Monday, June 19, 2023

Drawing on the LCD screen to test functions I need - part 10

CLEANING UP BITMAPS AND PLACEMENTS

I stopped fooling around with 'user friendly' programs that won't let me control all the parameters of the bitmap being generated. GIMP to the rescue where I was able to rebuild my arrows, at the desired smaller size, with the added benefit that I could recolor it cyan to better match the selection toggle button. 

The relative placement of the two arrows and the toggle button were tweaked until I was happy with the interface. The starting point before the failed attempt to shrink the arrows is shown below, along with the UI operating after the bitmaps were mangled. 

UI with oversize arrow bitmaps

UI with mangled bitmaps

After my work with GIMP and a test, I did some adjustments to end up with an acceptable user interface screen. The UI shows 13 file names of a larger number on the SD card, with the first entry highlighted but not selected. 

DOCUMENTATION SAYS LCD MODULE TESTED UP TO 60MHZ BUT 50 FAILED FOR ME

I tried to bump up the speed of the SPI link to the LCD controller chip since the documentation for the module asserted that it had been tested up to 60MHz. When I set it at 50MHz in my setup, it failed. This may be due to poor signal quality since I was using cheap jumpers. In any case, I switched back to 25MHz which seems to work reliably for the screen. 

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