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Forum Index : Microcontroller and PC projects : Potentially Dumb Question- Picomite VGA vs Picomite?

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jwettroth

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Joined: 02/08/2011
Location: United States
Posts: 64
Posted: 07:08am 24 Jan 2023
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I'm trying to follow all these proliferating mites.  Here is what I think I understand

The Picomite has a full featured basic and with 5.07.06 version has a robust file system.  The code in this version runs on one of the two pico processors and the second is essentially idle.

The Picomite VGA has the same basic language features as above but use the second processor and some port pins to implement a VGA output and a PS2 keyboard input.  The VGA and the KB run on the second processor so take up no resources from the main processor running the basic interpreter.

Is this correct?

Can I use the Picomite VGA and just not enable the KB and display and have a Picomite?

What is the "cost" in resources of the VGA version.  It sounds like there is no "cost" in terms of basic language execution speed.

Thanks for all you efforts all.

John
John Wettroth
 
JohnS
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Joined: 18/11/2011
Location: United Kingdom
Posts: 3034
Posted: 10:23am 24 Jan 2023
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I think broadly right but IIRC (hmm) the VGA one has smaller RAM (for user stuff) and smaller flash slots.

I don't know about execution speed. At a guess (!) no impact. It's probably plenty fast enough either way.  (You could look through the source for #ifdefs...)

John
Edited 2023-01-24 20:29 by JohnS
 
thwill

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Joined: 16/09/2019
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Posted: 10:28am 24 Jan 2023
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  JohnS said  I think broadly right but IIRC (hmm) the VGA one has smaller RAM and smaller flash slots.

I don't know about execution speed. At a guess (!) no impact. It's probably plenty fast enough either way.  (You could look through the source for #ifdefs...)

John


I don't think the PicoMiteVGA firmware can drive LCD panels.

Best wishes,

Tom
CMM2 Welcome Tape, Creaky old text adventures
 
JohnS
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Posted: 10:29am 24 Jan 2023
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  thwill said  I don't think the PicoMiteVGA firmware can drive LCD panels.

Best wishes,

Tom

I expect that's right!

I'm somewhat curious as to the reason for (the other) John's post...

John
Edited 2023-01-24 20:31 by JohnS
 
Mixtel90

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Joined: 05/10/2019
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Posted: 11:04am 24 Jan 2023
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@jwetroth

You can't use a single PicoMite for both purposes, if that's what you are thinking. The display system isn't loaded from the file system, it's built into the firmware.

The non-VGA version is designed from the ground up to handle LCD displays with or without touch screens. These displays are mostly serial (I2C or SPI) connected. Until recently there was no frame buffer, the display being updated as required, but a recent change to the firmware has created one (at least in some cases - I'm not well up on this). Both PIOs are available to the user. The CPU clock can be set to any frequency within the usable range. This version cannot drive a VGA monitor but it can handle a greater number of colours and higher resolutions.

PicoMite VGA is a little different:
One CPU core and one PIO are continually used to generate the VGA output from an area of RAM (the frame buffer). The main CPU then simply sets pixels in the frame buffer and they are automatically displayed. There is virtually no performance overhead - the VGA system is running independently.

The VGA version also has limited CPU clock speeds as these are divided down to get the correct video frequencies. You can't use, for example, a slow clock to save power.

The VGA version cannot drive other types of display. The drivers are simply not there. There are only two resolutions: 640x480 (2 colours) and 320x240 (16 colours).


A PS/2 keyboard can be connected to both systems. If it isn't required it can be disabled using OPTION KEYBOARD NO_KEYBOARD.
Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs
 
stanleyella

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Joined: 25/06/2022
Location: United Kingdom
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Posted: 03:50pm 24 Jan 2023
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I got the impression the vga version did not implement touch glcd but spi , i2c displays did graphics. Doh!
I don't know if I should try vga picomite.. seems both silly yet really cool.
A monitor and keyboard is a space investment. A glcd is just a board.
I guess vga is faster than spi glcd?
 
Mixtel90

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Joined: 05/10/2019
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Posted: 05:07pm 24 Jan 2023
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Correct, PicoMite VGA doesn't work with touch.

If you have a spare Pico and a monitor with a VGA input then why not give it a try? You can always put the non-VGA version back if you don't like it. There's hardly any hardware involved (a VGA socket and some resistors). Note that it has its own manual as some commands differ a bit. The GUI controls aren't implemented (not much point without touch!).

If you are clever you can give the illusion of 640x480 colour as each of the 40x30 "tiles" (16 pixels square) in that mode can have its own foreground and background colours independently of the others. Font 3 is also 16x16, so you can create multi-coloured text.
Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs
 
jwettroth

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Joined: 02/08/2011
Location: United States
Posts: 64
Posted: 02:33pm 25 Jan 2023
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Thanks all and especially Mick.  I hadn't considered the LCD support or the use of one PIO.  I'm sorry about the double post all, hit save and it didn't look like it took- couldn't reverse it once I noted it.  Thanks again.
John Wettroth
 
stanleyella

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Joined: 25/06/2022
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Posted: 02:49pm 25 Jan 2023
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@Mixtel90, I should try vga as I got monitors and ps2 keyboards. (hoarder :) )
I got an interest in graphics and spi displays run smooth but spi won't be as fast as vga.. I'm guessing.
It will be a new learning curve but cheap entertainment and fun seeing glcd 320x240 on vga.
The graphic buffers look interesting.

ok,  I am downloading vga for picomite soon, I got 3 but 1 is spare. not looking forward to the ps2 kb wiring.  

If it works I'll post a game, that's why I want to try it, for games/graphics.
stan.
 
Martin H.

Senior Member

Joined: 04/06/2022
Location: Germany
Posts: 228
Posted: 04:15pm 25 Jan 2023
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  stanleyella said   not looking forward to the ps2 kb wiring.  

If it works I'll post a game, that's why I want to try it, for games/graphics.
stan.

If you wouldn't get PS2 Keyboard running, you can still type in with Tera Term without trouble. Thats how I most of the Time use the Pico MiteVGA, even if I have a PS2 Keyboard connected. Just for the Luxus, that I can transfer the Files via Xterm and edit them in Notepad++ :-) So PS2 Keyboard isn't a MUST in the first place.
I wish you every success and have fun trying it out.
Cheers
Mart!n
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