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RP2040 FEATHER - SWD pads....
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RP2040 FEATHER - SWD pads....

by coax006 on Wed Apr 07, 2021 1:58 pm

Greetings RP2040 Adafruit fans...

When looking at the Adafruit RP2040 feather pcb, I can't help but notice the TEN surface mount pads for a SWD header (0.050 inch pitch)......

Can someone recommend a specific header to solder there? ... What debugger to use? ... Has someone added a part and used this debug port?
ALSO, could someone use another PICO or FEATHER for debug, as in the "PICO getting started" document?

( FYI: I am happy to get a Rasp Pi 4 to SWD connect to a PICO, and actually DEBUG on the Rasp Pi 4 per the "getting started" doc ... )

Thank you in advance!

coax006
 
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Re: RP2040 FEATHER - SWD pads....

by mikeysklar on Thu Apr 08, 2021 5:40 pm

@coax006,

This is the 0.05" SWD connector.

https://www.adafruit.com/product/752

It is mentioned on the Adafruit Feather RP2040 product page:

Optional SWD debug port can be soldered in for debug access


We have a llttle bit more about using the SWD pins on our pinout page in the product guide:

https://learn.adafruit.com/adafruit-fea ... 3084856-26

For advanced debugging or to reprogram your Feather RP2040, there is a footprint to solder a 2*5 pin 0.05" standard SWD header on the board. The image above shows the "pin 1" location by marking it with a triangle. This orientation places the connector key facing towards the end of the board where the USB connector is. This allows you to use something like a Segger J-Link and a 1.27mm SWD cable to connect from your PC to the Feather.

mikeysklar
 
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Re: RP2040 FEATHER - SWD pads....

by coax006 on Mon Apr 12, 2021 7:58 am

Thank you for the reply with links...

ALSO, perhaps "Feather" should be two different Forum topics, one separate one for RP2040?

coax006
 
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Re: RP2040 FEATHER - SWD pads....

by mikeysklar on Mon Apr 12, 2021 6:43 pm

Our Feather boards include many processor variants 32u4, M0/M4, RP2040, ESP32 and nRF52 to name just a few. It is a generic term for a small form factor with maximum pin exposure not tied to a specific architecture.

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Re: RP2040 FEATHER - SWD pads....

by mookiedog on Tue Sep 28, 2021 7:54 pm

I just went to the trouble of soldering the header to my Feather RP2040. It was not the easiest job. I cleaned off the pads with solder wick, then applied solder paste from a syringe and used a really fine tip soldering iron. Call me lazy, but I wish that it was an option to get it soldered from the factory.

But that's not why I am here. After getting it soldered, I fired up the blinky example on Segger Embedded Studio and hit F5 like normal to flash code and run the debugger. I got the following error:

The connected J-Link does not support SWD multi-drop. Debugging an SWD multi-drop system is not possible.


Googling that error indicates that there are two issues. Number one is that an RP2040 has two cores, each with its own debug unit. The debug units share the single set of SWD pins. That's what multi-drop means. The bigger issue for a lot of us out there is that according to Segger, you need a J-Link based on internal hardware that is at least revision 10. Mine is rev 8 (probably like most people in the world) which has been around forever. It is surprisingly difficult to find out what version of hardware is inside a Jlink that you find for sale on the web. Anyway, no debugging for me today.

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Please be positive and constructive with your questions and comments.