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HP Forum Archive 18

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HP-20B dev: LCD
Message #1 Posted by Scott Newell on 22 July 2008, 12:48 a.m.

I think I've nailed down everything but the graphic section of the LCD now. Rather than try and find the pattern, I went with the brute force lookup table approach. It's a start--this is ARM code running from the internal SRAM:

And yes, I remembered to run in little endian mode tonight--the port C assignments make a lot more sense now.

PC0         Keypad column 0
PC1         Keypad column 1
PC2         Keypad column 2
PC3         Keypad column 3
PC4         Keypad column 4
PC5         Keypad column 5
PC6         Keypad column 6
PC7         R18 (drives transistor near '232 level shifter)
PC8         ?
PC9         ?
PC10        On key
PC11        Keypad row 0
PC12        Keypad row 1
PC13        Keypad row 2
PC14        Keypad row 3
PC15        Keypad row 4
PC16        J35 (pgm RX connector)
PC17        J33 (pgm TX connector)
PC18        J8-7
PC19        J8-9
PC20        J8-8
PC21        J8-6
PC22        J8-2
PC23        ?
PC24        ?
PC25        ?
PC26        Keypad row 5
PC27        J8-4
PC28        J8-5
PC29        J8-3

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