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Forum Index : Microcontroller and PC projects : PicoMite: Why?

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Romeo

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Posted: 01:32pm 19 Feb 2022
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  robert.rozee said  
the first version of 'ascii ICSP' hardware was implemented using an MX150 running MMbasic ..

cheers,
rob   :-)

Thank you Sir, and to all the people here being nice enought to clarify the origin of the *mites galaxy, every newcomer as me fell sometime lost in space between all the different versions.  
 
Mixtel90

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Posted: 01:40pm 19 Feb 2022
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Now all you need to do is write the software to make it happen. :)

Using I2C, RS-232 or RS484 as an expansion bus is fine, and well within possibilities. I think even I might be able to manage that (especially as Geoff has already written a workable I2C system). Getting it to work using USB, and handling the USB at the PC end is something else - which I'll leave for someone far cleverer than I. I'm not even 100% certain that it can be done on a Pico. If it could then I'm rather surprised that no-one appears to have published a way to do it on the web.
Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs
 
JohnS
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Posted: 02:31pm 19 Feb 2022
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I expect people have, quite possibly using libusb

Maybe for the pico, maybe not, but using that will work for pretty much any USB device.

John
Edited 2022-02-20 00:33 by JohnS
 
Mixtel90

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Posted: 02:51pm 19 Feb 2022
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I've only found one similar idea, using a load of python on the Pico ( telemetrix ) and a USB connection to a Raspberry Pi. I can't see anything else other than that. There seems to be servers for other platforms (including windows) but I think you have to program in python on them.
Edited 2022-02-20 00:56 by Mixtel90
Mick

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lizby
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Joined: 17/05/2016
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Posted: 02:59pm 19 Feb 2022
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  thwill said  @lizby is working on his tan and building a new shed

By mid-February, too hot already in Crystal River, Florida, to be working on a tan (other than a farmer's or carpenter's tan), but the solar shedlet is coming along.


 
I'll soon be done with construction and can start putting together my solar gear. MMB4L on the PiZW may be involved. (And then I may be able to get back to MMB4L development.)

  Mixtel90 said  porting MMBasic to a platform with moving goalposts seems pointless.

That's the actual point. MMB4L is a +Linux+ implementation, and both sysfs and libgpiod are Linux GPIO implementations not specific to the pi.

Obviously, as with any Linux device, those who are implementing the Linux port have to put in the connections between the physical hardware and the sysfs or libgpiod routines, but that is already done in the pi OS releases and there's no reason to think that it will not continue to be done in the future.

Now graphics will be a different matter, at least for the time being.
 
lizby
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Posted: 03:11pm 19 Feb 2022
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  Romeo said  
  robert.rozee said  the first version of 'ascii ICSP' hardware was implemented using an MX150 running MMbasic ...

Thank you Sir, and to all the people here being nice enought to clarify the origin of the *mites galaxy, every newcomer as me fell sometime lost in space between all the different versions.


Here's a list from Micromite MMBasic Libraries: Maxi/MicroMite variations: MaxiMite, Colour MaxiMite (CMM/CMM1), MX150 MicroMite (MM1), MX170 MicroMite (MM2), MX470 MicroMite Plus (MM+),  PIC32MZ MicroMite eXtreme (MMX), MMBasic for DOS, Pi-cromite (pi-based, no longer supported, may work for non-gpio uses), Armmite H7, Armmite L4, Armmite F4, Colour Maximite 2 (CMM2), Picomite, MMB4L (Linux--currently in Alpha), VGAMite, MMB4W--currently in Alpha.

(If I've missed anything, please post about it.)
 
Phil23
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Joined: 27/03/2016
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Posted: 10:27pm 19 Feb 2022
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  Phil23 said  Interesting,

I've ended up on this thread after looking on RicTech for a Display/IO interface type board.....

Is there any mention of a Pi Zero Backpack rehash?


I may have been misunderstood.

I mean't something similar to what's on Grog's site for the Zero, but for the Pico instead.

I'm aware that the Pi Zero days have finished.
 
Mixtel90

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Posted: 11:01pm 19 Feb 2022
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Sorry, I'm not familiar with what Grogster did. I did a PicoMite backpack to fit the ILI9341 some time ago. Is that the sort of thing you meant?
Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs
 
Grogster

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Posted: 11:20pm 19 Feb 2022
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@ Phil23: Yes, that is what my board is supposed to be.  A similar kind of arrangement using a single Pico module, and allowing for either an EastRising type SSD1963 display, or the more common 40-pin female connector type.

I just need to find some time to get it finished, but Mixtel90 has made very rapid progress in that department, so he'd be the best one to ask, as he has finished designs he might be able to offer.

I will finish that board of mine at some point, but it is considered low-priority against the current to-do list at work.
Smoke makes things work. When the smoke gets out, it stops!
 
Mixtel90

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Posted: 07:22am 20 Feb 2022
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I have a 5" SSD1963 40-pin design, Phil, but it's still in the prototype stage really. The first prototype boards are in the post to me (from China). Some details here.
Edited 2022-02-20 17:26 by Mixtel90
Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs
 
Phil23
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Posted: 09:06am 21 Feb 2022
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  Mixtel90 said  I have a 5" SSD1963 40-pin design, Phil, but it's still in the prototype stage really.


Was thinking on a bit more basic level, circa the 2.8" screen of the original backpacks, but with the better performance & additional IO pins.

All pins currently consumed on a project based on that package.
 
Volhout
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Posted: 09:47am 21 Feb 2022
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There are different application levels

Simple and Basic: picomite/micromite with IL9341 SPI
Better graphics: Mixtels picomite+SSD1963+picomite(IO)+micromite(IO) or MMX or ArmmiteF4/H7

When IOT connectivity is required, you need something like windows or linux

MMB4W with (USB-serial) attached IO expander (picomite/micromite/arduino)
MMB4L with (USB-serial) attached IO expander (picomite/micromite/arduino)
PicRomite (obsolete) has IO build in

For remote IO I have succesfully used arduino's with tinybasic, but there is not reason why picomite could not be used identically. All commands that can be executed from the command line can be directly controlled from MMB4W and MMB4L. Simply serial send "Setpin 23,dout" and "pin(23)=1" and you are controlling an IO pin.
On picomite the USB connection is very fast, so not reason to implement more complex protocols that tokenize commands. Simply stream commands as if they where typed in from the keyboard.
When more advanced functions are needed, you can simply send "flash load 1" and "run", where flash slot 1 contains your written complex basic function.

No software has to be written, nothing is keeping you from exploiting what we have.

Volhout
If nothing goes right ... turn left
 
Mixtel90

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Posted: 10:27am 21 Feb 2022
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Like this, Phil?
https://www.thebackshed.com/forum/ViewTopic.php?TID=13981&P=5
About half way down Tom has posted a pic of the back of my ILI9341 backpackfor the PicoMite. All GPIO pins from 0 to 13 and GP26-28 are available for the user. GPI0-13 are on the connector along the bottom, ADC pins are on the yellow connector.
Manual for the above
Edited 2022-02-21 20:31 by Mixtel90
Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs
 
Phil23
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Posted: 08:40pm 23 Feb 2022
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  Mixtel90 said  Like this, Phil?
https://www.thebackshed.com/forum/ViewTopic.php?TID=13981&P=5


That's more what I'm thing.
ESP01? I currently have them on all my console outputs.
That & HC-12's on Com1.

Noticed that the Pico has no 5V tolerant pins, that may be an issue with the flow sensors I use. HC-12's too maybe.

Other things driven are relay blocks, active low so not sure if the 5V issue comes into play there also.

DS18B20's as well on a single bus with a 5V pull-up.
 
Mixtel90

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Posted: 10:13pm 23 Feb 2022
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One of the things you have to watch on the PicoMite is the output current limitation. It's a pretty stingy device.

From the manual:
  Quote  The maximum voltage that can be applied to any I/O pin is 3.6V.
As outputs all I/O pins can individually source or sink a maximum of 12mA. At this load the output voltage
will sag to about 2.3V. A more practical load is 5mA where the output voltage would typically be 3V. To
drive a red LED at 5mA the recommended resistor is 220R. Other colours may require a different value.
The maximum total I/O current load for the entire chip is 50mA.


Personally I wouldn't load an output pin to more than 2 or 3mA normally. That way you make the most of the 50mA total. It's enough for modern LEDs.

If your relay inputs have pullup resistors to over 3V6 then you'll need a driver transistor or mosfet to avoid over-voltage damage to the PicoMite.

DS18B20 will need to be run from 3V3 or level shifted.

HC12 is 3V2 to 5V5 so it's ok on 3V3. Control/data pins are ok for 3V3.
Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs
 
Grogster

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Posted: 01:40am 24 Feb 2022
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@ Phil23 - Just use some of those MOSFET-based level-shifting modules to convert from/to 5v to/from 3v3.

Link to four-channel bi-directional level-shifter module.

US$2

Even if you needed to convert several pins on the PM to 5v, these are cheap and work beautifully.

If you KNOW you only need to level-shift in ONE direction, then these are even cheaper at AU$4.60 for FIVE modules, or 92 cents of your Aussie money each.

Directional level-shifter modules.

@ Mixtel90 - have you actually run HC12's at 3v3?  3v2 is the minimum, leaving only 100mV headroom, and I have found HC12's to be very unstable at 3v3 personally, and I never run them at anything other then 5v on all my boards.  You may have had better luck then I though!  
Smoke makes things work. When the smoke gets out, it stops!
 
Mixtel90

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Posted: 07:44am 24 Feb 2022
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No, admittedly I haven't. I was going off the data sheet (which isn't always a good thing, I know). I would have expected a slight drop in output but not instability. That's naughty.

The level shifters are excellent and, to get OC outputs that will easy work with active low relay modules a 2N7000 mosfet will be ok. No gate resistor needed if it's close to the PicoMite (although I'd recommend a high value pull-down resistor to make sure the relay is normally off). You get signals that are high to operate, which I'd regard as a bonus. :)
Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs
 
Grogster

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Posted: 06:48am 25 Feb 2022
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I think that PERHAPS my issues with the HC12 @ 3v3, was during transmission.
That puts a temporary load on the supply, and if it is unable to cope(perhaps not enough decoupling caps), and the supply dips 100mV even for a moment, it is enough to cause a brown-out type effect, which then probably crashes the MCU on the module and results in odd behaviour.  I've never ever had a problem if I just run them at 5v.
Smoke makes things work. When the smoke gets out, it stops!
 
Mixtel90

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Posted: 07:52am 25 Feb 2022
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@Phil23

What I/O are you looking for? Would a second piggy-back PCB fitting between the display and my backpack be enough, do you think? Or maybe a custom version? I'd need to know what you want exactly.
Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs
 
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