Jtag read voltage out of range

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Can a moderator please move this to In System Debugging and Programmers? * Done. Ross.*
I was reading a similar topic in this sub-forum when I created this, and didn't think to change it, my bad.

I've just got some new boards in today, and wanted to try out JTAG instead of ISP.
Problem is, when I try to read the device signature I get an error saying my Read Voltage is outside the range.

Sometimes its 1.3v, and sometimes its 2v, but I've measured it with my multi-meter, and there is 5v on the JTAG port, so something weird is happening.

MCU is 32u4, and programmer is an ICE.

ISP works fine, I've flashed the 32u4, and its working as a USB device. Only thing not working is JTAG.

 

 

Exact error message is...

 

Read voltage 1.3v is outside selected device's operating range: 2.7v to 5.5v.
Do you want to continue?

I guess I should also mention the JTAG port on my board is a 2.54mm pitch connector, so I had to make a 2.54mm to 1mm adapter, there are no shorts, and each pin is connected correctly.

Anyone know what could be causing this, or what I could try to get it working?

 

 

Edit: I also forgot to mention, I've tried continuing, I just get another error, which is..

 

No JTAG devices detected. Debugger command Activate physical failed.

Unable to enter programming mode. Verify device selection, interface settings, target power, security bit, and connections to the target device.

Timestamp:	2019-07-15 21:41:03.295
Severity:		ERROR
ComponentId:	20100
StatusCode:	1
ModuleName:	TCF (TCF command: Device:startSession failed.)

No JTAG devices detected. Debugger command Activate physical failed.

 

Last Edited: Tue. Jul 16, 2019 - 05:46 AM
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well, it still seems like a wiring problem......

Have you connected the voltage to the right pin? I know on the ARM processors there are 2 voltage pins, connect the wrong one and you have the same problem.

 

Note that ISP and JTAG require different processor pins, so while ISP might be working as it is wired correctly JTAG might not.

 

Please post your schematic then we can see how things are connected...

 

another thing that popped to mind is that it might be that you have the connector mirrored.

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Silly question but you are powering the boards separately? You aren't relying on the JTAG interface to power it?

 

(reason being that Atmel ICE only sense the board voltage (to adjust their level converters), they don't supply power).

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Sorry I took so long to respond. Got caught up with work for a client.
 

meslomp, I am working with AVR, not ARM. But here is schematic.
Double checked my connector, doesn't have shorts, and VCC is showing 5v with both grounds.

Clawson, yes, the board is powered by USB.

 

 

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The JTAG connections seem right

 

what I miss though in your schematic, but might be present, is were AVCC connects to VCC. note that even though you might not use ADC you do need to connect AVCC to the VCC supply.....

 

have you not accidentally mirrored the connections?

Have you checked that pin 1 on hte board actually connects to pin1 of the flat cable?

 

I assume that will not be the problem, but have you disabled JTAG by changing fuses?

 

 

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AVCC connects to VCC with L2, top left of the MCU.

 

No they aren't mirrored, all pins are going to correct place.

 

And JTAG is enabled in fuses.

 

Man this is so weird, maybe I got some bunk MCU's.

 

 

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Have you managed to measure the voltages with a scope?

you do not seem to have any regulation between the USB supply connection and the actual CPU.

Also I see an awefull lot of capacitance on the bus. IIRC you are allowed to have a max of 5uF directly connected to the bus in order to reduce the inrush current and thus avoid the PC shutting down and then re powering the bus to check if there is a short on the bus.

I think best thing to do is now start to see what actually is happening on the supply with a scope. A voltmeter will not tell you exactly what is going on.

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No just the meter, I will try the scope and report back.

As for that capacitor, my initial design didn't even have a cap there, but then found something in the datasheet telling me to put a 10uf cap on it.

 

Found it.

Page 259 of the 16/32u4 complete datasheet, under 21.5 Design Guidelines, it says "A 10μF capacitor is highly recommended on VBUS line".

Anyways, I'll go check it with the scope.

Edit: There is 5 volt on the scope as well, nothing seems to be out of the ordinary. Although, there is 5v on all the Txx jtag pins (TCK, TDO, TDI, TMS), is it supposed to be like that?

 

Edit2: Ok I just measured again forgot to try with/without the ICE connected to JTAG. Without the ICE connected, all the Txx pins are 4.2v. When the ICE is connected, TDI is 0v, TDO is 3.7v, TMS is 2.1v, and TCK is 0v.

Last Edited: Sat. Aug 3, 2019 - 04:11 AM
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If you can try with another debugger and it all works you may have blown the input protection chip just behind the socket for the JTAG cable, it happened to me once.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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Ah, that would suck, especially because this is my only debugger, other than my MPLAB Snap for pic, which I also recently got.
This is literally the first board I've tried to use with JTAG, so chances are its not the issue, fingers crossed, but it does seem like something I would do at least once.

You did give me an idea though, I'm going to see if I get JTAG working on an Arduino Mega.

 

Edit: Ok same issue with the arduino, I'll try making another adapter, and if it still isn't working, I guess I'll either see if Atmel can fix/replace, or I could try replacing the input protection myself.
May I ask what you did with your device?

Edit2: Just comparing SPI and jtag, they use almost all the same pins (minus TMS/nTRST), so I don't think its fried.

Last Edited: Sun. Aug 4, 2019 - 05:58 AM
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I could try replacing the input protection myself.
May I ask what you did with your device?

That one laugh you can easily get the chip. As a last resort you can just de-solder the chip, if everything works then you know where the problem lies.

 

Just be very careful with the chip removed though, you don't want to cause more damage.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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Please do not go hacking pcbs yet.

 

What exactly do you own?   e.g. debuggers,  working boards.

 

If you have a SNAP and MPLABX 5.20 you can use it with Arduino MEGA2560 board.

Likewise,   ATMEL-ICE and AS7.0.

 

Take notes on paper as you take each step.   Number each step.

Then someone can walk you through each step.   And see where things go wrong.

 

It is always safer to start with a working board e.g. an Arduino Leonardo, Micro, MEGA2560, ...

 

Yes,  you can solder a TQFP onto a DIP adapter,  breadboard,  crystal, caps, ...

But there are too many things to get correct.

 

David.