14 Replies Latest reply on Jul 25, 2017 8:28 AM by francisco.vaz

    Raspberry Pi 7'' Touchscreen Display not powering on after energy failure

    francisco.vaz

      I have recently bough this display Raspberry Pi 7'' Touchscreen Display and got it to work just fine. The touchscreen works, the image looks great and i can control it with the Python module rpi-backlight.

       

      However I stumbled upon a problem that haven't been able to solve so far.

       

      I'm setting up a kiosk that contains this display, a raspberry pi, a 3g modem and a ups (uninterruptible power supply). The ups module is used to power the raspberry and the 3g modem so that on a power failure, the kiosk can perform some operations, send some data through the 3g connection and perform an orderly shutdown. In case of a short (in time) power failure, the UPS module is smart enough not to shutdown the system.

       

      The problem that I'm facing is that on a power failure as the monitor is not connected to the UPS, it will shutdown but when the power returns the monitor will not turn on again. The screen stays blank as in no image, no power, no backlight. To make the monitor work again I have to turn of the UPS system, power off the raspberry, power the display, and then power it on all again. If someone has a monitor like this it can replicate this problem by simply powering the monitor off and on again keeping the raspberry on.

       

      After spending some time trying to solve this problem I learned that this monitor can receive I2C commands, however I been unable so far to find out the command codes and/or how to send it a "power on" command if it even exists.

      The Python module rpi-backligh as the functionality to turn the monitor on and off which works great at start, but won't do anything after the monitor shutting down due to a power failure.

       

      My setup is:

      Raspberry Pi 3 Model B v1.2

      Raspberry Pi 7'' Touchscreen Display

      RPI SIM800 GSM/GPRS ADD-ON V2.0

      UPS PIco HV3.0 - Uninterruptible Power Supply & I2C Control HAT

       

      For OS I'm running Ubuntu MATE 16.04.

      The OS is fully updated (sudo apt-get update, sudo apt-get dist-upgrade) as the raspberry firmware (rpi-update).

       

      Does anyone have any idea of how to overcome this problem? Or a list of the I2C commands that this monitor can receive?