DarkElvenAngel
Posts: 1915
Joined: Tue Mar 20, 2018 9:53 pm

Re: Serial terminal project

Sun Sep 12, 2021 4:16 pm

hippy wrote: Do you have a 'backup' command which allows you to easily save source code created on a PT52 on another machine ?
Not really you can take the SD card out and copy the programs that way. Since the USB port is tired up with the keyboard I could set up a file transfer with the serial UART.

DarkElvenAngel
Posts: 1915
Joined: Tue Mar 20, 2018 9:53 pm

Re: Serial terminal project

Tue Sep 14, 2021 2:21 pm

I'm thinking about spinning up a custom board for this project.

I'm sure the following features
8bit DAC VGA
SD card slot
PWM audio out
Reset button
RS 232 Serial port

There would still be free I/O I'm thinking an i²c bus could be useful, it would be nice to have a full size USB A port for the keyboard to plug in.

This board has always been in the plans the demo board was an easy to get ready to go options for starting on. I think something like this might also be useful for other projects.

What I'm not so sure about would be using a bare RP2040 or just provide pico slot. I feel like the cost of using the bare chip would out way the cost of the pico for small runs. Not to mention I've never done surface mount on such a small chip.

Any ideas? We could break the design decisions to it's own thread. I'm sure the BBC BASIC pico build could use this sore of board as well.

ejolson
Posts: 8300
Joined: Tue Mar 18, 2014 11:47 am

Re: Serial terminal project

Tue Sep 14, 2021 3:23 pm

DarkElvenAngel wrote:
Tue Sep 14, 2021 2:21 pm
I'm thinking about spinning up a custom board for this project.

I'm sure the following features
8bit DAC VGA
SD card slot
PWM audio out
Reset button
RS 232 Serial port

There would still be free I/O I'm thinking an i²c bus could be useful, it would be nice to have a full size USB A port for the keyboard to plug in.

This board has always been in the plans the demo board was an easy to get ready to go options for starting on. I think something like this might also be useful for other projects.

What I'm not so sure about would be using a bare RP2040 or just provide pico slot. I feel like the cost of using the bare chip would out way the cost of the pico for small runs. Not to mention I've never done surface mount on such a small chip.

Any ideas? We could break the design decisions to it's own thread. I'm sure the BBC BASIC pico build could use this sore of board as well.
Are there compatible flash chips that can be used on board, say about 1GB in size, so an SD card is not necessary? That would also make your board somewhat unique compared to other offerings.

trejan
Posts: 3736
Joined: Tue Jul 02, 2019 2:28 pm

Re: Serial terminal project

Tue Sep 14, 2021 3:27 pm

ejolson wrote:
Tue Sep 14, 2021 3:23 pm
Are there compatible flash chips that can be used on board, say about 1GB in size, so an SD card is not necessary?
That would be eMMC. Swappable storage is still nicer as you can easily backup your stuff.

ejolson
Posts: 8300
Joined: Tue Mar 18, 2014 11:47 am

Re: Serial terminal project

Tue Sep 14, 2021 3:30 pm

trejan wrote:
Tue Sep 14, 2021 3:27 pm
ejolson wrote:
Tue Sep 14, 2021 3:23 pm
Are there compatible flash chips that can be used on board, say about 1GB in size, so an SD card is not necessary?
That would be eMMC. Swappable storage is still nicer as you can easily backup your stuff.
Can you directly execute code from a 1GB eMMC like with the current 2MB flash?

trejan
Posts: 3736
Joined: Tue Jul 02, 2019 2:28 pm

Re: Serial terminal project

Tue Sep 14, 2021 3:43 pm

ejolson wrote:
Tue Sep 14, 2021 3:30 pm
trejan wrote:
Tue Sep 14, 2021 3:27 pm
ejolson wrote:
Tue Sep 14, 2021 3:23 pm
Are there compatible flash chips that can be used on board, say about 1GB in size, so an SD card is not necessary?
That would be eMMC. Swappable storage is still nicer as you can easily backup your stuff.
Can you execute code from a 1GB eMMC?
You mean replacing the flash used for storing code? No. The RP2040 is limited to 16MB and the protocol changes on the big parts to handle the larger addresses.

ejolson
Posts: 8300
Joined: Tue Mar 18, 2014 11:47 am

Re: Serial terminal project

Tue Sep 14, 2021 3:57 pm

trejan wrote:
Tue Sep 14, 2021 3:43 pm
ejolson wrote:
Tue Sep 14, 2021 3:30 pm
trejan wrote:
Tue Sep 14, 2021 3:27 pm

That would be eMMC. Swappable storage is still nicer as you can easily backup your stuff.
Can you execute code from a 1GB eMMC?
You mean replacing the flash used for storing code? No. The RP2040 is limited to 16MB and the protocol changes on the big parts to handle the larger addresses.
Thanks for the clarification. I was hoping that flash mapped to the 32-bit ARM address space could grow to around 1GB--sort of like a scaled down version of Intel Optane persistent memory.

https://www.intel.com/content/www/us/en ... emory.html

trejan
Posts: 3736
Joined: Tue Jul 02, 2019 2:28 pm

Re: Serial terminal project

Tue Sep 14, 2021 4:34 pm

ejolson wrote:
Tue Sep 14, 2021 3:57 pm
Thanks for the clarification. I was hoping that flash mapped to the 32-bit ARM address space could grow to around 1GB--sort of like a scaled down version of Intel Optane persistent memory.
If you're really determined then you could probably use a bigger flash in 24-bit address mode and then use the extended address register in the flash for banking. You'd need to replicate your code into each bank or have thunks in RAM to swap the bank, invalidate the XIP cache and then do a jump. All theoretical since I've not tried any of this on a RP2040. It'd be a neat "because I can" project though.

DarkElvenAngel
Posts: 1915
Joined: Tue Mar 20, 2018 9:53 pm

Re: Serial terminal project

Tue Sep 14, 2021 6:14 pm

I remember seeing chips https://blog.adafruit.com/2020/12/26/sd-card-on-a-chip/

That could be used as an option.

trejan
Posts: 3736
Joined: Tue Jul 02, 2019 2:28 pm

Re: Serial terminal project

Tue Sep 14, 2021 6:34 pm

DarkElvenAngel wrote:
Tue Sep 14, 2021 6:14 pm
I remember seeing chips https://blog.adafruit.com/2020/12/26/sd-card-on-a-chip/

That could be used as an option.
This chip would be a replacement for the existing SD card slot. RP2040 can't boot off these as the protocol used is different.

I bought some of these a while back. They do work but are a niche item.

DarkElvenAngel
Posts: 1915
Joined: Tue Mar 20, 2018 9:53 pm

Re: Serial terminal project

Tue Sep 14, 2021 6:47 pm

I was thinking it might work in tandem with an SD card not as the boot media. The chip could act as permanent storage and the SD as removable. However in the grand scheme it's more redundant than anything else. Since an SD card is cheap enough for gigabytes of space still it could have uses.

I know from this project the amount of storage available far exceeds what is needed, my understanding is that little FS wouldn't really work for this project with all the interrupts in use.

DarkElvenAngel
Posts: 1915
Joined: Tue Mar 20, 2018 9:53 pm

Re: Serial terminal project

Tue Sep 14, 2021 6:57 pm

Another idea, since this chip has reminded me would be some sort of external RAM this would be used by the internal interpreter or other programs that could make use of it and leave the internal ram for processes that need more speed. Anything that took advantage or this extra memory would not be able to run as fast however it would offer something different as an option.

DarkElvenAngel
Posts: 1915
Joined: Tue Mar 20, 2018 9:53 pm

Re: Serial terminal project

Wed Sep 15, 2021 5:18 pm

I did a mock up of the PT52 keyboard it's a work in progress
PT52-Keyboard-ver_0.png
PT52-Keyboard-ver_0.png (39.92 KiB) Viewed 817 times
i'm trying to work out were to put the L1 L2 L3 L4 LEDs

I have several unused keys still.

I did the layout on http://www.keyboard-layout-editor.com/

ejolson
Posts: 8300
Joined: Tue Mar 18, 2014 11:47 am

Re: Serial terminal project

Wed Sep 15, 2021 9:00 pm

DarkElvenAngel wrote:
Wed Sep 15, 2021 5:18 pm
I did a mock up of the PT52 keyboard it's a work in progress

PT52-Keyboard-ver_0.png

i'm trying to work out were to put the L1 L2 L3 L4 LEDs

I have several unused keys still.

I did the layout on http://www.keyboard-layout-editor.com/
As the backspace key is so small, could the rest of the layout follow Dvorak so there are fewer errors?

DarkElvenAngel
Posts: 1915
Joined: Tue Mar 20, 2018 9:53 pm

Re: Serial terminal project

Wed Sep 15, 2021 9:41 pm

ejolson wrote: As the backspace key is so small, could the rest of the layout follow Dvorak so there are fewer errors?
I had real trouble getting all the modern keys and the retro keys to all fit even now this layout is huge I think the CAD was almost 500mm the idea was to make a case that looked like the retro with the keyboard and screen all in one.


I don't see why you couldn't use Dvorak I'm going to make the keyboard with cherry MX switches and a pico for the decoder so it should be easy to do. (Famous last words)

DarkElvenAngel
Posts: 1915
Joined: Tue Mar 20, 2018 9:53 pm

Re: Serial terminal project

Thu Sep 16, 2021 4:13 am

I've refined the design a bit and did some colouring,

First was this design
PT52-Keyboard-ver_1.png
PT52-Keyboard-ver_1.png (70.96 KiB) Viewed 772 times
Then I thought about a slight rearrangement
PT52-Keyboard-ver_1a.png
PT52-Keyboard-ver_1a.png (70.65 KiB) Viewed 772 times
One day when I'm rich I could make one of these keyboards for now it might need to be something more down to earth.

hippy
Posts: 10761
Joined: Fri Sep 09, 2011 10:34 pm
Location: UK

Re: Serial terminal project

Thu Sep 16, 2021 4:50 pm

DarkElvenAngel wrote:
Thu Sep 16, 2021 4:13 am
One day when I'm rich I could make one of these keyboards for now it might need to be something more down to earth.
Indeed. Though this will initially sound harsh; you need to separate what is achievable and useful and what is flight of fantasy. Separate what you want to provide for others and where you would like to take things yourself.

Up to providing a PCB for others to use I was with you all the way. No one else AFAIK provides a board which supports 8-bit VGA, USB-A socket, SD Card and analogue out, and I believe that would serve as a good foundation for any Pico-based Home Computer, should have a wide audience and eager market.

Going to, what seems to me, a retro-style VDU with in-built screen and a dedicated keyboard narrows that audience and potential market and I can't really see the point.

I understand you want that - and that's fine. But will anyone else ?

DarkElvenAngel
Posts: 1915
Joined: Tue Mar 20, 2018 9:53 pm

Re: Serial terminal project

Thu Sep 16, 2021 5:12 pm

I totally agree, the PCB design is something achievable and would make sense to make available for others.

What doesn't make sense is the keyboard I still would love to make my replica. I have a screen most of the other parts the problem comes down a suitable case and keyboard. I bought a keyboard that fits the part as close as possible hopefully updates to TinyUSB and the SDK allow it to be useful.

I've been searching off and on for a retro computer for ages I've never had much luck finding one in working condition at a fair price. So making my own is the next best thing.

No more pie in the sky custom keyboard s for now I'm going to focus on the PCB design. Is there a PCB design suite that runs on a Pi 4 8Gb

ejolson
Posts: 8300
Joined: Tue Mar 18, 2014 11:47 am

Re: Serial terminal project

Thu Sep 16, 2021 5:25 pm

DarkElvenAngel wrote:
Thu Sep 16, 2021 5:12 pm
I totally agree, the PCB design is something achievable and would make sense to make available for others.

What doesn't make sense is the keyboard I still would love to make my replica. I have a screen most of the other parts the problem comes down a suitable case and keyboard. I bought a keyboard that fits the part as close as possible hopefully updates to TinyUSB and the SDK allow it to be useful.

I've been searching off and on for a retro computer for ages I've never had much luck finding one in working condition at a fair price. So making my own is the next best thing.

No more pie in the sky custom keyboard s for now I'm going to focus on the PCB design. Is there a PCB design suite that runs on a Pi 4 8Gb
It seems the main differentiating factor is having 8-bit as VGA rather than 15-bit.

Does this free enough GPIO to connect a keyboard without using the USB port?

I think a Pico-based keyboard computer that also functions as a programmable gaming keyboard would be a possible market niche that is currently unfilled.

DarkElvenAngel
Posts: 1915
Joined: Tue Mar 20, 2018 9:53 pm

Re: Serial terminal project

Thu Sep 16, 2021 5:53 pm

ejolson wrote: I think a Pico-based keyboard computer that also functions as a programmable gaming keyboard would be a possible market niche that is currently unfilled.
I think for that a more conservative and standardized design would work best for that maybe a 60% size, I'll leave that for someone else to design.
ejolson wrote: Does this free enough GPIO to connect a keyboard without using the USB port?
I was thinking the PS2 interface might work. You'd use 10 pins for VGA, 1 for PWM sounds, 4 for SD card. I would leave an i²c bus open and that's 2 more optional.
So 17 pin used max or 15 without i²c

DarkElvenAngel
Posts: 1915
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Re: Serial terminal project

Thu Sep 16, 2021 6:59 pm

Trying to wrap my head around KiCAD, Are there symbols I can get for the Pico and the RP2040 I install KiCAD from the repos.

I use to do this sort of work by hand so I need to learn to use KiCAD.

hippy
Posts: 10761
Joined: Fri Sep 09, 2011 10:34 pm
Location: UK

Re: Serial terminal project

Thu Sep 16, 2021 7:55 pm

DarkElvenAngel wrote:
Thu Sep 16, 2021 5:53 pm
I was thinking the PS2 interface might work. You'd use 10 pins for VGA, 1 for PWM sounds, 4 for SD card. I would leave an i²c bus open and that's 2 more optional.
I would go for two PWM audio then you may have the low-end MP3 market as well. And if you don't someone will insist they need stereo. I wouldn't worry too much about allocating I2C and SPI buses; put the ones you need on the higher numbered pins below ADC, take ADC and whatever low-numbered pins are left to an edge mounted 0.1" header.

Users always code for low-numbered pin I/O so make it easy for them. It only makes it a little more complicated for yourself.

As to whether to design for RP2040 chips or Pico or other plug-in that depends on how much you want to source and stock. There are pro's and con's each way.

My view is that DIY manufacturing and selling is a course of last resource unless already in that game. Better to get the design right and convince a manufacturer like Pimoroni or someone else to build it, stock it and sell it if you can. They will be far better placed to handle everything it involves.

I would therefore recommend getting the design right and finalised on paper before hitting KiCAD.

DarkElvenAngel
Posts: 1915
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Re: Serial terminal project

Tue Sep 21, 2021 12:41 am

I'm making a small change to the PT52 escape sequences for background and foreground colours. Since I'm defaulting to 256 colour mode. The previous method only allowed for access to a fraction of the colours. This change maintains compatible with the first 16 colours. Colour 17 was '0' so it makes sense to use 0-F case insensitive hex values so that all 256 colours can be accessed.

[ESC] b 00 would be background colour 0
[ESC] f FF would be foreground colour 256

Note the leading zero is mandatory.

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Gavinmc42
Posts: 6211
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Re: Serial terminal project

Tue Sep 21, 2021 1:25 am

Been watching lots of Mech keyboard channels.
It seems a high percentage prefer 65% keyboards.
Basically a 60% with the 4 arrows keys, some have pageup/down as well.
75% have the Function key row?

That numpad takes up too much room on desks for me, I use compacts.
No room for the development things that hang off Pi's with a full width keyboard.
I'm dancing on Rainbows.
Raspberries are not Apples or Oranges

DarkElvenAngel
Posts: 1915
Joined: Tue Mar 20, 2018 9:53 pm

Re: Serial terminal project

Tue Sep 28, 2021 8:24 pm

I've now gotten scanline building from inside the PT52 project and started my tinkering to make it 8 BPP.

So far I get read lines on the screen where the text use to be. I think I have to loose the demo board and go breadboard for this part.

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