Charles Wigelsworth

SPI / LCD Bug?

Discussion created by Charles Wigelsworth on Apr 10, 2010
Latest reply on Apr 16, 2010 by bigmac

I posted before regarding the SPI / LCD interfacing, but I have that working now. I have run into a curious issue however.

 

If I run the code from CodeWarrior debug via Multilink, the LCD works as it should, instructions and commands work using the USB to debug/power it. If I disconnect the USB and add an external power source and power up (jumper pin on mcu project board to pwr_sel), the 9S12C32 and LCD will power up as normal, but the LCD will no longer execute. I have also verified that the 595 shift register is no longer receiving the MOSI inputs from the SPIDR. I have a significantly large enough delay prior to execution of the code to allow for powering time, so for some reason the SPI appears to not function as it should when changing from USB/debug to external power.

 

Has anyone run into this problem? I'm not sure what's different from running the codewarrior debug vs the microcontroller on external power. Any help in pinpointing the problem would be much appreciated.

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