+sensor_t SHT3x = {
+    .name = "SHT3x",
+    .address = 0x44,
+    .status = SENS_NOTINIT,
+    .init = s_init,
+    .start = s_start,
+    .heater = s_heater,
+    .process = s_process,
+    .properties = s_props,
+};