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Forum Index : Microcontroller and PC projects : what about a pico hatstand

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Quazee137

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Joined: 07/08/2016
Location: United States
Posts: 450
Posted: 09:25am 21 Mar 2023
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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
 
Mixtel90

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Posted: 10:26am 21 Mar 2023
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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
 
Volhout
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Joined: 05/03/2018
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Posted: 12:47pm 21 Mar 2023
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Peter's vision...

This will fit 2 HAT's....



If nothing goes right ... turn left
 
Quazee137

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Posted: 02:32pm 21 Mar 2023
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Going back a while to this hatstand

 Peter did this and a few others.

Quazee137
 
Volhout
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Posted: 05:47pm 21 Mar 2023
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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
If nothing goes right ... turn left
 
Quazee137

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Posted: 02:06am 22 Mar 2023
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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
 
Mixtel90

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Posted: 08:21am 22 Mar 2023
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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
 
matherp
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Joined: 11/12/2012
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Posted: 08:28am 22 Mar 2023
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Here is the main hatstand thread

https://www.thebackshed.com/forum/ViewTopic.php?TID=10043
 
Mixtel90

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Posted: 09:03am 22 Mar 2023
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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
 
matherp
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Posted: 09:22am 22 Mar 2023
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  Quote  The full Raspberry Pi GPIO port isn't a good match to the PicoMite.


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
 
Mixtel90

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Posted: 10:33am 22 Mar 2023
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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
 
Quazee137

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Posted: 11:47pm 23 Mar 2023
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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
 
Mixtel90

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Posted: 07:39am 24 Mar 2023
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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
 
Mixtel90

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Posted: 09:25am 24 Mar 2023
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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
 
Quazee137

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Posted: 05:43pm 30 Mar 2023
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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
 
Mixtel90

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Posted: 06:12pm 30 Mar 2023
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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
 
JohnS
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Posted: 07:10pm 30 Mar 2023
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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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