Connection question; JTAG

Development Boards MicroMod
1

Hi! Just a quick question about pin configurations and JTAG.

I wish to buy the AVR JTAG from Olimex and connect onto my mega16 on my own designed PCB, for field update and debugging. I see from Olimex homepage how TCK,TDO,TMS,TDI, VCC and GND should connect. But what about the NSRST and NTRST pins…how do I connect these one´s to my mega16? Is that for the RESET* signal of the mega16 to be pulled low during the programming?

Also, is there any special considerations to look at if I use my mega16´s SPI interface and UART interface for external communication? I mean when using JTAG? Reason I ask is that i have to make my design of the PCB before I have a chance to try out the JTAG interface. This means that the mega16 will be totally unused before soldered to the PCB (risky I know) and have to be programmed and set when soldered.

Thanks for a good forum

Yours Very Sincerly

/ Peter

2

check our avr-M16 schematic it’s posted on our web

Tsvetan

3

Thank you very much for that! Helped a great deal!

Yet I wonder, lines are drawn from the reset and aref part of the connector on that schematic…but is there a reason for those beeing left open? something that should connect to these?

Another question arose…when using JTAG programming, should the design be made so that all pheriperals are turned of? Can they affect the reprogramming, or first time programming? Or even fuses?

What I am after is if I should have any swithces for turning of and on power to perhiperals (or so)? Apparantly this is not the case when using the debug interface :slight_smile: as everything has to be up and running!

Thank you very much for your last reply!

Kind regards/

Peter

4

:oops: sorry for bothering again…

After I looked a bit closer to the schematics of the avr-m16 board you kindly posted, there came up a few new questions (except for the ones above)

  1. PBO (T0) of the AVR mega16 is connected to the NTRST pin of the JTAG connector. What is the reason for this? I just got a bit confused…

  2. I wrote in my last post that the reset (pin 6 of the JTAG connector, NSRST) was left open. I saw that this one was connected to the RESET* of the avr (as a global port in the schematics). Could this be confirmed?

  3. AREF of the JTAG connector was connected to AREF of the mega16…can this be confirmed? Does it need to do this?

Thank you for your patience and help!

/Peter