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stanleyella

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Joined: 25/06/2022
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Posted: 05:09pm 15 May 2023

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I thought about using the vga keyboard with glcd picomite for buttons cos it works but full size kb, lot of space.
I got a mini usb/wifi cheap fullish kb... with laser pointer but not mmbasic compatible. I'd like a way to convert vga to composite as I got some small screens that only have composite. I'm thinking of mini picomite and vga screen cheap.
I have dvi from raspberry pi to vga converter but not the other way and think some are bogus.
Cheap avi screens from charity shop, one is a meant to be a photo viewer, other an analogue tv.

Mixtel90

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Posted: 05:11pm 15 May 2023

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https://www.ebay.co.uk/b/Vga-To-Av-Cable/158840/bn_7023555634

Mick

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

stanleyella

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Posted: 05:29pm 15 May 2023

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Wouldn't it be nice to use these cheap mini kbs with touch mouse with mmbasic?

stanleyella

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Posted: 05:31pm 15 May 2023

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Mixtel90 said https://www.ebay.co.uk/b/Vga-To-Av-Cable/158840/bn_7023555634

but are they passive bogus, b/w at best? any personal experience boss?
edit- I meant with mmbasic. I searched for circuits to build and lots use chips and youtube saying the cheap adaptors are rubbish so wary. don't want to spend lots as defeats the idea. thinking of hand held mini pico laptop?
Edited 2023-05-16 03:46 by stanleyella

Mixtel90

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Posted: 06:27pm 15 May 2023

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VGA is analogue, so is AV. I doubt if there's anything to gain using an active adapter over a passive one. MMBasic doesn't care what the video is - it's always a simple 4-bit binary number feeding a resistor network to get analogue video, Hsync and Vsync.

The weakest point will be the AV input circuitry of the display. They are often rough.

Mick

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

stanleyella

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Posted: 07:15pm 15 May 2023

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I ordered https://www.ebay.co.uk/itm/266246510423
so cheap, will it work??

stanleyella

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Posted: 07:26pm 15 May 2023

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Mixtel90 said VGA is analogue, so is AV. I doubt if there's anything to gain using an active adapter over a passive one. MMBasic doesn't care what the video is - it's always a simple 4-bit binary number feeding a resistor network to get analogue video, Hsync and Vsync.

The weakest point will be the AV input circuitry of the display. They are often rough.

does that mean picomite vga could just be composite v & h sync and video from the signals but different circuit to vga... and then convert to composite.?
not a prob, will wait to see adaptor working. Mini vga displays not cheap.

Volhout
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Posted: 09:38pm 15 May 2023

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Analog video is interlaced video at 15.6 kHz. VGA is non interlaced, at 31kHz. These are not compatible, you need to frame grab the vga, convert rgb to yuv, and play it back with a different speed and line order.
Then create combined hsync/vsync, phase modulate the color signals u and v.

There are chips that do this, but it is not something the pico can do with simple resistors. You need analog chips for the analog part, the modulation)

Volhout
Edited 2023-05-16 07:39 by Volhout

PicomiteVGA PETSCII ROBOTS

stanleyella

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Posted: 04:43pm 16 May 2023

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Good info Volhout, thanks. I think the vga adaptor I ordered will not have composite video, just the vga signals. doh :(
I have a rpi 1,2,3 video out to vga which worked and usable so think vga to composite should be ok to. searching for circuits that are cheap, I would like a composite video option so get vga graphics on small CHEAP screen.

thwill

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Joined: 16/09/2019
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Posted: 10:00am 07 Jun 2023

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Hi folks,

It still needs some titivating, but courtesy of @bigmik's PCB skills and with a little help from @Turbo46 and others:

Final(?) schematic and gerbers will follow once the kinks have been ironed out.

Best wishes,

Tom
Edited 2023-06-07 20:01 by thwill

Game*Mite, CMM2 Welcome Tape, Creaky old text adventures

Volhout
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Posted: 10:07am 07 Jun 2023

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Hi Tom,

Very nice !! And it already plays 2 games !!

Volhout

PicomiteVGA PETSCII ROBOTS

lizby
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Joined: 17/05/2016
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Posted: 12:09pm 07 Jun 2023

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Looking good, Tom--congrats.

PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed

Mixtel90

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Posted: 01:14pm 07 Jun 2023

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That's really nice! :) Good work, Tom!

Mick

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

thwill

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Posted: 01:23pm 07 Jun 2023

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Thanks folks, I think the plaudits go to @bigmik; left to my own devices I would have been another 12-18 months to produce a PCB and even then the layout would not have been good.

Volhout said And it already plays 2 games !!

PicoVaders is @Martin H's work, I'm still messing with it to get the best behaviour on the Bintendo.

Porting from the PicoMiteVGA to the Bintendo isn't trivial because the standard PicoMite firmware which the Bintendo runs doesn't have the same sprite support*. I'm hopeful I can implement an approximation of the missing bits as CSUBs, perhaps even by repurposing Peter's code from the PicoMiteVGA.

* Though PicoVaders is simpler as Martin didn't use the sprite support ... it may not have been present when he started writing it.

Best wishes,

Tom
Edited 2023-06-07 23:25 by thwill

Game*Mite, CMM2 Welcome Tape, Creaky old text adventures

matherp
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Posted: 01:49pm 07 Jun 2023

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Quote approximation of the missing bits as CSUBs, perhaps even by repurposing Peter's code from the PicoMiteVGA.

The reason I haven't implemented sprites is that they rely on reading the LCD controller's framebuffer. This is too slow to be useful on SPI displays. It is OKish on SSD1963 displays but even on these it really needs 16-bit parallel rather than 8 as supported on the PicoMite.

thwill

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Posted: 02:09pm 07 Jun 2023

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matherp said The reason I haven't implemented sprites is that they rely on reading the LCD controller's framebuffer. This is too slow to be useful on SPI displays. It is OKish on SSD1963 displays but even on these it really needs 16-bit parallel rather than 8 as supported on the PicoMite.

Hi Peter, thanks for commenting, I'm not asking for you to implement anything.

Don't we have a pair of 16-colour RAM framebuffers now ?

I still haven't measured how long it takes to blit the entire display (or a good proportion of it) from RAM to the ILI9341 but it's on my TODO list.

EDIT: Looks like it is about 14 fps if I'm measuring correctly, that's not completely awful:

t = Timer
FRAMEBUFFER Create
FRAMEBUFFER Write F
Dim colours%(4) = (RGB(Red),RGB(Green),RGB(Blue),RGB(Yellow),RGB(Cyan))
For i% = 1 To 100
For j% = 0 To 4
Box 0,0,320,240,,colours%(j%),colours%(j%)
FRAMEBUFFER Copy F,N
Next
Next
Print 1000 / ((Timer - t) / 500)

Best wishes,

Tom
Edited 2023-06-08 00:26 by thwill

Game*Mite, CMM2 Welcome Tape, Creaky old text adventures

stanleyella

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Joined: 25/06/2022
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Posted: 05:19pm 07 Jun 2023

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That is very neat. Well done. ... I prefer buttons to. I used the analogue pad and works much better than touch.

Mixtel90

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Posted: 05:48pm 07 Jun 2023

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I've just had a 1.80UKP analogue joystick working today. Not too bad at all, scaling the axis from 0-100 with 50 at midpoint or using it as a digital joystick. It's very promising.

Mick

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

ice2642

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Joined: 27/05/2023
Location: Brazil
Posts: 82

Posted: 12:30am 08 Jun 2023

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Very cool project, congratulations!

Best Regards,

MMBasic 5.0707 on PicoMite VGA

Volhout
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Posted: 02:42pm 08 Jun 2023

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Tom,

I have been playing with sound on the VGA picomite, and have oe observation I would like ot share.

The sound suffers from PRINT statements.
Te print statements go to the USB interface (console), and I think that USB stack has impact on audio. Only after I removed the last PRINT statement (change to a TEXT statement) the audio was flawless on 126MHz CPU.

Volhout
Edited 2023-06-09 00:44 by Volhout

PicomiteVGA PETSCII ROBOTS

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