Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.arch.embedded > #31097

Re: Cortex-Mx MCUs with SWD access locked

From David Brown <david.brown@hesbynett.no>
Newsgroups comp.arch.embedded
Subject Re: Cortex-Mx MCUs with SWD access locked
Date 2022-06-24 14:15 +0200
Organization A noiseless patient Spider
Message-ID <t949sk$4jp$1@dont-email.me> (permalink)
References <t92mgi$d1l$1@dont-email.me> <t93vu7$ukp$1@dont-email.me>

Show all headers | View raw

On 24/06/2022 11:25, pozz wrote:
> Il 23/06/2022 23:38, pozz ha scritto:
>> Do you have some suggestions?
> 
> Today I found that SWDIO signal isn't able to swing normally between GND 
> and VDD on broken MCUs. I suspect something bad occurred inside the MCU, 
> but it's strange it happened on three different boards with three 
> different MCUs.
> 
> Could it be ESD?

I don't know these particular microcontrollers in detail, but there are 
two things that can cause problems with debugging that I can think of.

One is that you can often re-use the pin as a GPIO.  If your program 
re-uses the debug pins as GPIO, then maybe this is happening before the 
debugger can get access.  The debugger should be able to fix this if it 
has access to a hard reset pin, but some setups are missing that.

The other is that sometimes you can disable the debugger for security 
reasons.  I've done that by accident on a microcontroller (an AVR, IIRC).


Of course you could always have had damage from ground loops, spikes 
when plugging the debugger in and out (if power is on), short-circuits 
when trying to use an oscilloscope probe with clumsy fingers, etc.  If 
you have access to an X-Ray machine, you might be able to get some idea 
about what happened.

Back to comp.arch.embedded | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Cortex-Mx MCUs with SWD access locked pozz <pozzugno@gmail.com> - 2022-06-23 23:38 +0200
  Re: Cortex-Mx MCUs with SWD access locked pozz <pozzugno@gmail.com> - 2022-06-24 11:25 +0200
    Re: Cortex-Mx MCUs with SWD access locked dalai lamah <antonio12358@hotmail.com> - 2022-06-24 12:22 +0200
      Re: Cortex-Mx MCUs with SWD access locked pozz <pozzugno@gmail.com> - 2022-06-24 16:27 +0200
        Re: Cortex-Mx MCUs with SWD access locked dalai lamah <antonio12358@hotmail.com> - 2022-06-24 16:42 +0200
          Re: Cortex-Mx MCUs with SWD access locked pozz <pozzugno@gmail.com> - 2022-06-24 16:56 +0200
            Re: Cortex-Mx MCUs with SWD access locked dalai lamah <antonio12358@hotmail.com> - 2022-06-24 17:16 +0200
          Re: Cortex-Mx MCUs with SWD access locked David Brown <david.brown@hesbynett.no> - 2022-06-24 18:26 +0200
            Re: Cortex-Mx MCUs with SWD access locked Dimiter_Popoff <dp@tgi-sci.com> - 2022-06-24 20:00 +0300
            Re: Cortex-Mx MCUs with SWD access locked pozz <pozzugno@gmail.com> - 2022-06-27 08:54 +0200
              Re: Cortex-Mx MCUs with SWD access locked David Brown <david.brown@hesbynett.no> - 2022-06-27 09:23 +0200
    Re: Cortex-Mx MCUs with SWD access locked David Brown <david.brown@hesbynett.no> - 2022-06-24 14:15 +0200
      Re: Cortex-Mx MCUs with SWD access locked pozz <pozzugno@gmail.com> - 2022-06-24 16:25 +0200
        Re: Cortex-Mx MCUs with SWD access locked Stef <me@this.is.invalid> - 2022-06-24 20:29 +0200
          Re: Cortex-Mx MCUs with SWD access locked David Brown <david.brown@hesbynett.no> - 2022-06-24 20:34 +0200
            Re: Cortex-Mx MCUs with SWD access locked Stef <me@this.is.invalid> - 2022-06-24 22:12 +0200
              Re: Cortex-Mx MCUs with SWD access locked David Brown <david.brown@hesbynett.no> - 2022-06-25 10:19 +0200
          Re: Cortex-Mx MCUs with SWD access locked pozz <pozzugno@gmail.com> - 2022-06-27 09:06 +0200
            Re: Cortex-Mx MCUs with SWD access locked David Brown <david.brown@hesbynett.no> - 2022-06-27 09:25 +0200
        Re: Cortex-Mx MCUs with SWD access locked Reinhardt Behm <rbehm@hushmail.com> - 2022-06-26 14:25 +0000
          Re: Cortex-Mx MCUs with SWD access locked pozz <pozzugno@gmail.com> - 2022-06-27 10:07 +0200
            Re: Cortex-Mx MCUs with SWD access locked Reinhardt Behm <rbehm@hushmail.com> - 2022-06-27 15:11 +0000
              Re: Cortex-Mx MCUs with SWD access locked pozz <pozzugno@gmail.com> - 2022-06-27 23:50 +0200
                Re: Cortex-Mx MCUs with SWD access locked Stef <me@this.is.invalid> - 2022-06-28 11:23 +0200
                Re: Cortex-Mx MCUs with SWD access locked pozz <pozzugno@gmail.com> - 2022-06-28 12:42 +0200
                Re: Cortex-Mx MCUs with SWD access locked Stef <me@this.is.invalid> - 2022-06-28 17:06 +0200

csiph-web