Re: "White Screen" Troubleshooting Tips for DSO138
Posted: Wed Sep 23, 2015 9:33 am
The problem with "LCD signal" is that it is quite complicated over many wires. In normal cases, you would be developing software in parallel with debugging the hardware. That complicates things: The hardware guy says it must be a software problem and the other way around.
In this case, you have a big advantage: you KNOW the software works. And Secondly you KNOW that the hardware design is good.
The chip on the LCD module is "smart" in that it shows a "known pattern" when it has proper power but has not yet received any data from the CPU. In this case that's the white screen. (for a HD44780 controlled 16x2 character LCD its a row of blocks on the first line and a blank second line. For the displays on the Airbus A320, it's a lissajous pattern).
So: knowing that the CPU runs its software (it blinks the leds, so it must be running!) and that it is TRYING to display stuff on the LCD, you'll have to think and measure to deduce where the problem lies.
In this case, you have a big advantage: you KNOW the software works. And Secondly you KNOW that the hardware design is good.
The chip on the LCD module is "smart" in that it shows a "known pattern" when it has proper power but has not yet received any data from the CPU. In this case that's the white screen. (for a HD44780 controlled 16x2 character LCD its a row of blocks on the first line and a blank second line. For the displays on the Airbus A320, it's a lissajous pattern).
So: knowing that the CPU runs its software (it blinks the leds, so it must be running!) and that it is TRYING to display stuff on the LCD, you'll have to think and measure to deduce where the problem lies.