STK500 ISP external device errors

[tronicgr]

Hi,

I made an PCB board that has an ATmega8535 on it for a motion simulator project. I also added ISP connector to be able to program it without need to remove it from its place.

The problem is that while the Atmega8535 is programmed without errors on my STK500 development board, using a cable to interconnect the ISP connector from STK500 to my PCB give me errors and can't program the ATmega8535.

I have placed a indication led to watch the reset line and seen that the STK500 is barely able to pull low the line, while a cheap serial programming circuit I used with ponyprog works fine on the same ISP connector.

Just some info: The PCB has its own power supply, and the Atmega8535 is running with a 16Mhz crystal. No other components are connected to the Mosi, Miso, CKL lines to interfere with them...


Any ideas why this is happening?

Regards, Thanos
Greece, Athens

[th_sak]

You have to remove some jumpers from STK500. Remove VTARGET and XTAL1 jumpers. You must also supply the onboard voltage of your circuit to STK500 +5V pin of the ISP connector.