I am trying to use the PR3-6 connected to a third party SBC to measure the power being used on a 12VDC circuit, but cannot seem to get valid data from the board.
The SBC recognizes the board at I2C address 0x48. I have downloaded and built the small C test program that does a single read of channel 0. The program runs without error; the correct number of bytes are written (1) and read (2).
I have a load connected as in the diagram off the product page: +12 VDC into the load (a webcam); the negative lead from the load to the #1 IP+ screw terminal; #1 IP- screw terminal connected to ground. The webcam is operational and is using about 2.5W.
The problem is that the data coming from the PR3-6 is out of the expected range and does not change when a load is connected. The data varies from about 255 to about 382 (decimal), whether there is a load or not. I get the same values on all eight channels, only one of which has a load going through it at this point
Based on the documentation, I would expect a mid-range value (about 2500) for a channel with no load, but as I say, none of the channels are reading above about 400, even the ones with no connections to their screw terminals.
I get the feeling that the test program is not actually communicating with the ADS7828, as the numbers coming out are a bit nonsensical.
I have tried different addresses for the chip, but the results are the same. Similarly, I tried different positions for the other two jumpers (I2C 5V and Pull Up), to no avail.
Any help or suggestions would be appreciated.