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ATmega128 ISP problems

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Advanced Member level 4
Feb 22, 2002
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atmega128 isp

I soldered two ATMega128 chips on development boards and one of the chips had no ISP communication at all. The other worked for some time and it also finnaly quited too.
I also saw that the fuses were programmed and i never did it .
Now i have no more ISP communication .I can't even read the chip's signature .The MISO line appears dead .. Does any one had problems like these? I suspect that the problems come from my programmer . Any suggestions about how to deal with these chips? .Or recomendations on how to avoid problems with the ISP interface.

mega128 isp


Are you having anything else connected on the ISP pins ?? , they are also used for uart.

The "Trick" Atmel uses if doing both serial and ISP , is to use a HC4053 , and let /Reset select the ISP.

ISP is for programming the Chip.

If you mean SPI ....
The M128 does not use MISO/MOSI for programming the chip , just for SPI comms.

This is Atmels ref design guidelines

And their EMC guide

Do a search for the schematic of the STK-501 (Atmels M128 Reference board)
Schematic might be here

Or maybe have a look here (a single sided hobbyist board)
**broken link removed**


4 Common mistakes on a new Mega128

1: Dont connect the PEN pin , (you should NOT connect it)

2: It ships from factory with the Mega103 compatibility fuse set
    So it's a Mega103 , until you clear that one.

3: It ships from factory with the default 1Mhz internal oscillator enabled 
    (Fuses again). When programming via ISP , be sure the ISP programmer   
    frequency is max 1/4 of clockspeed. 

4: MISO/MOSI isn't used for programming the chip


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