first commit

6 files changed, 216 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..77ab86a
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,5 @@
+.pio
+.cache
+sdkconfig*
+compile_commands.json
+**CMakeLists.txt
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..e650c04
--- /dev/null
+++ b/README.md
@@ -0,0 +1,3 @@
+# home-temperature-sensor
+
+Read temperature from `ds18x20` sensors and push results to a Prometheus Pushgateway.
diff --git a/platformio.ini b/platformio.ini
new file mode 100644
index 0000000..49676a8
--- /dev/null
+++ b/platformio.ini
@@ -0,0 +1,19 @@
+[env]
+platform = espressif32
+framework = espidf
+monitor_speed = 115200
+build_flags =
+  -DWIFI_SSID="None"
+  -DWIFI_PASS="XXXX"
+  -DPUSH_GATEWAY_HOST="192.168.0.2"
+  -DPUSH_GATEWAY_PORT="30091"
+lib_compat_mode = off
+lib_deps =
+  ; for https://github.com/UncleRus/esp-idf-lib/tree/master/components/ds18x20
+  lbernstone/UncleRus@^1.0.1
+
+[env:nodemcu-32s]
+board = nodemcu-32s
+
+[env:lolin_d32]
+board = lolin_d32
diff --git a/src/main.c b/src/main.c
new file mode 100644
index 0000000..4908709
--- /dev/null
+++ b/src/main.c
@@ -0,0 +1,92 @@
+#include "esp_http_client.h"
+#include "esp_sleep.h"
+#include "lwip/netdb.h"
+#include "wifi.h"
+#include <ds18x20.h>
+#include <stdio.h>
+
+#define ST(A) #A
+#define STR(A) ST(A)
+
+#ifndef MAX_SENSOR_COUNT
+#define MAX_SENSOR_COUNT 10
+#endif
+
+#ifndef TEMPERATURE_SENSOR_PIN
+#define TEMPERATURE_SENSOR_PIN GPIO_NUM_17
+#endif
+
+static float temps[MAX_SENSOR_COUNT];
+
+esp_err_t _http_event_handler(esp_http_client_event_t *evt) { return ESP_OK; }
+
+void app_main() {
+  const int wakeup_time_sec = 900;
+  const wifi_sta_config_t wifi_config = {
+      .ssid = STR(WIFI_SSID),
+      .password = STR(WIFI_PASS),
+  };
+
+  ds18x20_addr_t addrs[MAX_SENSOR_COUNT];
+  size_t sensor_count = 0;
+
+  gpio_config_t io_conf = {};
+  io_conf.pin_bit_mask = (1ULL << TEMPERATURE_SENSOR_PIN);
+  io_conf.mode = GPIO_MODE_INPUT;
+  io_conf.intr_type = GPIO_INTR_DISABLE;
+  io_conf.pull_down_en = GPIO_PULLDOWN_DISABLE;
+  io_conf.pull_up_en = GPIO_PULLUP_DISABLE;
+  gpio_config(&io_conf);
+
+  ESP_ERROR_CHECK(ds18x20_scan_devices(TEMPERATURE_SENSOR_PIN, addrs,
+                                       MAX_SENSOR_COUNT, &sensor_count));
+  printf("Found %d sensors\n", sensor_count);
+
+  ESP_ERROR_CHECK(wifi_init(&wifi_config));
+
+  esp_http_client_config_t config = {
+      .host = STR(PUSH_GATEWAY_HOST),
+      .port = PUSH_GATEWAY_PORT,
+      .path = "/metrics/job/ds1820",
+      .transport_type = HTTP_TRANSPORT_OVER_TCP,
+      .event_handler = _http_event_handler,
+  };
+
+  esp_http_client_handle_t client = esp_http_client_init(&config);
+
+  ds18x20_measure_and_read_multi(TEMPERATURE_SENSOR_PIN, addrs, sensor_count,
+                                 temps);
+  for (int i = 0; i < sensor_count; i++) {
+    char *post_data;
+    char *url;
+
+    if (0 > asprintf(&post_data,
+                     "# TYPE ds1820_sensor "
+                     "gauge\nds1820_sensor %f\n",
+                     temps[i])) {
+      free(post_data);
+      goto sleep;
+    }
+
+    if (0 > asprintf(&url, "/metrics/job/ds1820/addr/%08x", (uint32_t)addrs[i])) {
+      free(post_data);
+      free(url);
+      goto sleep;
+    }
+
+    printf("Sensor: %08x - %fC\n", (uint32_t)addrs[i], temps[i]);
+
+    esp_http_client_set_url(client, url);
+    esp_http_client_set_method(client, HTTP_METHOD_POST);
+    esp_http_client_set_post_field(client, post_data, strlen(post_data));
+    esp_http_client_perform(client);
+    free(post_data);
+    free(url);
+  }
+
+sleep:
+  esp_http_client_cleanup(client);
+  _wifi_deinit();
+  esp_sleep_enable_timer_wakeup(wakeup_time_sec * 1000000);
+  esp_deep_sleep_start();
+}
diff --git a/src/wifi.c b/src/wifi.c
new file mode 100644
index 0000000..593cf72
--- /dev/null
+++ b/src/wifi.c
@@ -0,0 +1,93 @@
+#include "esp_log.h"
+#include "esp_wifi.h"
+#include "freertos/event_groups.h"
+#include "nvs_flash.h"
+
+/* FreeRTOS event group to signal when we are connected*/
+static EventGroupHandle_t s_wifi_event_group;
+
+/* The event group allows multiple bits for each event, but we only care about
+ * two events:
+ * - we are connected to the AP with an IP
+ * - we failed to connect after the maximum amount of retries */
+#define WIFI_CONNECTED_BIT BIT0
+#define WIFI_FAIL_BIT BIT1
+
+static const char *TAG = "wifi";
+
+static int s_retry_num = 0;
+static int s_retry_max = 0;
+
+static void event_handler(void *arg, esp_event_base_t event_base,
+                          int32_t event_id, void *event_data) {
+  if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_START) {
+    esp_wifi_connect();
+  } else if (event_base == WIFI_EVENT &&
+             event_id == WIFI_EVENT_STA_DISCONNECTED) {
+    if (s_retry_num < s_retry_max) {
+      esp_wifi_connect();
+      s_retry_num++;
+      ESP_LOGI(TAG, "retry to connect to the AP");
+    } else {
+      xEventGroupSetBits(s_wifi_event_group, WIFI_FAIL_BIT);
+    }
+    ESP_LOGI(TAG, "connect to the AP fail");
+  } else if (event_base == IP_EVENT && event_id == IP_EVENT_STA_GOT_IP) {
+    ip_event_got_ip_t *event = (ip_event_got_ip_t *)event_data;
+    ESP_LOGI(TAG, "IP:" IPSTR, IP2STR(&event->ip_info.ip));
+    s_retry_num = 0;
+    xEventGroupSetBits(s_wifi_event_group, WIFI_CONNECTED_BIT);
+  }
+}
+
+esp_err_t _wifi_deinit(void) { return esp_wifi_stop(); }
+
+esp_err_t wifi_init(wifi_sta_config_t const *sta_config, uint8_t retries) {
+  esp_event_handler_instance_t instance_any_id;
+  esp_event_handler_instance_t instance_got_ip;
+  wifi_config_t wifi_config = {.sta = *sta_config};
+
+  s_retry_max = retries;
+
+  ESP_ERROR_CHECK(nvs_flash_init());
+  ESP_ERROR_CHECK(esp_netif_init());
+
+  ESP_LOGI(TAG, "SSID: '%s'", sta_config->ssid);
+  ESP_LOGI(TAG, "PASS: '%s'", sta_config->password);
+
+  s_wifi_event_group = xEventGroupCreate();
+  ESP_ERROR_CHECK(esp_event_loop_create_default());
+
+  esp_netif_create_default_wifi_sta();
+  wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
+  ESP_ERROR_CHECK(esp_wifi_init(&cfg));
+
+  ESP_ERROR_CHECK(esp_event_handler_instance_register(
+      WIFI_EVENT, ESP_EVENT_ANY_ID, &event_handler, NULL, &instance_any_id));
+  ESP_ERROR_CHECK(esp_event_handler_instance_register(
+      IP_EVENT, IP_EVENT_STA_GOT_IP, &event_handler, NULL, &instance_got_ip));
+
+  ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_STA));
+  ESP_ERROR_CHECK(esp_wifi_set_config(WIFI_IF_STA, &wifi_config));
+  ESP_ERROR_CHECK(esp_wifi_start());
+
+  /* Waiting until either the connection is established (WIFI_CONNECTED_BIT) or
+   * connection failed for the maximum number of re-tries (WIFI_FAIL_BIT). The
+   * bits are set by event_handler() (see above) */
+  EventBits_t bits = xEventGroupWaitBits(s_wifi_event_group,
+                                         WIFI_CONNECTED_BIT | WIFI_FAIL_BIT,
+                                         pdFALSE, pdFALSE, portMAX_DELAY);
+
+  /* xEventGroupWaitBits() returns the bits before the call returned, hence we
+   * can test which event actually happened. */
+  if (bits & WIFI_CONNECTED_BIT) {
+    ESP_LOGI(TAG, "CONNECTED");
+    return ESP_OK;
+  } else if (bits & WIFI_FAIL_BIT) {
+    ESP_LOGI(TAG, "FAIL TO CONNECT");
+    return ESP_FAIL;
+  } else {
+    ESP_LOGE(TAG, "UNEXPECTED EVENT");
+    return ESP_FAIL;
+  }
+}
diff --git a/src/wifi.h b/src/wifi.h
new file mode 100644
index 0000000..8898a4b
--- /dev/null
+++ b/src/wifi.h
@@ -0,0 +1,4 @@
+#include "esp_wifi.h"
+
+esp_err_t wifi_init(wifi_sta_config_t const *sta_config);
+esp_err_t _wifi_deinit(void);