it was fun

README.md

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+# Awair Data Grabber
+
+## Disclaimer
+
+This project retrieves sensor data from an Awair Element through its enabled Local API and displays it on an 128x64 OLED. The IdeaSpark ESP8266 board uses different OLED pins than a standard NodeMCU ESP8266.
+
+## Requirements
+
+- ESP8266 Arduino core
+- ArduinoJson
+- U8g2
+
+## Usage
+
+- enable the Local API for your Awair Element in the Awair Home app
+- set `OLED_SCL` and `OLED_SDA` according to your board specification, the current defaults are GPIO 14 and GPIO 12
+- set `SSID` and `PASSWD` for a network that can reach the Awair Element
+- set the full `SERVER_URL`, for example `http://awair-elem-123456.local/air-data/latest`
+- flash the firmware, the sensor data will be displayed after a successful request

awair_data_grabber/awair_data_grabber.ino

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+#include <ESP8266WiFi.h>
+#include <ESP8266HTTPClient.h>
+#include <ArduinoJson.h>
+#include <U8g2lib.h>
+
+#ifdef U8X8_HAVE_HW_SPI
+#include <SPI.h>
+#endif
+#ifdef U8X8_HAVE_HW_I2C
+#include <Wire.h>
+#endif
+
+#define OLED_SCL 14
+#define OLED_SDA 12
+
+#define UPDATE_INTERVAL_MS 1000
+
+#define SERVER_URL "http://awair-server/air-data/latest"
+
+#define SSID "-"
+#define PASSWD "-"
+
+WiFiClient client;
+HTTPClient http;
+
+struct AwairData{
+  private:
+    int score = 0;
+    float temp = .0f;
+    float humid = .0f;
+    int co2 = 0;
+    int voc = 0;
+    int pm25 = 0;
+
+    bool updated = false;
+
+    template <typename T>
+    void update_var(T* var, T value){
+      if(*var == value) return;
+      *var = value;
+      updated = true;
+    }
+
+  public:
+    void set_score(int value){ update_var<int>(&score, value); }
+    void set_temp(float value){ update_var<float>(&temp, value); }
+    void set_humid(float value){ update_var<float>(&humid, value); }
+    void set_co2(int value){ update_var<int>(&co2, value); }
+    void set_voc(int value){ update_var<int>(&voc, value); }
+    void set_pm25(int value){ update_var<int>(&pm25, value); }
+
+    int get_score(void) const { return score; }
+    float get_temp(void) const { return temp; }
+    float get_humid(void) const { return humid; }
+    int get_co2(void) const { return co2; }
+    int get_voc(void) const { return voc; }
+    int get_pm25(void) const { return pm25; }
+
+    void update(int score, float temp, float humid, int co2, int voc, int pm25){
+      set_score(score);
+      set_temp(temp);
+      set_humid(humid);
+      set_co2(co2);
+      set_voc(voc);
+      set_pm25(pm25);
+    }
+
+    bool has_updated(void) const { return updated; }
+    void reset_updated(void){ updated = false; }
+};
+
+class Panel{
+  private:
+    U8G2_SSD1306_128X64_NONAME_F_SW_I2C panel;
+
+  public:
+    Panel() : panel(U8G2_R0, OLED_SCL, OLED_SDA, U8X8_PIN_NONE){}
+
+    void begin(void){
+      panel.begin();
+    }
+
+    void show_failed(void){
+      panel.clearBuffer();
+      panel.setFont(u8g2_font_ncenB08_tr);
+      panel.drawStr(0, 10, "Something failed");
+      panel.sendBuffer();
+    }
+
+    void update(const AwairData& data){
+      char buffer[16];
+
+      panel.clearBuffer();
+
+      panel.setFont(u8g2_font_ncenB08_tr);
+      panel.drawStr(0, 9, "Score:");
+
+      snprintf(buffer, sizeof(buffer), "%d", data.get_score());
+      panel.drawStr(42, 9, buffer);
+
+      panel.drawHLine(0, 12, 128);
+
+      panel.setFont(u8g2_font_6x10_tr);
+
+      panel.drawStr(0, 24, "Temp");
+      snprintf(buffer, sizeof(buffer), "%.1f C", data.get_temp());
+      panel.drawStr(0, 35, buffer);
+
+      panel.drawStr(68, 24, "Humid");
+      snprintf(buffer, sizeof(buffer), "%.1f %%", data.get_humid());
+      panel.drawStr(68, 35, buffer);
+
+      panel.drawStr(0, 47, "CO2");
+      panel.drawStr(47, 47, "VOC");
+      panel.drawStr(87, 47, "PM2.5");
+
+      snprintf(buffer, sizeof(buffer), "%d", data.get_co2());
+      panel.drawStr(0, 59, buffer);
+
+      snprintf(buffer, sizeof(buffer), "%d", data.get_voc());
+      panel.drawStr(47, 59, buffer);
+
+      snprintf(buffer, sizeof(buffer), "%d", data.get_pm25());
+      panel.drawStr(87, 59, buffer);
+
+      panel.sendBuffer();
+    }
+};
+
+bool parseAwairJson(const String& payload, AwairData& data) {
+  JsonDocument doc;
+
+  auto error = deserializeJson(doc, payload);
+  if(error){
+    Serial.print("JSON error: ");
+    Serial.println(error.c_str());
+    return false;
+  }
+
+  int score = doc["score"] | 0;
+  float temp = doc["temp"] | .0f;
+  float humid = doc["humid"] | .0f;
+  int co2 = doc["co2"] | 0;
+  int voc = doc["voc"] | 0;
+  int pm25 = doc["pm25"] | 0;
+
+  data.update(score, temp, humid, co2, voc, pm25);
+
+  return true;
+}
+
+int request_data(AwairData* data){
+  if(!http.begin(client, SERVER_URL)){
+    Serial.println("Failed to request URL!");
+    return 1;
+  }
+
+  int http_code = http.GET();
+  int result = 1;
+  if(http_code == HTTP_CODE_OK){
+    if(parseAwairJson(http.getString(), *data)) result = 0;
+  }
+  else{
+    Serial.print("Failed GET request: ");
+    Serial.println(http_code, 10);
+  }
+
+  http.end();
+
+  return result;
+}
+
+Panel panel;
+AwairData data;
+
+void setup() {
+  Serial.begin(115200);
+  
+  panel.begin();
+
+  http.setTimeout(3000);
+
+  WiFi.begin(SSID, PASSWD);
+  while(WiFi.status() != WL_CONNECTED) delay(100);
+
+  Serial.println("Connected!");
+}
+
+void loop() {
+  /*
+  static auto start = millis() - UPDATE_INTERVAL_MS;
+  auto current = millis();
+  
+  if(current - start < UPDATE_INTERVAL_MS) return;
+  start = current;
+  */
+
+  if(WiFi.status() != WL_CONNECTED){ delay(100); return; }
+
+  Serial.println("Requesting data...");
+  if(request_data(&data) != 0){ panel.show_failed(); }
+
+  if(data.has_updated()){
+    Serial.println("Got new data -> Updating...");
+    panel.update(data);
+    data.reset_updated();
+  }
+  else Serial.println("Got data but nothing new!");
+
+  Serial.println("---------- ---------- ----------\n");
+  delay(UPDATE_INTERVAL_MS); // simple delay is enough <- no state machine
+}