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Everything Else » LCD panel speed

August 04, 2012
by eminthepooh
eminthepooh's Avatar

I'm trying to program a simple side scroller game using the AVR and LCD provided in the kit. I've read in a couple places that the HD44780 can't work too quickly and should be run under 4 MHz. During the programing of my game I've seen glitches with random characters popping up at random positions, could it be that the 14Mhz clock is too fast?

If so, can I keep the bootloader that came with my AVR and just tweak the fuses so that I can run off of the internal 8Mhz and divide it by 8 so its 1MHz? how?

Thanks,

August 07, 2012
by pcbolt
pcbolt's Avatar

Try slowing down the communication with the LCD with software first (i.e. use delays between writes), before you try the internal clock. Besides changing fuses, I believe you'd need to change the bootloader code too. Then you are talking about an outside programming device. I haven't read about the HD44780 being slow but the way the NK connect to it is via 4-bit transfers. You could try using 8-bit, or even better would be to hook-up a wire to the R/W line of the LCD and test for write "readiness". This would be faster than the standard delays built into the code.

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