The Dual Channel Voltage and Current Monitor project was created as I needed a way to look at the voltage and current going into an Adafruit Powerboost 1000c module and through the soft switch circuit that I built from Mosaic Industries Raspberry Pi ON/OFF Power Controller. I wanted to be able to monitor the voltage and current coming out of the controller and going into the Raspberry Pi.
The project is based on the Adafruit INA219 High Side DC Current Sensor Breakout and a Raspberry Pi Pico. The Raspberry Pi Pico is a bit overkill for this project, but I have a few on hand so that is what I choose to use.
- Adafruit INA219 High Side DC Current Sensor Breakout – 26V ±3.2A Max – STEMMA QT
NOTE: I had the older version of these on hand without the STEMMA QT connecters.
- Adafruit Monochrome 1.3″ 128×64 OLED graphic display – STEMMA QT / Qwiic
NOTE: I had the older version of these on hand without the STEMMA QT connecter.
- Raspberry Pi Pico
- Adafruit Panel Mount Extension USB Cable – Micro B Male to Micro B Female
- Adafruit Panel Mount USB Cable – B Female to Mini-B Male
- Adafruit Panel Mount USB Cable – A Male to A Female
NOTE: I had some similar ones on hand that plug into PC Motherboards, which I used instead.
- Adafruit Adafruit Perma-Proto Half-sized Breadboard PCB – Single
One was used for the Raspberry Pi Pico and the other for the 2 INA219 breakout boards.
- Radio Shack 10A/250V AC Binding Posts (2-Pack)
QTY: 4 (4 packs for a total 8 binding posts with 4 red and 4 black)
- Radio Shack Project Enclosure Box – 8 x 6 x 3″ Catalog №: 2701809
- Glowforge Draftboard™ 12 x 20″
Used for inside front panel and mounting plate for Perma-Proto boards
- Glowforge Clear Acrylic 12 x 20 x 1/8″
Used for outside front panel
- Miscellaneous mounting hardware. Screws, nuts, and binding posts.
- Heat Shrink Tubing
- Hookup Wire
Next Steps/Going Further
The data transfer rate is extremely slow. It is good enough for what is being done here but it would be nice to capture more data points over the same period. Right now, the rate is about one set of measurements per minute. (It takes about 1.2 seconds to send one set of measurements.) One way to speed this up would be to move away from JSON and sending tab delimited data. I may create another version of the Raspberry Pi Pico and Windows software to send delimited data and see if there is an improvement. I would expect to get 4 to 5 times as many measurements in the same amount of time. It still is not very fast, but it would be an improvement.
- TaW had a good reply to SunAwtCanvas’s question regarding Chart Auto Scroll (Oscilloscope Effect). While I did not use the code verbatim, it did point me in the right direction.