INA219 Current Monitor

// TK119 INA219 wiring
//
//   TK119 GND  -> Arduino GND
//   TK119 3V3  -> Arduino 5V (an Uno's logic is 5 V, so the bus is 5 V)
//   TK119 SCL  -> Arduino A5     (third pin on the board)
//   TK119 SDA  -> Arduino A4     (fourth pin)
//   POWER + / - -> the supply you want to measure
//   LOAD  + / - -> the load
//
// Arduino IDE: Sketch > Include Library > Manage Libraries, then install
// "Adafruit INA219". No board-specific Tools settings.

#include <Wire.h>
#include <Adafruit_INA219.h>

// 0x40 with nothing soldered. 0x41, 0x44 or 0x45 if you bridged A0 or A1.
Adafruit_INA219 ina219(0x40);

void setup() {
  Serial.begin(9600);
  if (!ina219.begin()) {
    Serial.println("no INA219 at 0x40 - check SCL and SDA, they are the other way round here");
    while (1) delay(10);
  }
  // The library's default is the 32 V, 2 A calibration. Say which range you
  // want: the narrower ones are more accurate, not merely smaller.
  ina219.setCalibration_32V_2A();
  Serial.println("bus V\tshunt mV\tcurrent mA\tpower mW");
}

void loop() {
  float bus   = ina219.getBusVoltage_V();     // measured, at the LOAD + screw
  float shunt = ina219.getShuntVoltage_mV();  // measured, across the resistor
  float mA    = ina219.getCurrent_mA();       // shunt voltage / 0.1 ohm
  float mW    = ina219.getPower_mW();         // from the chip's power register

  Serial.print(bus, 3);   Serial.print('\t');
  Serial.print(shunt, 2); Serial.print('\t');
  Serial.print(mA, 1);    Serial.print('\t');
  Serial.println(mW, 1);
  delay(500);
}

# TK119 INA219 wiring
#
#   TK119 GND  -> Pico GND
#   TK119 3V3  -> Pico 3V3
#   TK119 SCL  -> Pico GPIO 1    (third pin on the board)
#   TK119 SDA  -> Pico GPIO 0    (fourth pin)
#   POWER + / - -> the supply you want to measure
#   LOAD  + / - -> the load
#
# No driver library needed: three registers is less code than installing one.

from machine import I2C, Pin
import time, struct

ADDR = 0x40          # 0x41, 0x44 or 0x45 if you bridged A0 or A1
SHUNT_OHMS = 0.1     # the resistor fitted on this board

i2c = I2C(0, scl=Pin(1), sda=Pin(0), freq=100_000)

# Config register: 32 V bus range, gain /8 (+-320 mV), 12-bit, continuous.
i2c.writeto_mem(ADDR, 0x00, struct.pack(">H", 0x399F))

def signed(v):
    return v - 65536 if v & 0x8000 else v

while True:
    shunt_raw = signed(struct.unpack(">H", i2c.readfrom_mem(ADDR, 0x01, 2))[0])
    bus_raw   = struct.unpack(">H", i2c.readfrom_mem(ADDR, 0x02, 2))[0]

    shunt_mv = shunt_raw * 0.01        # one count is 10 uV
    bus_v    = (bus_raw >> 3) * 0.004  # three flag bits, then 4 mV per count
    amps     = shunt_mv / 1000 / SHUNT_OHMS

    print("{:.3f} V  {:.2f} mV  {:.1f} mA  {:.0f} mW".format(
        bus_v, shunt_mv, amps * 1000, bus_v * amps * 1000))
    time.sleep(0.5)