LCD HSync and VSync Polarity

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1

I want to connect a Sharp LCD TFT display to the LCD port.
Unfortunately, the display requires active-low (or negative-going)
VSync and HSync signals for proper synchronisation. Can the VSync and
HSync signals be switched to reverse polarity by reconfiguring the
OMAP3530?

Is there a guide for connecting displays to the Beagle Board?

Thanks, Christian

2

The polarity of the sync signals can be changed in SW. However, as you need to do a level shift from 1.8B to the voltage required by the display, then you can do that in HW by using an inverter. There is no formal guide for connecting LCD displays as they are all different and unique in their requirements.

Basic requirements are:

  1. All signals are 1.8V, so you will need to level shift the signals.
  2. You will need to supply the required voltages from the supplied 5V as required by the display. You need ot make sure the 5V supply you use can handle it.
  3. You will need to supply the backlight control voltage, brightness, and on/off control.
  4. If a touchscreen is used, you will also need to supply the Touchscreen controller. If you use I2C, then that is supplied on the LCD expansion headers. Otherwise you will need to also use the full expansion header to access those signals.
  5. Depending on the bit resolution of the display, (16, 18, or less) the unused LCD pins can be used as GPIO. If you are full 24b, then you will need to use the expansion header to access those signals.
  6. There are PWM signals on the expansion header for backlight control.

Gerald