Andres Mata

Can't get the "VGALiquidCrystal" library examples to work

4 posts in this topic

Hi All,

I just got my new Papilio Pro and I was trying the examples from DesignLab. I've been playing around with different examples (Audio, VGA, etc.) and they work fine. But when I run any of the VGALiquidCrystal examples thye are just displaying two rows of green squares but no text in there.

The following screenshot (LCD_Demo.jpg) shows the results I get from the "LCD_Demo" example.

The VGA demos work fine (see screenshot - VGAHelloWorld.jpg)

Just fyi, I'm not using any Wing, I'm just connecting 6 pins in the CH Wing2 port to the VGA cable (V-SYNC, H-SYNC, R, G, B, GND) as in the screenshot - DirectPinout.jpg.

I am wondering if I am missing anything here. Do I require to connect anything else? Working with a real Liquid Crystal display needs to connect a couple of signals (rs, enable, data, etc.) but is it also necessary in this modified version? If not, what do the pins in the VGALiquidCrystal() call mean?

Regards,

Andres

VGAHelloWorld.jpg

LCD_Demo.jpg

DirectPinout.jpg

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Hello Andres,

You are most likely missing the Character Map which needs to be connected to a Wishbone slot in your circuit. The following code defines which Wishbone Slot it should be connected to:

VGA.begin(VGAWISHBONESLOT(9),CHARMAPWISHBONESLOT(10));

Jack.

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This is what the example LCD_Demo's circuit looks like:

Char Map.png

You need to make sure that the circuit you are using has the VGA Char Map included. You should be able to just load the circuit for the LCD_Demo to your board, as long as your VGA pinouts match what a VGA Wing connected to CH would be.

Jack.

 

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Ok, I know what's happening: I just wired one bit per RGB channel (like the VGA wing v1.0) but the LED library needs both bits per channel. As soon as I fed the second bit signal to the RGB channels the letters showed up.

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