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EP9307  backlight off problem

Jayaram K
Note: This was originally posted on 14th July 2011 at http://forums.arm.com

I have a device with touch screen LCD and backlight using ep9307 controller of ARM processor. The problem is that we need to completely switch off the backlight so as to make the screen look dead.

Being a newbie in this field, I have no idea how to do that. After studying the schematics and user guide I came to know Brightness control register named as BRIGHT.But I have no idea how to write to that register.

I need to know how to do that. Can anyone please help.
Parents
  • Note: This was originally posted on 15th July 2011 at http://forums.arm.com

    Hi,
      The details are as follows
      1.C++ is the programming language used .Drivers are written in 'C' .
      2.Operating system ---Red hat  Linux
      I have been  working on the application layer  of the embedded system . I have no idea how the drivers were written for the hardware .
    Current requirement is backlight should be switched off  and on  . 
    I have till now studied through the data sheet and user guide of EP9307-CRZ controller. From that I found out that there is a 32 bit brightness control register.  16 bits of the register are reserved while reading. 8 bits are for CNT and 8 bits for CMP. Now for various values of CNT and CMP the brightness is toggled. If the both CNT and CMP is reset 0% brightness is achieved.
    Also I found out in the circuit diagram of EP9307 there is a BRIGHT pin on which PWM (Pulse width Modulation) waveform helps to control the brightness.

    So far the investigation have been theoretical and nothing practical has been tried out. The problems are:

    1. How to access to the brightness control register and write to it?
    2. Is there any library functions to access it?
    3. IS BRIGHT pin controlled by brightness control register?

    Hope my question are clear.
Reply
  • Note: This was originally posted on 15th July 2011 at http://forums.arm.com

    Hi,
      The details are as follows
      1.C++ is the programming language used .Drivers are written in 'C' .
      2.Operating system ---Red hat  Linux
      I have been  working on the application layer  of the embedded system . I have no idea how the drivers were written for the hardware .
    Current requirement is backlight should be switched off  and on  . 
    I have till now studied through the data sheet and user guide of EP9307-CRZ controller. From that I found out that there is a 32 bit brightness control register.  16 bits of the register are reserved while reading. 8 bits are for CNT and 8 bits for CMP. Now for various values of CNT and CMP the brightness is toggled. If the both CNT and CMP is reset 0% brightness is achieved.
    Also I found out in the circuit diagram of EP9307 there is a BRIGHT pin on which PWM (Pulse width Modulation) waveform helps to control the brightness.

    So far the investigation have been theoretical and nothing practical has been tried out. The problems are:

    1. How to access to the brightness control register and write to it?
    2. Is there any library functions to access it?
    3. IS BRIGHT pin controlled by brightness control register?

    Hope my question are clear.
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