ESP8266/NodeMCU read Analog Input and send to Raspberry Pi via Serial/USB

This example of ESP8266/NodeMCU read input from A0, and output to Serial. The receiving side is a Raspberry Pi 3 running Raspbian Jessie with PIXEL and Arduino IDE installed, the result is display graphically using Arduino IDE's Serial Plotter. All job done on Raspberry Pi 3. ESP8266/NodeMCU connect to the Raspberry Pi 3 with USB.


To run the whole in Raspberry Pi, you have to:
- Install Arduino IDE on Raspberry Pi/Raspbian Jessie with PIXEL
- Add Arduino core for ESP8266 to Arduino IDE

The simple program run on ESP8266/NodeMCU, ESP8266_AnalogIn_SerialOut.ino. (Suppose it work on other Arduino also, such as Uno.)

const int analogIn = A0;
int analogVal = 0;
bool led = 1;

void setup() {
  Serial.begin(9600);
  pinMode(LED_BUILTIN, OUTPUT);
}

void loop() {

  digitalWrite(LED_BUILTIN, led);
  led = !led; 
  analogVal = analogRead(analogIn);
  Serial.println(analogVal);
  delay(500);
}

Next:
- A Python example run on Raspberry Pi 3/Raspbian Jessie with PIXEL, to plot the serial data graphically using matplotlib library.