create library and make two examples of usage

I2Csensors/examples/single_sensor.c

@@ -0,0 +1,121 @@
+/*
+ * 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 <unistd.h>
+#include <usefull_macros.h>
+
+#include "i2csensorsPTH.h"
+
+typedef struct{
+    char *device;
+    char *sensor;
+    int slaveaddr;
+    int list;
+    int presmm;     // pressure in mm instead of hPa
+    int help;
+    int heater;     // turn on/off heater (if present)
+} glob_pars;
+
+static glob_pars G = {
+    .device = "/dev/i2c-6",
+    .heater = -1,
+};
+
+static sl_option_t cmdlnopts[] = {
+    {"help",    NO_ARGS,    NULL,   'h',    arg_int,    APTR(&G.help),      "show this help"},
+    {"device",  NEED_ARG,   NULL,   'd',    arg_string, APTR(&G.device),    "I2C device path"},
+    {"address", NEED_ARG,   NULL,   'a',    arg_int,    APTR(&G.slaveaddr), "sensor's address (if not default)"},
+    {"sensor",  NEED_ARG,   NULL,   's',    arg_string, APTR(&G.sensor),    "sensor's name"},
+    {"list",    NO_ARGS,    NULL,   'l',    arg_int,    APTR(&G.list),      "list all supported sensors"},
+    {"presmm",  NO_ARGS,    NULL,   'm',    arg_int,    APTR(&G.presmm),    "pressure in mmHg instead of hPa"},
+    {"heater",  NEED_ARG,   NULL,   'H',    arg_int,    APTR(&G.heater),    "turn on/off heater (if present)"},
+    end_option
+};
+
+static int start(sensor_t *s, uint8_t addr){
+    if(!sensor_init(s, addr)){
+        WARNX("Can't init sensor");
+        return FALSE;
+    }
+    if(!sensor_start(s)){
+        WARNX("Can't start measurements");
+        return FALSE;
+    }
+    return TRUE;
+}
+
+static int printdata(sensor_t *s){
+    sensor_data_t D;
+    if(!sensor_getdata(s, &D)){
+        WARNX("Can't read data, try again");
+        if(!sensor_start(s)) WARNX("Oops: can't start");
+        return FALSE;
+    }
+    sensor_props_t props = sensor_properties(s);
+    if(props.T) printf("T=%.2f\n", D.T);
+    if(props.H) printf("H=%.2f\n", D.H);
+    if(props.P){
+        if(G.presmm) D.P *= 0.750062;
+        printf("P=%.1f\n", D.P);
+    }
+    return TRUE;
+}
+
+int main(int argc, char **argv){
+    sl_init();
+    sl_parseargs(&argc, &argv, cmdlnopts);
+    if(G.help) sl_showhelp(-1, cmdlnopts);
+    if(G.list){
+        char *l = sensors_list();
+        green("\nSupported sensors:\n");
+        printf(l); printf("\n\n");
+        FREE(l);
+        return 0;
+    }
+    if(!G.sensor) ERRX("Point sensor's name");
+    if(G.slaveaddr && (G.slaveaddr < 8 || G.slaveaddr > 0x77)) ERRX("I2C address should be 7-bit and not forbidden");
+    if(!sensors_open(G.device)) ERR("Can't open %s", G.device);
+    sensor_t* s = sensor_new(G.sensor);
+    if(!s){ WARNX("Can't find sensor `%s` in supported list", G.sensor); goto clo; }
+    if(G.heater > -1){
+        sensor_props_t props = sensor_properties(s);
+        if(props.htr){
+            if(!sensor_init(s, G.slaveaddr)) ERRX("Can't init device");
+            if(!sensor_heater(s, G.heater)) WARNX("Cant run heater command");
+            else green("Heater is %s\n", G.heater ? "on" : "off");
+        }else ERRX("The sensor have no heater");
+        return 0;
+    }
+    if(!start(s, G.slaveaddr)) goto clo;
+    while(1){
+        sensor_status_t status = sensor_process(s);
+        if(status == SENS_RDY){ // data ready - get it
+            if(!printdata(s)) continue;
+            break;
+        }else if(status == SENS_ERR){
+            WARNX("Error in measurement, try again");
+            if(!start(s, G.slaveaddr)) break;
+        }
+        usleep(10000);
+    }
+    sensor_delete(&s);
+
+clo:
+    sensors_close();
+    return 0;
+}