GE865: Service pin (H1) DC level requirement

6 thoughts on “GE865: Service pin (H1) DC level requirement

  1. Could you confirm the voltage level required for the Service pin (H1), please?

     

    The HW User Guide r12 does not specify the level required, but specifies that the pin should not be left unconnected if unused (Note page 16).

     

    Interpreting the following text extract from a thread – it seems that for debug purpose it should be left connected to a test pad and floatting , tied to ground to update the module via RX & TX_TRACE. As a result for unused function we can guess that it should be tied to 2V8 supply – Is that correct? Can you confirm the levels on Service pin H1 when unused, please?

     

     

    From another thread: “service pin shall be used to upgrade the module from ASC1
    (RX_TRACE, TX_TRACE). The pin shall be tied low to enable the feature only in case of a SW Update activity. It is required, for debug purpose, to be connected to a test pad on the final application.”

     

     

     

     

    1. Service pin is CMOS 2.8V, and to be able to tie it to GND, while still normally not floating an appropriate pull-up resistor must be put in place.

       

      1. Thank you for confirming that the Service pin should be connected with a pull-up resistor.

         

        Can you recommend a value for this resistor – knowing that the H/W User Guide specifies that:

         

         “In order to avoid a back powering effect it is recommended to avoid having any HIGH
        logic level signal applied to the digital pins of the GE865 when the module is powered
        off or during an ON/OFF transition.”

         

        1.  "In order to avoid a back powering effect it is recommended to avoid having any HIGH
          logic level signal applied to the digital pins of the GE865 when the module is powered
          off or during an ON/OFF transition."

           

          The datasheet is quite confusing in that aspect.

           

          This back powering effect really occurs when apply HIGH logic level to the module while it’s off, and sometimes instead of back powering, the PWRMON line also gets crazy, not reporting the correct state of the module (module is off but PWRMON goes high)

           

          Wouldn’t a pull up on these pins cause that back powering effect ?

           

          Besides the recommendations, here i leave these pins disconnected (*RESET, SERVICE, RX_AUX, TX_AUX), and everything is working fine till now…

          1. Wouldn’t a 2.8V source with shutdown help for this pourpose? Like other modules, GE863 have it internally, VAUX1?

             

  2. The advise from my colleagues is what follows, confirming Bruno Duarte’s experience:

     

    The SERVICE pin has an internal pull up resistor, so externally we
    haven’t to connect any pull up resistor; an external pull up resistor
    could modify the right pull up resistance.