ASMSA PlatformIO ESP8266 Tutorial

main-simple.cpp

#include <Arduino.h>

const uint8_t PIN_PWR = 15;

float r1 = 10.0f;
float r2 = 10.0f;
float r3 = 10.0f;

float r2r3 = r2 + r3;

float rE = 1 / ((1 / r1) + (1 / r2r3));


void setup() {
  Serial.begin(115200);
  
  pinMode(A0, INPUT);

  pinMode(PIN_PWR, OUTPUT);
  digitalWrite(PIN_PWR, 1);
}

void loop() {
  float sample = analogRead(A0) * 3.0f / 1.1f;
  Serial.printf("Voltage = %.0f mV\n", sample);
  
  float deltaV = (3.3f * 1000) - sample;
  float current = deltaV / rE;
  Serial.printf("Current = %.0f mA\n", current);

  float power = deltaV * current / 1000;
  Serial.printf("Power = %.0f mW\n", power);


  delay(2000);
}

main.cpp

/*******************************************************************
// ASMSA PlatformIO ESP8266 Tutorial
// https://git.io/fjqKF
// https://gist.github.com/EEParker/2025bcf45f291e03e02e486b0db8c5da
******************************************************************//
  
#include <Arduino.h>
#include <LiquidCrystal_I2C.h>
#include <Wire.h>

// initialize the LCD
const uint8_t LCD_ADDR = 0x3F; // sometime the address is 0x27

const uint8_t LCD_ROWS = 2;  // 2 rows of 
const uint8_t LCD_COLS = 16; // 16 characters each

const uint8_t LCD_SDA = 5; // I2C Data Pin
const uint8_t LCD_SCL = 4;  // I2C Clock Pin

LiquidCrystal_I2C lcd(LCD_ADDR, LCD_ROWS, LCD_COLS);

// Define the circuit
const float r1 = 30.0f;
const float r2 = 10.0f;

const float R1 = r1; // Monitored Element
const float R2 = 1 / ( (1 / r1) + (1 / r2) ); // Equivalenced Resistance formula

const float V = 3000.f; // Reference voltage analog

// define user functions
void measureVoltage();

void setup() {
  // turn on the serial port for logging
  Serial.begin(115200);

  // set the analog port to input (read values)
  pinMode(A0, INPUT);

  // Initialize Grove Power
  pinMode(15, OUTPUT);
  digitalWrite(15, 1);

  // initialize the lcd
  Wire.begin(LCD_SDA, LCD_SCL);
  lcd.init();
  lcd.backlight();
}

void loop() {
  // measure and print the values
  measureVoltage();

  // sleep for 1 second (1000 ms) before measuring again
  delay(1000);
}

/**
 * Measure the voltage using the analog port
 * and estimate the current based on R values.
 */ 
void measureVoltage() {

  // take a number of samples, then average them for more accuracy
  const int samples = 100;
  long sum = 0;
  for(int i = 0; i < samples; i++)
  {
     sum += analogRead(A0);
     delay(2);
  }
  sum = sum / samples;
  
  // calculate the voltage
  float v = sum * 3.0f / 1.1f;
  
  // calculate the current
  float i1 = 0;
  float i2 = 0;
  float vdelta = V - v; 
  if (v > 2000.f) {
    i2 = (vdelta / R2);
  }
  i1 = (vdelta / R1);

  // power calculation
  float p = (v / 1000) * (i1 + i2); 

  // report to the serial line
  Serial.printf("V=%.0fmV I=%.0fmA ", v, i1 + i2);
  Serial.printf("I1=%.0f I2=%.0f P=%.0fmW\n", i1, i2, p);

  // print results to the LCD
  lcd.setCursor(0, 0); // first line
  lcd.printf("V=%.0fmV I=%.0fmA ", v, i1 + i2);
  lcd.setCursor(0, 1); // second line
  lcd.printf("I1=%.0f I2=%.0f P=%.0fmW\n", i1, i2, p);
}

platformio.ini

; PlatformIO Project Configuration File
;
;   Build options: build flags, source filter
;   Upload options: custom upload port, speed and extra flags
;   Library options: dependencies, extra library storages
;   Advanced options: extra scripting
;
; Please visit documentation for the other options and examples
; https://docs.platformio.org/page/projectconf.html

[env:wio_link]
platform = espressif8266
board = wio_link
framework = arduino

monitor_speed = 115200
upload_speed = 921600

lib_deps =
  # Using a library name
  LiquidCrystal_I2C

This project can be completed using

• Visual Studio Code
• PlatformIO IDE
• WIO Link or similar microcontroller, such as ESP32, ESP8266, Arduino