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jtag on 32u4 3v
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jtag on 32u4 3v

by d3xt3r01 on Wed Mar 17, 2021 6:23 am

Hi,

I'm trying to debug an issue with my code using an atatmel-ice using microchip studio. The ISP connection doesn't support debugging.
What would be the pinout for jtag ?

Thanks.

d3xt3r01
 
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Joined: Wed Mar 17, 2021 6:21 am

Re: jtag on 32u4 3v

by d3xt3r01 on Wed Mar 17, 2021 8:27 am

Found A0-A3 pins connected to the following on the atatmel-ice 10 pin minisquid
A0 : TDI - pin9
A1 : TDO - pin3
A2 : TMS - pin5
A3 : TCK - pin1

pin2 and pin10 GND
pin4 connected to the voltage reference ( powering the itsy from 2x1.5V batteries for example )

I think I got them right, now to burn the jtagen fuse !

d3xt3r01
 
Posts: 3
Joined: Wed Mar 17, 2021 6:21 am

Re: jtag on 32u4 3v

by d3xt3r01 on Wed Mar 17, 2021 9:18 am

More tinkering got me to this:

The defaults:
avrdude: safemode: Fuses OK (E:CB, H:D0, L:FF)

Updated using avrdude ... -U hfuse:w:0x10:m
avrdude: safemode: Fuses OK (E:CB, H:10, L:FF)

And I'm off to the races with jtag, all seems to work ok so far !

d3xt3r01
 
Posts: 3
Joined: Wed Mar 17, 2021 6:21 am

Re: jtag on 32u4 3v

by adafruit_support_mike on Thu Mar 18, 2021 11:23 pm

Yep.. I'd forgotten that the ATmega32u4 has a JTAG interface, but it is listed in table 10-13 under section 10.3.6 of the datasheet: Alternative Functions of Port F

Glad to hear you got it working!

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Please be positive and constructive with your questions and comments.