J-Link Reset issues

kas219 · Jan 4th 2011, 7:25pm

I am using the J-Link EDU unit with IAR 6.1 to develop code for an At91SAM7 microcontroller and I have some questions regarding hardware resets. My understanding of the J-Link is that RESET pin (pin 15) of the JTAG can be used to force a reset of the processor by being pulled low. I have a logic analyzer set up to monitor the reset line but I have not been able to find a way using the IAR embedded workbench reset command to toggle the line. I have tried several of the reset strategies provided in the setup options but have not found a way to make it work. So my questions are:

1. Is what I am trying to do possible?
2. If it is, does anyone have any things to try
3. Is there a recommended macro file to use with IAR and the J-Link

Thank you for your help.
Keith

SEGGER - Alex · Jan 7th 2011, 9:13am

Hello Keith,

>>but I have not been able to find a way using the IAR embedded workbench
>>reset command to toggle the line.

What exactly do you mean here.
Are you talking about the time when the debug session is started?
At this time, a toggle of the reset line should be possible when selecting the reset strategy "halt using breakpoint" or "halt at 0"

To get the reset button in IAR EWARM performing a toggle of the reset line, the following lines should be added to the macro file:
execUserReset() {
__message "execUserReset()";
__hwResetWithStrategy(0, 1);
}

Please note that the recommended reset strategy for Atmel SAM7 is reset strategy 0,
since then J-Link auto-detects what is the best for the device and on the Atmel SAM7
this is a reset of the peripherals by writing the RSTC_CR register.
On the Atmel SAM7S by default the reset pin does not have any effect. It has to be enabled via software first.

Best regards
Alex

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