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Correct serial for direct connect FFC

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  • Correct serial for direct connect FFC

    I have experience with early 4D modules, so in general know what I am doing.

    I have ordered a gen4-uLCD-24PT and am designing a PCB that will interface (using serial) to the display via the 30pin FFC cable.

    I'll unplug the FFC if I need to update firmware on the display else it will be connected to the application (using a PIC) on my PCB.

    I have the various schematics etc but want to make absolutely sure things are correct. I'll be connecting to RX, TX, 5V, Gnd and Rst. Hence the following questions:

    1. I assume I should be using RX0/TX0 (pins 23/24) rather than RX1/TX1?

    2. I have seen confusing info on the forum that suggests data OUT of the display is labelled Rx rather than Tx. Could someone please confirm which of RX0 or TX0 is the pin that TRANSMITS data from the display module to the outside world?

    Many thanks,

  • #2
    Hi David

    Confusion might happen with some people as TX joins to RX and RX to TX, and so on our 5 way cables we have on older products, one end of the cable has RX on the same wire the other end has TX, as you have to cross them at some point. It comes down to a matter of perspective as to what device you are looking at relative to - one method doesn't suit all people unfortunately.

    If you look in the datasheet you will find the schematic of the module at the end, that might help confirm to you 100% what you are looking for, as you can trace it all the way back to the processor.

    However that said, RX0 (Receive) on the Picaso goes to pin 23 of the 30-way FFC cable, and TX0 (Transmit) on the Picaso goes to pin 24 of the 30-way FFC cable.
    You can use RX1/TX1 if you wish, and configure the display to use that, while retaining RX0/TX0 for programming - then you dont have to unplug anything when you program the display, if you have a programming connection of some kind on your PCB you are making. Just an idea.

    Hope that helps



    • #3
      Hello James,
      Very helpful- thank you!
      Best Regards,