JTAGICE mkii, stk500 and debugWIRE

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I am unable to get my JTAGICE mkii to debug an ATTNY85 on my STK500.

I wrote a small testcase that blinks the LEDs. I connected the mkii to the SPROG1 ISP connection on the STK500. All appears to work fine. I can use the mkii to program the attiny85 with no problems. Once I have programmed the device, the LEDs blink as expected.

I then load the elf file into studio and attempt to debug. I get a window saying debugWIRE is disabled and then select the "enable debugWIRE with SPI" radio button. I then get a window saying to cycle power on the device to start debugWIRE mode.

After cycling power on the device, the LEDs no longer blink and I get an error message saying "failed to re-enter debugWIRE mode. Make sure reset line is clear."

The reste line is clear except... The manual says I need to connect the RST pin on PortE of the STK500 with PB3 to use ISP programming with the ATTINY13. I also found I needed to do this for programming with the mkii. I assume this adds no more then a few inches of trace and wire to the path. Should not be enough resistance to cause an issue for the debugWIRE should it?

Anyone else used debugWIRE and an mkii with an 8-pin device on an STK500? Any ideas where I am going wrong?

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Quote:
The reste line is clear except..
So you have removed the reset jumper on the STK500 I suppose.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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Yes,the reset jumper is removed.

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This AVRTV episode covers using DebugWire (Debugging with JTAGICEmkII):
http://www.avrtv.com/2008/09/25/...

AVRTV Debugging with JTAGICEmkII Ipod and Zune link:
http://www.avrtv.com/wp-content/...

AVRTV Debugging with JTAGICEmkII QuickTime H.264 link:
http://www.avrtv.com/wp-content/...

According to this you cannot ISP program an AVR while DebugWire is enabled and you must remove any pull ups, capacitors, etc. on the AVR reset line. If you also want to ISP the AVR, you may need to manually remove this connection while using DebugWire. Just follow the AVRStudio documentation for hooking up DebugWire to your AVR on the STK500 and then use it in DebugWire mode.