Raspberry Pi Foundation launches $12 USB Debug Probe The Raspberry Pi Foundation has a new gadget: a cheap, easy USB probe for debugging bare-metal code on a Pi Pico… but it should work with several other devices too. The Debug Probe is a device to help debug bare-metal software on the Raspberry Pi Pico. The Pico is the Foundation's $4 single-board computer for microcontroller …
In this context, OCD stands for On-Chip Debugger.
Are you sure? The (human) debugger must surely have some obsessive compulsive disorderly behaviour to cope with computers in general. And the little computer in need of the SWD interfaced session(s) is certainly behaving obsessively compulsive of the wrong type. Otherwise you wouldn't need the SWD interface, you know.
I'd say one OCD is accompanied by the other OCD to get things fixed.
[Author here]
> I paid something to the tune of €25 (incl. 25% VAT) for mine a few years ago.
Yes, I must confess, when looking at the pricing, I didn't notice that the price on the educational device was for a 12-pack of them. My mistake, and we've amended the article. My thanks to Segger for pointing out this error to me.
Maybe try solving your supply chain issues first
It's Pico based. There's been no supply chain issues for that chip.
By definition a supply chain issue isn't the fault of the entity on the end of the chain. What do you expect the Raspberry Pi Foundation to do, set up a fab of their own?
Important stuff?
The Pico has been far more interesting to me over the last year or so than boring old fashioned R'Pis![1] Let's be honest here, with the R'Pi 4 everyone is talking about how good it is at doing "all the stuff a normal desktop can do" so just make do with a cheap (old) desktop in the meantime.[2]
Anyway, you want them to stop designing and selling stuff that *can* be produced in the current supply climate? Let everyone else in the organisation twiddle their thumbs because the supply managers can't get hold of parts?
[1] admission: yes, I do have a few R'Pis in use, PiHole, a couple of Augmented Marty robots and the like, but mark 2s are doing the job.
[2] yes, there are lots of uses, including industrial; just getting snarky at the idea of someone bitching that just 'cos what *they* need isn't available, especially for reasons beyond R'Pi's control, everyone else must also suffer.
The article is unclear what advantage this has over using a pico as a probe. Yes, it does require some setting up - soldering four pins onto it to attach jumpers, and flashing the debug firmware from a PC (or a full-fat Pi) via a USB cable, but it's not exactly rocket science. I have one sat next to me (covered in a layer of dust, to be fair), and even with my meagre soldering skills, it didn't take much effort to set it up.
So, does this come with some advantage over the Pico + five minutes with a soldering iron, or is it pure convenience?
Pure convenience, ready made cables and a nice package with the case. Plus you don't risk staring at your Pico with the probe s/w loaded and be tempted to unhook it and plug it into a new project - which then needs to be debugged...
To be honest, I wish I'd known this was on its way - and when it would be available - as I only soldered a Pico onto a convenience "probe PCB" (which brings out the connections nicely arranged) in January and that, without any case, came to more to 12 quid in total. Sigh. Never buy tech - it will be cheaper tomorrow.
A) it will empty your wallet some more . .
B) it will distract you from complaining you can't buy a pi . .
secret bonus answer for the tin foil brigade . .
C) because some corporate clown has a new 'Ebon' suit, and is craving sugar water . .
Yes, I went and had a look at the actual product link as well. They seem to admit, without actually admitting it, that this is essentially just a pico with a different shaped carrier board, connectors pre-soldered, and debugger firmware pre-flashed.
It's great that the RP2040 is such a versatile chip that this sort of thing is easy to make with it, but to me, it seems like one of its big selling points is its versatility, and that versatility is better exposed on a Pico, with all the pin-outs. For someone who is looking to use one of these as a debug probe, I'd also expect them to be working away with a soldering iron coming up with all sorts of uses for the thing they are debugging with it, so it's a bit of a no-brainer to also be able to turn a pico into a debugger easily, given that it's really part of the same skill-set. And it is literally very simple to do, five minutes of soldering (adding four headers which are all next to each other) and flashing from a PC via USB.
I suppose for someone who is trying to hack a pico to work with specific hardware, being able to attach a ready-made debugger to that to dig into what exactly it is doing would be handy, but I'd also be surprised that there is a massive market for this group that doesn't overlap significantly with the former group, because as far as I can see, this is just a pico on a different shaped carrier board.
I'm sure there is something I am missing here. I'm not a massive embedded electronics kind of guy, and only really play with the couple of Picos I have, so really I'm just hoping someone can enlighten me.
True enough, but:
Getting a V3 *not* in the US always seems to be way more than $11 whenever I look, especially without a company account - although there are loads of (what clam to be) V2 clones for $11. If one is feeling trusting.
This also has the advantage of being a ready-to-go, guaranteed to plug into a Pico without having to figure out if the wiring is correct, device. That is probably going to be a big advantage when introducing OCD to beginners, which is still a big chunk of the the target market: expect plenty of step-by-step articles with pictures very soon.
Heck, it is tempting to get one of these just for that reassurance, instead of worrying about whether the jumper leads have been nudged again, are they in the right order, did I really remember to flash the probe s/w, then why isn't it making any connection *this* time, mutter, mutter (sometimes debugging can send one a bit doolally).
More than a little unclear!
Safest to read every mention of "Pi" as meaning "Pico", it all makes sense that way.
As to to your actual question, there are a few articles on the web that discuss using a normal Pico as a JTAG debugger - can not vouch for it as haven't tried - for example
https://projects-raspberry.com/need-a-jtag-adapter-use-your-pico/
Though haven't yet spotted anyone saying they used one to debug a Raspberry Pi (the only article I know of that does anything with JTAG into a R'Pi is
https://sysprogs.com/VisualKernel/tutorials/raspberry/jtagsetup/
and, again, just read it for curiosity, can not vouch for it).
So it sounds like it ought to be possible. Would be nice to see the two used together, Pico into Pi.
[Author here]
> Safest to read every mention of "Pi" as meaning "Pico", it all makes sense that way.
No, it's not safest. That is not what I wrote or what I meant. I am sorry for being unclear and I am adding a bit of explanation right now.
The Pico is an embedded device. It does not normally run an OS. So, it makes sense to debug a Pico using SWD and a debug probe.
But the bigger Pis _do_ run an OS and you can run an OCD tool directly on a Pi Zero, 3 or 4, and use some pins of the GPIO to talk SWD to the embedded device you wish to debug -- without needing or using a debug probe.
No, you can't use a bigger Pi as a debug probe, but you don't need one: the GPIO bus talks SWD directly without the need for a probe.
This is _not_ all about Picos and no you don't need a PicoProbe if you run the OCD on the Pi itself.
I hope that is clearer. It's what I tried to say, but it seems I was too brief and that caused confusion.
[Author here]
> As far as I can ascertain, Raspberry Pis don’t have an SWD
Yes, they do: you can use a few pins of the GPIO interface to talk SWD to another device, so if you run OCD software on a Pi Zero/3/4 you can debug another embedded type device directly, a Pico or Teensy or Arduino or whatever, without using a separate debug probe.
In other words, the functionality of acting as a debug probe is built into the RasPi.
No, you can't probe a big Pi, because it's not an embedded device: all the bigger Pis run a dedicated real-time operating system (RTOS) called ThreadX on the VideoCore GPU, and that OS is what's in control of the computer. The GPU boots first, then it loads a kernel into the Arm core(s) and starts the Arm running.
Since the Pi was launched, Microsoft acquired the company that wrote ThreadX and has rebranded it as Microsoft Azure RTOS or something.
Citation: https://en.wikipedia.org/wiki/ThreadX
I'm glad that you are looking to clear up anything confusing in the article, but you could still do better than to misrepresent what was said in these comments in order to make your point:
>> As far as I can ascertain, Raspberry Pis don’t have an SWD
> Yes, they do: you can use a few pins of the GPIO interface to talk SWD to another device
Hmm, sorry, but I think it was quite clear that was only asking about using SWD *INTO* the R'Pi, as he wrote (past the bit you quoted)
>> Raspberry Pis don’t have an SWD, while Raspberry Picos do. So you can’t use a Pico to debug a Pi
> if you run OCD software on a Pi Zero/3/4 you can debug another embedded type device directly, a Pico or Teensy or Arduino or whatever, without using a separate debug probe.
Yup, no-one disputes that.
> No, you can't probe a big Pi, because it's not an embedded device
Doesn't need to be embedded to be probable! Probing it will probably make a right mess of the OS timing, so you don't want to use a probe normally - unless you are trying to get into the Linux kernel and related bits (kernel modules). Which is what the other article I linked to is all about:
https://sysprogs.com/VisualKernel/tutorials/raspberry/jtagsetup/
@Liam thanks for the extra info!
Yes, I should have been clearer in my comment. I was asking if it's possible to debug a Raspberry Pi (Zero/3/4) using SWD. I have seen the same tutorials for using JTAG, but I hadn't seen any for using SWD, so I assumed it wasn't applicable for non-Pico Pis.
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