RSTPINCFG (enable RESET functionality) on ATmega4809 can interfere with UPDI?

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westfw
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Posted by westfw: Mon. Nov 26, 2018 - 04:04 AM
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So I wanted to make the RESET button on my ATmega4809 Xplained Pro actually reset the CPU (not the default, apparently), and went into the Device Programming Panel of AS7, to set the appropriate fuse bit (RSTPINCFG)

 

It's giving me a warning:

 

Changing the RSTPINCFG can disable the UPDI pin.  Only debuggers with 12V activation functionality can restore UPDI functionality if UPDI is disabled.

 

So: I can't find anything in the datasheet about RSTPINCFG having any effect on the UPDI pin, or about UPDI ever getting disabled on a permanent basis (the pin is described as "dedicated"), or about anything 12V-ish ever being involved with UPDI.  WTF?

 

I would rather not brick my board...   Is it safe to enable external RESET functionality?

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AVR Microcontrollers, megaAVR and tinyAVR
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Bronze Markjs
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Posted by js: Mon. Nov 26, 2018 - 05:15 AM
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I think I questioned that thing before and it seems to be just a Studio "feature" however if you brick your board don't blame me. cheeky

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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kabasan
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Posted by kabasan: Mon. Nov 26, 2018 - 06:13 AM
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It seems that the device definition on AS 7 side is still insufficient.
Selection of RSTPINCFG in ATmega 4809 is RESET or GPIO and does not affect UPDI.
Actually I can continue debugging while enabling RESET in ATmega 4808.

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westfw
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Posted by westfw: Mon. Nov 26, 2018 - 06:14 AM
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Old thread: https://www.avrfreaks.net/forum/atmega4809-reset-pin-fuse-bug?skey=RSTPINCFG

 

(Thanks!)

 

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