I have a wierd problem that I can't figure out.
I have a T7 and a T4 being controlled by a Python script .
I can communicate just fine with these devices and I"m running a python script on the Pi. The issue comes with an i2c sensor, specifically a Sensirion SDP810-500. For some reason on the T7, this sensor won't register (no acks) unless I run the program first with that sensor as the only one in my list. That seems to jolt it enough for it to work, and then I can add the other sensors back including those hooked up to the T4 and it will work. That is until I power cycle the T7 and then again I need to 'reset' by modifying the program to be only the single sensor.
I thought it might be the fact the raspberry pi was providing the power, but I switched the T7 with the T4 and the problem occured again on the T7 connected sensor. I assume this has something to do with power, but I can't be sure due to my lack of knowledge of such things.
Any help is appreciated!
Other notes:
- The T4 doesn't seem to have the same issue.
- Other i2c sensors don't seem to have the same issue.
- If I swap an i2c from the T7 to the T4 they then start to work.
- I'm using the labjack LJTick-LVDigitalIO for all the i2c sensors ensuring 3.5 volts power and signal line
.png%3Fitok=PHGBxf6M "EEV Blog Reviews LabJack T7-Pro & Software Tools")
.jpg%3Fitok=B1YcuDFK)
.png%3Fitok=Ybt-OlgU "LabJack + JEDI One Can Create a Powerful Distributed DAQ Ecosystem")
The T7 requires a bit more power than the T4, so if you are close to the supply limit you might have just enough headroom with the T4 but not enough with the T7. The following page has our power specifications:
https://labjack.com/support/datasheets/t-series/appendix-a-5
Do you see the issue if you just have two sensors connected or does it only become an issue after adding a few?
To ensure the device is getting adequate power, one thing you could try is connecting the T7 to the Pi via Ethernet and use a USB wall adapter to power the T7.