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Power Down Sequence Warning Explained

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  • #16


    Thanks Steve, I was missing that information. Now it is clear.
    Walter

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    • #17


      I presume that every time I program the display from the Workshop, I am forcing a reset thereby potentially damaging the display? Or does the Workshop power down the display before resetting?

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      • #18


        I presume that every time I program the display from the Workshop, I am forcing a reset thereby potentially damaging the display? Or does the Workshop power down the display before resetting?

        Bumping. This question deserves an answer. 4D Systems?

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        • #19


          Reseting the display does not involve a 'power down'.

          'Power down' is just that, removal of power.
          Mark

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          • #20


            When a download takes place, the display is powered down during its re-initialization sequence so no harm will result.
            Regards,
            Dave

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            • #21


              Thanks Both. Good to hear.

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              • #22


                Hello,

                I would like to know if the Goldelox-gfx processor can be put in power save mode while the display is not being used. Can this be accomplished through RS232 communication? Does Picasso support power down?

                Regards,
                Sriram.
                Sriram Karunagaran

                Comment


                • #23


                  Hi,
                  does anybody else have a full orange screen when you enter contrast 0?
                  Although my code needs a bit cleaning, if im not mistaken, when the OLED (µOLED-32028-PMD3T) executes the contrast 0 command, it goes full orange (im sure for that part) and then it goes black displaying the ppmc version on top of the screen (right like when you flash the ppmc "1.08 ok")

                  Also, i have the orange screen right on boot up! This appeared after a ppmc upgrade (dont remember which one). Is it possible to keep it black?

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                  • #24


                    I just bought a 32028-P1T display and the above mentioned problems (orange screen) with the booting and CONTRAST 0 arent there. IT works perfectly.
                    The problem must be in the PMD3T ppmc.

                    Attila, a bug fix please? I have two of those PMD3T's and im afraid to use them since i cannot turn them off the proper way. Thanks

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                    • #25


                      Hi,
                      I tried the uOLED 32028 PMD3T setting the screen to 9 different contrasts and eventually to contrast 0, the low power mode, and there were no problems.

                      You may have old function files in your workshop IDE causing the problem. The best option is to remove the current workshop, download the latest version from internet and install it.. Don't forget to replace the new 4DGLworkshop.tkn file after installation.

                      Cheers
                      Bilal

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                      • #26


                        Weird! I tried the whole programming thing (ppmc too) on a fresh install on a new computer with 4DGLworkshop.tkn file replaced. And i still get the orange screen... I will try this on my other PMD3T i have (never used it before) and i will post what i get.
                        Is there any chance that i have a somewhat faulty display?

                        Thanks

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                        • #27


                          Ok.. Tested the second PMD3T that i have. It doesnt appear to have this problem.
                          So it all comes down to that specific display. I reloaded the latest ppmc but no change. I still get the orange screen on boot and on contrast 0!
                          Is there a solution for it? Or do i have to send it back? What is procedure for RMA?

                          Thanks

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                          • #28


                            In order to proceed with the warranty and repair, you need to get back to your place of purchase with the invoice details. They will be able to assist. The product is covered for three months warranty.

                            Regards
                            Bilal

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                            • #29


                              Hmm, so far I came up with the following for mains-fed or other high-voltage powered device design:

                              Stage 1: an MCU pin is connected to the high voltage (8-12v or a bit more, depends on the critical brownout) rail or the input which is reverse-isolated with a diode used to lock off any reverse feed from the MCU supply via a current-limiting resistor to ensure the internal diodes nor the supply inrush current failure will occure and a decoupling capacitor, an internal/external pullup is necessary in order to exclude any self-discharge effects and resulting false-triggering. Whenever the voltage gets lower then the initial one more then the by the MCU Vcc-to-low threshold, the MCU should be programmed to generate an interrupt that causes a proper shotdown sequence, including LCD routines.

                              Stage 2. A passive optocoupler should be installed between the MCU RESET-triggering pin and LCD RESET input, while the LCD RESET pulldown must be installed. The coupler's LED should be connected between two different reference rails with a proper bypass, so that whenever the input voltage gets below the reference one the reset is initiated by disconnecting the pin leaving it only grounded via the pull-down resistor.

                              Wonder if it helps.

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                              • #30


                                Hi. I'm a newbie regarding this type of display. I'm looking at using the µOLED-32028-P1T(SGC)for the "front-panel" UI in a "network appliance" type box we're planning to build. This would normally be run 24/7 but can be switched off at any time. There is no facility for an operator to shutdown the system in advance. From reading this thread, it sounds like this would be a problem.

                                The display module would be driven by an SBC running Linux and it would not be practical to supply backup-power to it to be able to send shutdown commands to the display.

                                If we use a large cap to hold up +5V to the display for sufficient time, is there any electronic solution, e. g. asserting the RESET pin on the initial power-cutoff, to mitigate the problem?

                                I do understand that this problem is not limited to 4D products but it still could prevent us from using this technology.

                                Thanks in advance for clearification.

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