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5. Volt Ammeter
Uses an INA219 chip to measure current and a seperate ADS1015 ADC with potential divider onboard for potential difference. This device is capable of simultaeously measuring those quantities and plotting them against time and/or each other. Resolution of 1mA and 10mV respectively with a range of 0-3.2A and 0-18V. Data rate of ~100Hz.
| Component | Product Code | Approx Ex-VAT price | Link |
|---|---|---|---|
| Adafruit ESP Feather V2 | ADA5400 | £16.5 | Pimoroni |
| Adafruit INA219 | ADA904 | £8 | Pimoroni |
| Pimoroni ADS1015 | PIM422 | £11 | Pimoroni |
| 50mm JST SH cable | CAB1015 (Pimoroni) / 104220 (PiHut) | £1 | PiHut / Pimoroni |
| 100mm JST SH cable | 104221 (PiHut) | £1 | PiHut |
| M2.5 3x10mm screw, 4x6mm screw, 7x nuts | 103126 (PiHut) / ADA3299 | £ | PiHut |
| 4 x female banana connector | £ | ||
| 1 x 2 pin PCB screw terminal (2.54mm pitch) | £ | ||
| 500mAh LiPo battery (Optional) | BAT0003 (Pimoroni) | £6 | Pimoroni |
Note both Pimoroni and PiHut have educational discounts available that can reduce these costs further.
- Navigate to the device page on Printables and download the model files (stl) : https://www.printables.com/model/391877-diy-bluetooth-voltmeterammeter
- Slice the stl files. I have had success printing with 0.20mm 'Layer Height' and 6 Top/ 4 Bottom 'Solid Layers'
- Suggested print order is shown left to right with the example prints below:
- The INA219 sensor will need the terminal block soldering to it. The ADS1015 board does not have a STEMMA QT port - cut one end off the 100mm JST SH cable, strip the wires and solder them to the board (Red - 3-5V / Blue - SDA / Yellow - SCL / Black - GND) - see photo. The 2.54mm pitch terminal will need to be soldered to the A0 and A1 pins - the legs need a bit of forcing to make the tight pitch of the board.
- Using two 6mm screws (and nuts) attach first the INA219 sensor to the PCB tray. Use another one 6mm screw (and nut) in the left hole to attach the ADS1015 sensor board as well - note the orientation in the photo below
- Insert the 50mm STEMMA QT cable into the INA219 sensor (as above). Also insert your soldered 100mm STEMMA QT cable into the other INA219 port
- Using one 6mm screw (and nut) attach the ESP32 board to the tray (lower right corner) and insert the STEMMA QT cable from the INA219 sensor
- Solder 50mm lengths of wires to the ends of your 4mm banana connectors and screw them into the case
- Turn the case over and place three nuts into the recessed holes. Then place the case face up on a flat surface
- If using a battery now is the time to attach it. Ensure the polarity is correct using the information printed on the PCB silkscreen to guide.
- Place the battery into the case and lay the PCB tray over it with the three remaining mounting holes lining up with the three case holes. Use the three 10mm screws to attach the PCB tray to the case. You may need to manipulate the battery wires - ensure they do not lie between the battery and the PCB tray.
- The left two banana connectors are for the INA219 (Ammeter) - red -> Vin+ / black -> Vin-. The right two connectors for the ADS1015 (Voltmeter) - red -> A0 (left in photo), black -> A1 (right in photo)
- Snap fit the lid and the build is complete
Ensure you have the 'Adafruit INA219', 'Adafruit ADS1X15', 'phyphox BLE' and 'Adafruit NeoPixel' libraries installed (Library Manager)
You must also have ESP32 board definitions installed (see wiki entry for guidance)
- Navigate to the Ammeter-Voltmeter folder in the main code - https://github.com/RGill-1/Bluetooth-Science-Sensors/tree/main/Ammeter-Voltmeter
- Use the Arduino IDE to upload the latest .ino file onto the board.
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In phyphox use the 'Add experiment for Bluetooth device' functionality to get the experiment off the device. Make sure to click 'save to collection' when prompted
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Start collecting data by pressing the play button at the top (the first time you do this you may need to reconnect to the device - click 'try again' if prompted)
