In order to fix this issue I changed my pull-up resistors to 10K instead of 100K. In my case the LCD panel pulled the signals lower than the required upper voltage threshold and so my processor would not boot when the LCD panel was plugged in. As the application note states in the red box below the description the weak pullups/pulldowns might effect your design.
This Octavo Application Note explains it better than I could. The AM3355x can connect up to a 16-bit or 24-bit LCD screen using the following signals:īesides driving the LCD panel, the LCD data signals are also used to configure the order in which the processor attempts to boot from devices. There were already reference designs online as well as documentation within the kernel describing how everything hooks up but due to hardware design caveates and mistakes on my part and quirks in the kernel boot process I didn’t understand it took a long time to get the LCD up and running. Out of all things I thought that it would not have been this difficult. One aspect of the board that I had some trouble with was bringing up the Newhaven 5inch LCD Screen to work with the parallel LCD interface.
I built a new board called guppy-buddy that looks like a game console using the Octavosystems OSD335X-SM which made the design process must simpler than if I attempted to layout an entire processor, PMIC and RAM as well as everything else I wanted to do.
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