JTAGICE mkII doubts

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Hi !

During programming with JTAGICE mkII I measure 3.0-3.15 V on pin 6.

Shouldn't be this pin 6 tied to GND during programming?

I suppose that JTACICE mkII also has some internal pull-up. I added external pull-up 100k resistor in current PCB and on previous PCB 4k7 in parallel with 100k, so that's less than 4k7.

From forum:

Quote:
you shouldn't have a powerful pull-up resistor or any capacitive load.

Consider the reset line a high-speed digital signal, and not the normal static reset connection you would. I've never had a problem with the MKII, but have always had nothing on the reset line. I added a jumper to seperate the AVR's reset line from the rest of the board when using the MKII.


So what is recommended resistor value on RESET line?

From time to time JTAGICE doesn't recognize chip, then I power off/on it and board and it's fine then.

I've never had any problems with programming, AVRStudio didn't report any software problems during programming any verifying.

From user guide:

Quote:

Always switch off the target application power before switching off the JTAGICE mkII. Never leave a powered-down JTAGICE mkII connected to a powered application - current may leak from the application and result in damage to the emulator.

I don't stick to that. And you?

Does it matter what do you power on/off first?

Thanks guys !

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Quote:
Shouldn't be this pin 6 tied to GND during programming?
No, it only gets pulsed briefly on entering programming mode.
Quote:
So what is recommended resistor value on RESET line?
I have always used 4K7 with 100nF cap to ground.
Quote:
I don't stick to that. And you?
Always do stick to that, at times I mess up though and I get the shivers thinking the JTAG is gone. Once it did die but manged to repair it.

edit actually I was thinking about ISP programming, the reset pin may not be used at all in JTAG programming. It it used if JTAG is disabled in software to regain control of the chip.

John Samperi

Ampertronics Pty. Ltd.

https://www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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Thanks, JS !

js wrote:
Always do stick to that, at times I mess up though and I get the shivers thinking the JTAG is gone. Once it did die but manged to repair it.

How do you connect JTAGICE to board? I mean what do you do first?

Connect JTAGICE to board, power it ON and then power ON board?
Or some other way?

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Quote:
Connect JTAGICE to board, power it ON and then power ON board?
Or some other way?

That's how I try to do it all the time. I sometimes forget, but my JTAGICEmkII hasn't died yet.

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Thanks guys so far!

xtal_88 wrote:

During programming with JTAGICE mkII I measure 3.0-3.15 V on pin 6.

Shouldn't be this pin 6 tied to GND during programming?


js wrote:
Quote:
Shouldn't be this pin 6 tied to GND during programming?
No, it only gets pulsed briefly on entering programming mode.

My board works on 3.3V, so VDD is 3.3V
When I start programming it drops for about 0.2-0.3 V.
So if RESET pin drops for this 0.2-0.3 V , why doesn't it drop to 0 V.
This 0.2-0.3 V doesn't make any sense to me, I don't know.

JS and jayjay1974, waht do you measure on your JTAGICE pin 6 or RESET pin during programming?

js wrote:
I have always used 4K7 with 100nF cap to ground.

I found in datasheet, AVRStudio help:
Quote:
2. Remove all capacitance or drivers on the RESET-line. Make sure that a any pull-up resistor is larger than 10kOhm

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It is only debugWIRE that is fussy about capacitance on the RESET line.

ISP brings RESET low at the start of programming and releases afterwards. You can probably get away with about 20ms risetime. 10k * 100nF = 1ms so I guess that anything less than 2uF would be within 20ms. And it is the fall-time you need for an AVR. So that 10k is nearer 100R (or less).

JTAG does not even use RESET. Only if a JTAG software reset fails does it prompt you. And then you will have a similar situation to ISP. Except that JTAG might even drive RESET in push-pull. So both rise and fall time will be with a low o/p resistance.

So the simple answer is: use a 10k pull-up on /RESET line.
If it is a debugWire chip, use no capacitor when debugging.
Any other chip can use anything from 0nF to 1uF.

I have never measured the voltage on /RESET pin.
I guess that it will be 0.1V during ISP.
It will be 3.3V during JTAG debug or programming.
It will be 1.7V during busy debugWire.

David.

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Thanks David !

Now I can program with JTAGICE, but it won't start debugging.

AVRStudio :

Quote:
Platform has been disconnected, leaving debug mode.

JTAGICE mkII: Timed out while waiting for response from the emulator. Please check cables and emulator power.

Is it dead?

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If you can program with it it is 99% alive I'd say.

Imagecraft compiler user

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Quite honestly, if you can program the AVR by JTAG, then you can debug via JTAG too.

You probably had to upgrade / downgrade with Studio6 / Studio4.

With AS6 you probably need to specify JTAG for debugging when you first start. If ISP is selected, you just get programming and no debugging. However the ISP won't work if you are connected via JTAG.

I note that you have never said which AVR you are using. Some Xmegas are PDI or JTAG. Some Megas are JTAG or debugWIRE.

David.