The INA219 Serial Ammeter Project
Hobbyist USB Supply Current Monitor Tool ...

Compatible with the FTDI serial cable and
monitors current using the INA219.

The ATtiny microcontoller monitors current using I2C interface to the INA219 current monitor and reports the measurement to the serial port. This plugs into the FTDI breakout cable to report current draw from your USB supplied project.

  • Programmable ATtiny85A PDIP8
  • Based on INA219 current sensor Datasheet
  • USB +5V supply
  • Outputs current in mA
  • 9600 baudrate

See our Raspberry Programmer page on how we programmed the ATtiny85 using the Raspberry Pi, thanks to alot of resources online.

Second Prototype Built
2nd September 2017
  A second prototype has been built and works well. It includes pull-ups and logic level translation, as well as a LED to indicate when powered and when something connected is consuming some current.
Bit Banging
27th June 2017
  Our test program successfully bit bangs characters through a FTDI USB to UART cable. The cable supplies +5V to power the circuit. Some logic level translation is needed to protect the FTDI +3.3V pins.
Raspberry Pi Programmer
30th May 2017
  We have setup a Raspberry Pi to program the ATtiny85A following some online guides. We have put together a howto here.
Prototype Built
27th May 2017
  The first prototype has been assembled.
PCB Design
29th April 2017
  The PCB has been drawn using the PDIP8 ATtiny85 so that it can be removed and programmed with Arduino code. A crystal is fitted incase issues are encountered with baudrate reliability.
17th April 2017
  Concept developed and draft schematic designed.


» Softlatch Project
   Power latch with software power-off function
» INA219 Serial Project
   Serial ammeter for project USB supply
» AuraBean Project
   Probability and sensitivity research tool
» AuraBean II Project
   Web-enabled probability and sensitivity research tool
» Guessology Games
   Random browser-based guessing games


» Raspberry Pi Programmer
   Programs ATTiny85 microcontrollers
» Pycom WiPy Setup
   Setup and program the WyPi

© 2020 Cedric Joyce