The most interesting part to deal was the hardware. Below you can see an old prototype board, which includes a Raspberry Pi, two custom boards for ADC, sensor connectors and voltage dividers. In the middle - a small board to supply a power. It has real-time input voltage monitoring: on 7.5V - the Data Logger start making warning sounds, on 7.0 V - automatic shutdown. Two power supplies: AC-DC external, and internal pack batteries. Also the embedded ORing controller makes a smooth transition between battery and external power supply.
The boards has been designed and implemented by Boris Shogan, my old friend and awesome Electronics Engineer. It took a noticeable amount of collaborative work in our spare time and midnight oil burnt to make this happen. But it was a plenty of fun.
Since we need 16 ports total, the natural choice was to take two MCP3008 8-Channel 10-Bit ADC with SPI interface, and have it on two standalone boards (a compact 16-port single board which hosts both ADC is also available).
Originally we had it working on Raspberry Pi Model B (512 MB RAM), and later used the Model B+. We did not tried the Raspberry Pi 2, it was released just a few days ago.
Below is the IV-board for Currency and Voltage. The low-side external Shunt or Sense resistors are plugged to the blue connectors:
Currently this types of Shunt and Sense resistors are supported by default, other types can be easily added:
- Shunt 500A 50mV
- Shunt 300A 50mV
- Shunt 100A 100mV
- Shunt 100A 50mV
- Shunt 10A 100mV
- Shunt 2A 100mV
- Sense R=0.1 15A
- Sense R=0.1 20A
- Sense R=0.25 14A
See below the image of the complete product in the box. We have been given the enclosure, and this Customer asked us to make a table-top version, so here it is. Meantime we are working on a smaller "portable" version. Stay tuned.
Feel free to get back to me if you would like to get more details about the system, get a copy of software, or customized version for your needs. You can also purchase the assembled ADC boards or DIY kits.