Interfase trouble with the raspberry pi 3 (Digital inputs)



  • I am currently trying to find the technical specifications of the UniPi 1.1. in order to see how the digital input works. Because I already have the relays working however the digital inputs are still a problem. I can see that a optocoupler is used however I can not find the corresponding datasheet (Could you provide that for me?) and I am not sure if I need to do something with a pull up/down resistance on the Raspberry side because I can not find the circuit design of the digital input (Could somebody provide that for me? I can already see that there is a led, resistance, optocoupler, Something..... ,Raspberry Pi 3 input, but I simply do not know the exact layout which makes it difficult to trouble shoot using a oscilloscope). Currently I can read 3 of the 12 inputs (I1, I8 and I9) and it seems that a active input voltage gives a low input on the raspberry pi (is this correct?). This would be strange because all the other inputs (the ones that are not working) are low even trough I connected them to ground (So then I would expect them to be high).

    With kind regards,
    Jelle


  • administrators

    @jelle You have to enable internal pull-up resistor for the GPIOs and set them as inputs



  • Ok, I have one other question because the ground for the analog signals is clearly marked but what is the ground for the digital input? Is that the same as the analog ground or is that one of the grounds elsewhere on the board?


  • administrators

    @jelle the levels can be different if you configure the jumpers to use different power supply, if you are using the onboard 12, then the GNDs are on the same level