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Forum Index : Microcontroller and PC projects : what about a pico hatstand
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Quazee137 Guru  Joined: 07/08/2016 Location: United StatesPosts: 522 |
I am using the pico to HAT by Waveshare testing pants for the MM170 Hatstands. That after seeing your new board was thinking of a RPi2040 chip based Hatstand adding a 40 pin RPi header would allow for many RPi add-ons and could do the VGA/sound/game pads ect.. In away more useful that a Pico by having one base and as many plugins already for the RPi's. I have been putting off do something like this as I am so tired of building parts. Any thing new seems to need to have the parts built for Eagle. And parts build is trial-n-error have been mostly error and retry. Quazee137 edit I should have titled it "RPi-Hatstands" Edited 2023-03-21 19:39 by Quazee137 |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 5725 |
You mean like HATs that would fit onto my Raspberry Pi-coMite design? It already has a GPIO connector that is fairly close to that of a Raspberry Pi and the fixing points are the same. I've not attempted to try any, but in theory any Raspberry Pi compatible HAT that communicates using I2C or SPI and doesn't attempt to put 5V onto the pins should work if you write the MMBasic to handle it. Any that use other GPIO pins may or may not work as those particular pins may not be available. The Pico simply hasn't got enough spare IO once other stuff is in use. You can build it without the uSD card, VGA, PS2 or audio if you wish, then use a PicoMite rather than a PicoMite VGA and all those pins are available. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 3521 |
Peter's vision... This will fit 2 HAT's....  PicomiteVGA PETSCII ROBOTS |
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| Quazee137 Guru Joined: 07/08/2016 Location: United StatesPosts: 522 |
Going back a while to this hatstand Peter did this and a few others. Quazee137 |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 3521 |
Ok, you want a pi zero hat connector to a picomite. Sorry, misunderstood. There is one thing to take into account: On the VGA mite there are not many IO pins unused (10 in total, 7 digital, 3 analog/digital), and you could add to this the I2C bus (2 pins). We have to carefully plan the pins on the 40 pin (hat) header to make best use of the available hat's. Volhout Edited 2023-03-22 06:02 by Volhout PicomiteVGA PETSCII ROBOTS |
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| Quazee137 Guru Joined: 07/08/2016 Location: United StatesPosts: 522 |
Peter made 3 hatstand boards that had the RPi 40 header. I got 2 from from Micromite.org. I like MM170 but the usb connector "to hard for me to solder" So I made a version that took a 4 pin usb on module with 4 inline pins that I could remove after programing later used the HC-12 and ESP8266. Was using them till the supply chain problems. Been testing my pants I/O boards with the Waveshare "pico to hat". With the MM170 hatstand uses the Waveshare 4"LCD and under the hatstand my controller boards. Peters new board using the RPi2040 chip got me thinking if he did a hatstand using it.Bring all lines out to the 40pin like the "pico to hat" does. Then one can add a VGA/sound/game controller at the 40 pin. Yes it makes for a two board but right angle connectors makes it feel like one board. Also that makes the hatstand base more flexible for many other projects. I am trying easyEDA but Im old and have used Eagle for so long its a habit now every thing is auto mode except for making new parts with many pins. If any one has the RPi2040 chip lib that can be used with Eagle7 I'll give it a go. I am trying to see if a few customer pants boards can be allowed to go open source as the customer is no longer ordering them. I searched the forum for the threads but only found the one I posted. I saved all of peters hatstands files on a thumb drive now looking for them. well short story long Quazee137 |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 5725 |
That's almost the opposite way that I think of using a PicoMite. :) I think of having one PicoMite and dedicated boards for each job. You can then plug the Picomite into any of them. Ok, you really need a VGA and a non-VGA, but you get the general idea. A "hatstand" is only a PicoMite wired to pins, maybe with a power supply socket and/or a reset button. Everything else is out to pins and you plug on the appropriate "hat". It's not as dependent on external bits like the Microbridge as the MX170 was. In fact, put pins into a PicoMite pointing "upwards" and you have a "hatstand" already. TBH I, personally, couldn't find a use for that - it's too vague. If the "hats" are stackable then you can only use them in particular sets because of pin clash. Do you, for example, have separate "hats" for VGA, PS2 and audio just in case only one of those functions is used? Perhaps a better way is to make all "hats" I2C. The connector has 5V (in case it needs a high current), 5V GND, 3V3, 3V3 GND, SDA and SCL pins. Each "hat" makes its own arrangements after that. It could be a simple expander chip or a MX170 reading some analogue inputs into buffers. Using this system you can use another Pico as intelligent IO if you want. Several of them. :) It will work with any of the existing designs that makes an I2C port available, but you may need an adapter board to get the pins in the right positions for "hats". The adapter could simply stand alone and be connected by wires, plugged into a CMM2 for example. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 8578 |
Here is the main hatstand thread https://www.thebackshed.com/forum/ViewTopic.php?TID=10043 |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 5725 |
The full Raspberry Pi GPIO port isn't a good match to the PicoMite. I got a lot of it filled, but only by including the video, ps2 and sound pins. There's simply not enough IO on the Pico to do everything. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 8578 |
You are missing the point. The Raspberry Pi has 27 I/O pins the RP2040 has 30 (assuming you use the chip and not the Pico). If we allowed 3 for the onboard sdcard then you have a perfect match. The whole point of the "HAT" concept is that it is the hats that provide the extra capabilities. It seems like Quazee137 was the one person who took up using the original "hatstands". I could easily knock up a RP2040 version if there was sufficient interest now I have the circuit for the "bare-metal" rp2040 |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 5725 |
Oh, I got the point, that was the reason I said "PicoMite" rather than "RP2040". :) Emulating a Raspberry Pi - not just it's GPIO port - means including for SD, video, keyboard and audio (as a minimum) in addition to the GPIO, not shared. That isn't feasible even with a "naked" RP2040. Unless you are emulating the Pi there's not really a lot in bothering with its form factor as, very often, an expanded Pi doesn't fit into cases. The board I played with is closer to "the RPi experience" than a method of controlling hats. It's a usable "boot to BASIC" thing that might fit into a RPi case. "Hats" are a bit of an afterthought really. TBH I can't really see a point in plugging RPi hats onto a PicoMite. Most of them are relatively expensive for what they do and you have no software support anyway. Far better to plug them into a RPi. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Quazee137 Guru Joined: 07/08/2016 Location: United StatesPosts: 522 |
Looking around today I found a an older board I don't see it being sold any where. Pico to RPi 40 I really like his Zero Pico "Meta Pico" board just needs the 16M flash. was going to order the red board to play with the pico's I have sadly out of stock. I have the Waveshare but its form factor has a pico socket I dont need. peter can I get the easyEDA files and give it a go? Quazee137 |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 5725 |
That's a neat solution. :) I wonder if it's worth doing something similar but for one of the Pico clones with the extra flash on-board? If so, I think it might have to be that one that Peter has been using rather than the YD-RP2040 just because it seems to have a full speed flash chip. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 5725 |
I've just discovered that I have some matherp MM+ Hatstand PCBs if anyone wants one (UK only, I'm afraid - postage costs). IIRC I got them on one of my first JLCPCB orders. I've no chips for them, obviously! If I had I'd probably have attempted to build one as this was when I was playing with SMD - and I'm still *very* apprehensive about soldering chips like that, having fatally mangled one. :( Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Quazee137 Guru Joined: 07/08/2016 Location: United StatesPosts: 522 |
I now have what I need to start working on a 2040 hatstand. In looking around I also found Using SPI RAM with 2040 talk is about it being used as a frame buffer. could the LCD and VGA display make use of? another way for me would be to hold bmps of my screens and not have to redraw just use the GUI controls. some reading up with the new library flash custom csubs can also do read/write to the SPI RAM. the 23LC1024 128K by 8 is low cost and in stock at many places. one last thing I am looking at about eight "pico to RPi 40" pinouts all have different pins setup. Any thoughts Quazee137 |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 5725 |
I don't think ordinary SPI RAM is anywhere near fast enough for a frame buffer. Even the external QPI flash is too slow - it has to be RAM on the CPU bus. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 3656 |
The Pico has quite a bit of RAM. Do you really need more? SPI RAM doesn't look attractive for much! John |
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