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SGC or Serial environnement random Issue

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  • SGC or Serial environnement random Issue

    Hello we have 2 type of screen in our devices :
    - SGC PMMC : uLCD-43PTSGC-R22 working @9600 bauds until 01/08/2017, we have put this PMMC in new devices.
    - PIC : PMMC : uLCD-43PT-R44 + serial environnement. working @200k bauds

    We have about 350 devices by our differents customers all around the world

    We observe random issues as visible in the video :
    some devices are more subject, especially R22 pmmc but also append on the R44

    Do you have any idea where to look. What can cause this kind of behaviour ?

    Note : we wait the ACK for every transaction. When it starts to have issue, we get no response, or error response.

    Sometime i suppose that the device restarts, but how to monitor it ?

  • #2
    Hello Thomas,

    Welcome to the forum.

    Please be reminded that the SGC PMMC as it already obsolete and is no longer supported. Thus it is advisable to upgrade to GFX PMMC.

    Also, can I confirm the exact number of devices loaded with SGC PmmC and those loaded with GFX PMMC? Were these devices purchased separately or do they belong to a single purchase?

    As we have not encountered the issue yet and for further analysis, I would like to ask for logic analyzer data showing the communication between the display and the host at the time of the occurrence of the issue. Also, a general description of your setup (what the host MCU is, how the system is being powered, etc) would be helpful.

    Thank you and Best Regards,


    • #3

      thank you for quick reply.

      unfortunately I don't have exact count. But i would say about 200 devices with SGC PMMC and 150 with GFX.
      Also, we bought the screens along with the production : orders from 20-30 pces each time. (through Radiospares or sometimes in the past on your website)

      I can try to logic analyse, but it is not easy as this can produce in a random time.

      The host is an AVR32 microcontrole with embedded freeRTOS programmed in C.

      We communicate and power the board through the 30 pins connector.

      the screen is powered by a dedicated boost from a single cell li-ion battery. See scheme bellow.

      Also it is complicated to update, as it requires to get the device, open it ....

      Occurence is about : 10 devices in the last 6 months. but sometimes, the user just turns off and on without saying anything.

      So 3 additionnal questions :
      - can we get the serial number using serial interface ?
      - how to detect the device has restart ?
      - is it possible to update the PMMC directly with our microcontroller (without your PMMC loader).

      Kind regards


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      • #4
        Hello again Thomas,

        Thank you for your message. The issue is unique to your setup. Can you also please replicate the issue using a known stable power supply - a bench power supply perhaps - instead of a battery? This way, we can narrow down the root cause.

        Please see below my answers to your questions.

        “can we get the serial number using serial interface? ”
        Unfortunately, there is no serial information embedded in the memory of the processor. However, if you want, you could embed custom ID information into the uSD card or the flash memory prior to shipping your end-product.

        “how to detect the device has restart? ”
        I have two suggestions for this:
        1. You can modify the SPE program so that the display will send out a unique message (the serial number for example) to the serial port after powering up. The host controller could then use this as a notification that the display module has restarted. You can check the 4DGL code for the SPE program by following steps 1 and 2 of this post:
        2. The host can send a known value to the display module then query this value intermittently. If this value has changed inadvertently, then this could mean that the display module has restarted. For this approach, you can use the set and get image parameters commands, or the put and get pixel commands.

        Let me know if you need further help with any of the options described above.

        “is it possible to update the PMMC directly with our microcontroller (without your PMMC loader). ”
        Yes, this is possible. You would need to implement the PMMC uploading protocol on your host microcontroller. The protocol is available under an NDA. If you wish to proceed, please open a ticket at

        Best Regards,