In-depth: Raspberry Pi Pico's PIO - programmable I/O! 

Not sure where that leaves the rest of us Luke. 🤦

Once you get the hang of it :-D let us know ... we will bug you for a step by step tutorial that takes us from the pio blink example to writing our own pio stuff. I'm still really puzzled on the raw C helper function % c-sdk

Pilot Induced Oscillation is a pretty scary thing to get into. :)

You know that you are comparing Apples and Ataris, don't you? In addition, it won't do any harm if Arduino burns down. That was a joke, of course. Frameworks burn badly, or not at all, when they are mental constructs;) Don't forget: use the right tool for the right job. In some of the comments here you can clearly see how strange a high-speed logic with discrete building blocks is to people. To know about that too can sometimes be an advantage. Or simply have knowledge besides the Arduino, ESP or Raspberry filter-bubble. www.digikey.com/en/products/filter/embedded-microcontrollers/685 ... Fucking 89483 results!

@@dieSpinnt The AVR market is not going to change, I am just fearful of Arduino's position here. You could get a bare bones AVR chip for a comparable price to the pico even after the demise of Arduino no problem. It would only really show how expensive their stuff are and pressure them to act. Whatever happens, knowledge is knowledge.

@@martandrmc Hmmmm, I can't see us both discussing the (insert MCU here) Market. Who buys, calls! In retrospect, my thoughts on your Arduino worries to calm you down: If you have to do something quickly, use a BAD editor (I just don't understand why people pick it up. It's a free decision to use a text editor and not code-completion mumbo jumbo or the other way arround) ... in other words: one that works (!) and you want to try something quickly (with thousands of others strengthening your back with their experience through libraries or support), again: something that works ... proven There is always a niche for this type of hobby or craft work. This niche can be really big, so big that even professionals can use it to quickly try out an idea. I think you shouldn't worry. Especially not because of diversity :)

May I show you something other besides my inabilities of soldering TQFP packages? www.st.com/en/microcontrollers-microprocessors/stm32h747-757.html#overview A powerhouse with camera interface, GPU acceleration and a pin header count that doesn't bring us both to a laughter as the pico. The same free tools and support from an industry leader (let us make jokes, later:)). Raspberry Pi Pico ? I don't see this as god's chip. Don't let you fool from the hype. There are Ten of Thousands out there, if not more ... to choose from. Edit: I cheated a little: for the price of the Pico, you have to give up graphics acceleration but you have up to 160 flexible IO lines .... You can then connect externally via the memory interface, as well as operate quad SPI memory and what works as a PIO there does a DMA controller for normal people. The one described has 4.

@@dieSpinnt In retrospect, comparing the 2 prices is not by any means the full story. There are devboards out there with an STM32 at around the same price as the pico that have better performance than an Uno but still have not gotten to be main-stream yet. Arduino has alot of software behind it that could also work with a Mega if performance is needed. In conclusion i dont think that Arduino is in as much danger as i have thought, but still the pico is backed by a similarly well-known company. It would not be equivalent to compare STMicro the same way. (Also sorry for not checking for a week)

Me too. I spent five solid years working with 6809,8085,Z80,68K and this video has left my mind reeling with questions like "Yes, but what can/can't you do with it?" I've seen one video of a guy who has recreated the original Transputer boards. I learned Occam for a bit on one of those.

Exactly. It's quite complicated if one is new to assembler. .wrap_target at video start :)

Thank you, that's great to hear! :)

Assembly language is delicious!

If you want a good challenge, try implementing string.h

Coming from Amiga programming background I always find myself reinventing the wheel... :) Love the low level stuff! I haven't watched the whole video yet, but somehow I think that the Amiga co-processor (Copper) has been made to do I/O

For sure quite a dry topic, tried my best to create it as a 'reference' :) Next one will have some practical examples, that should help!

Ok cool, cant wait for the next video

Agreed. as stack says, needs to be a reference first...but would be nice to show a very brief example of an instruction executing (like how the effect on square wave is demonstrated).

It would also help if he slowed down a bit. It's difficult to absorb information when it's blasted at you.

@@stacksmashing Maybe videos are not the best medium for a reference, surprising as that may be in the YT age.

You know it's the creme de la creme when you go 0.75 speed :)

Meanwhile, I'm watching at 1.5 and not fully processing everything. Oh well, I'm just trying to get the gist of it and I'll look at documentation when I'm actually working with it.

​@@chinoto1 Lel, I had to jump down to 1.5 from 3.5; video speed controller is my best plugin.

I’m actually working on clustering a bunch of picos to rebuild Ben Eater’s 8 bit computer (but planning on using 16 bit addresses instead of 4 bit addresses for memory; 65536 bytes instead of only 16 bytes). It kind of silly to build a (slow) cup out of a bunch of processes but some good things are: lots of lights, ability to experiment with cpu architectures quickly (easier than wiring lots of 7400 series chips), and it’s fun and I just want to haha. Python is good enough but I want to using PIO if possible.

Not sure where you're getting that definition. If it's from UML, then they've redefined the term. A state machine doesn't need an exit point. And it certainly doesn't need transitions defined between every state (if that's what you meant there). I've built many no-exit state machines, and almost none with all possible transitions allowed.

@@peter9477 de.m.wikipedia.org/wiki/Zustandsdiagramm_(UML) im Vergleich dazu der de.m.wikipedia.org/wiki/Endlicher_Automat

@@mr.unbekannt2163 I'm not sure what you're expecting me to get from that page. Are you claiming something in it contradicts me? Or are you claiming that the UML definition does require all possible transitions to be allowed? (In which case as I said they have redefined the term, and inappropriately, I might add.)

Someone did! www.reddit.com/r/raspberry_pi/comments/lhym1v/gameboypico_update_we_have_a_working_game_but/

Datasheets I presume

datasheets.raspberrypi.com/pico/pico-datasheet.pdf

Cypress' PSOC series have fpga like programmable hardware blocks builtin.

It's like a more accessible version of the Parallax Propeller.

You are absolutely correct, great catch! It's off for 1 cycle and on for 2 cycles. Added it to the errata. Glad you liked it!

He links to examples in the description

@@trhosking my bad. Thanks

So had the Z80: 'djnz address', which stands for Decrement and Jump if Not Zero, where register b (8 bit) was the one being decremented. But these very rare and useful instructions (for creating loops) have not much to do with this discussion about PIO, which are far more complex and programmable!

Oh, my first Super! Thanks a lot! :)

You are correct, but your timecode is wrong ;)

More like 8:55 but yeah.

(at time 2:59)

IGNORE my IGNORANCE... all relative to GPIOs. So input from GPIO's to FIFO buffers, to CPU(?).

Search for "Signal/Noise Ratio". One Wire ... ROTFL From Wikipedia: "1-Wire is a device communications bus system designed by Dallas Semiconductor Corp. that provides low-speed (16.3 kbit/s[1]) data, signaling, and power over a single conductor." There is a reason why this is low speed. By specification you don't need high-speed shenanigans like shown in the video and simply by the physics. It is impossible to get a good signal integrity via this bus-implementation at high frequencies. If you are flying up to the 100MHz+ range, nobody can deny technologies like LVDS and the study of high frequency behavior of electronics and the corresponding physics. Also, that the pico can theoretically generate these signals must not mean that he can also DRIVE the signals necessary. Don't get me wrong, please try your (by my understanding) worthless experiments. Maybe with a better bus? At least two wires? Well wired for high frequencies with buffers? The simulator: RTFM, I mean the data-sheet (Reference and Programming) and really ... you need a simulator for a $5 device you can debug and watch at the oscilloscope? Please stop joking ... no, have fun!:)

@@dieSpinnt If you want me to get a DSO by all means send me the money.

@@gudenau Nope. I am not forcing you into something. You can live without one, but then ... you simply can't do what you are trying to do. Just that:)

Jedzia you should really overthink your attitude, you are not contributing positively.

@@stacksmashing Take for example the very good qemu-arm emulator. It is impossible to translate timings to a real chip. High speed one-wire protocol ... I overthought it: He will try it with or without me. DSO: There are $29 STM32F103 based ones out there which would be fine for 16kbit/s. I don't gave that advice from thin air. To prevent tears and frustration! Low speed applications, but not for 200MHz SPI or something in that region .... which always works and you can as a bonus ... rely on! Skepticism is always not seen as positivity. But thanks that you RTFM and present that here with your videos. Can't wait for a real world app of PIO.

At 1:55 you can see DMA listed on the left side :)

Yes, PIO runs with system clock (so 250MHz overclocked) or you can set it to custom, lower frequency via a divider.

I have seen reports of the RP2040 being overclocked to 270MHz, but the Pico Dev Board UNDERclocks the CPU to 125MHz ...so remember to calculate your divider based on the clock speed returned by `clock_get_hz(clk_sys)`

pio is a programable co-processor of the RP2040 micro processor made by Raspberry Pi. STM32 is a family of microprocessors (I think the company name is ST Microelectronics) - there are probably more than a hundred different versions of STM32 microprocessors depending on what capability you need. Here is a video comparing the black pill with an STM32f411ceu6 with a Pico - ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-I2VcIKlL-9w.html

It is totally different from your RAM chip:) I think you meant a micro-controller with a 80ties series core(?). Totally different architectures (ARM)from a totally different time-period. Yes, such high-frequency functionality can be implemented with standard gate logic, FPGA or something similar. At all, first you have a problem and then you solve it ... not the other way around. Lets wait for some hobbyist talking about their +200MHz SPI and then have a good laugh.

​@@dieSpinnt I guess, I should rephrase. I am interested if there exist a readily available IC that could bring PIO functionality to other MCUs. I just recall this RAM chip used in some similar way in a schematic of some production device. That's why I saved it, but I am still lucking embedded designing/programming skills to read datasheets fluently to fully understand chips capabilities. I get that Picos PIO is built internally with the same logic that you could design externally with discrete parts, but that is like reinventing the wheel and a whole lot of work on a completely different level of EE, and there are problems like shared memory, that are probably not that trivial to solve, etc.. FPGAs are simply in a order of magnitude different price category, and the thing with reinventing the wheel still stands if there exist integrated solution.

@@Mr.Leeroy Simple experimenting boards for FPGAs are under $20. Chips, PLDs are a fraction of it. I think, this PIO is a nice gimmick and other MCUs handle problems given just equally good with other technologies like IRQ, normal buffers/plain old shift register, dedicated counters and DMA. ..... The problem comes first, then the solution:) So that PIO first has to show its superiority in a real world use case. An example of my skepticism: A traffic light control could be implemented very elegantly with this PIO facility. But that is far from being a high-speed application. In addition, this can be programmed exactly in the traditional way. Without any addition that might be extremely difficult to debug. The instruction memory is much too small and even more difficult to understand for fast applications. It's just old wine in new bottles. The timing has to be right, with or without a PIO. PIO is not cut off from the rest of the application ... And if it is (like a gimmick) it means that the rest of the processor is bored and I would not have needed PIO in the first place. Have you seen Schmitt-Trigger inputs as such for high-speed I/O? Not me:) And I've never seen a programmable DMA controller with PHB(Peripheral High-Speed Bus) access before. No, that was meant ironic. You have to search hard for a MCU without one, these days:) I am not saying this is not useful. Only that this is not something special and maybe a little hyped.

@@dieSpinnt I'm not advocating for PIO like something worth writing home about in terms of real product design. It's seems like relic from the past. Although, the fact that it is not blocking main cores could come in handy one rainy day. Sure you can code the same thing in a bunch of different ways. But it fits well in Raspberrys educational theme and is indeed an intriguing little feature in educational perspective, just something very low level to tinker (play really) with, get out of comfort zone of Wiring framework.

@@Mr.Leeroy No, sorry. I'm not blaming you. I just think it's terrible that so many others are now on the hype. Blinkers. As if there was nothing else. Programmable I/O is a very flexible and good concept. This is moving in the direction of parallelization or externalization, and there, too, the necessary caution must be exercised. Your thoughts about the Arduino / Wiring Framework? Absolutely true! Let us surprise;)