Axe133 4x20 oled - how fast??

[jsmanson]

I am trying to configure an axe133 using the winstar 4x20 OLED to communicate as fast as possible with my main 40x2 which is going to run at 64mhz.

I am hearing through other posts that the max speed is 4800 baud. If that is the case I need to slow down the main pic down to 32mhz as that is the fastest speed that will run 4800 baud.

So this is what I did:

40x2 runs at 64mhz, except when writing to the LCD. The routine that writes to the LCD starts with a setfreq em32, sends out data at N4800_32, then the display routine ends with a setfreq em64.

The LCD, I just insert a setfreq m32 just 'above' the "main:" routine in the 18M2 micro, I leave the default N2400 'as-is', as the setfreq m32 will double the speed anyways.

When I run this, the screen is garbled.

Can anyone suggest what I may be missing? I am running the 40x2 with an external 16mhz oscillator, the only thing I am thinking could be the problem is the ocillator might not be working correctly, hence the timings will be off.

Any other ideas or suggestions?

John

 

[nick12ab]

Setfreq em32 will still run at 64MHz because the external oscillator is 16MHz and a 4x PLL is used. The number after 'em' is ignored and is only for code readability.

It may be possible to disable the 4x PLL via registers, but I'm not aware of any method to change it to a 2x PLL, so use 16MHz internal instead.

 

[jsmanson]

Perfect, that's the issue, thanks!!

John