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Friday, 16. May 2008
Flash Problems

I'm building a project using the AVR ATMega8 microcontroller. Once I got the thing wired up to where I could write firmware to it I found that it was always failing. I made a .hex file full of 0x10 values (256 bytes worth) and tried uploading that to the chip. The 0x20, 0x60, 0xa0, and 0xe0 lines were still blank (0xff). I guess the chip has some problems, so I rewrote my firmware to avoid the bad sections. I put the main routine at 0x30 and the sleep routine at 0x70. I found that the assembler uses word addresses, and that .org 0x70/2 is a valid address. I changed it to 0x38 just because the calculated address was weirding me out.

Then it also turns out I forgot to initialize the stack pointer (two bytes on Mega8 by the way). Got that fixed, adjusted the timing, and now it's working. Unfortunately I didn't select matching LEDs when I build the circuit board, so I think I'm going to start over with a new board, new LEDs and maybe even a fully functional Mega8 chip.

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5340 days of detection
mod: 12/3/08 5:42 AM

days of detection

... PMOG
... ideas
... brain hurts
... weblo

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Biography

Randall Bohn lives in Orem, Utah, USA. He works as a Software Quality Engineer. He is a big fan of the AVR line of microcontrollers. He has been in the computer industry since 1989. Randall is married and has three children.

rsbohn can be reached via gmail.com.


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