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Forum Index : Microcontroller and PC projects : PicoMite - composite video output
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Nimue Guru  Joined: 06/08/2020 Location: United KingdomPosts: 367 |
I suspect I know what that is before I even look at it -- many many a rainy lunchtime playing that..... N Entropy is not what it used to be |
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| Nimue Guru Joined: 06/08/2020 Location: United KingdomPosts: 367 |
I tried Serial Term and it "just didn't work" on the Chromebooks I had access to. It seemed to suffer from the "connect OK, but screens just dont update" kind of issue. A job for tonight. N Entropy is not what it used to be |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 3551 |
You would have to run the VGA at 50Hz though. And interlace the video lines ? Or does the AD724 skip the odd lines in the odd frame, and even lines in the even frame of a progressive scan VGA signal ? PicomiteVGA PETSCII ROBOTS |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 3551 |
@Nimue, Is your focus on introducing hardware (picomite / picomiteVGA) so kids can play with LED's and stuff ? Or are you focussed on introducing BASIC (MMBasic) into schools ? When the focus is on MMBasic, you could have a lower entry level with MMB4W (MMBasic for Windows). Simply install on a W10 PC and you are done. Including the graphics capabilities of the higher end CMM2 machine. And that would also work on a chromebook (gadgetjack response) see this thread: https://www.thebackshed.com/forum/ViewTopic.php?FID=16&TID=15076#190177 Volhout Edited 2022-08-16 00:20 by Volhout PicomiteVGA PETSCII ROBOTS |
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| Nimue Guru Joined: 06/08/2020 Location: United KingdomPosts: 367 |
It's neither and both - sorry to be vague. Let me explain. The new curriculum here in Wales has made aspects of computer science - mandatory for all school children from this September. The details are complex, but for primary teachers this means they must be able to program in Scratch and then move to Python (or other - MMBasic). They must also couple this coding with accessing physical hardware - control LEDs, read temperature sensors etc -- culminating with the vague statment of "design with purpose" which we (the advisors) are interpreting as design in hardware and code something that will turn on a fan when the temp is above X and its night time. All the above is a perfect use case for PicoMite and MMBasic. It can be done in Python, but that involves coding on a PC and "sending" the code to the Pi. What sells the PicoMite to schools is that to them (using serial) it is like the code is already on the Pi -- they can even see a file listing. I have just fired up a Chromebook and managed to get an acceptable use for Serial Term -- the only things not functioning are the VT100 colours and the backspace in Chromebook needs CTRL-Backsapce to function. That and the Function keys dont exist on Chromebook -- but you can tweak that one. N Entropy is not what it used to be |
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| Nimue Guru Joined: 06/08/2020 Location: United KingdomPosts: 367 |
OPTION COLOURCODE ON -- RTFM ;-) Entropy is not what it used to be |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 5735 |
You may find that the first 8 or 16 VT100 colour codes work, but not the extended ones. There are a couple of different escape code sequences for colours. For foreground colours ESC[..m may work, where .. is: 30 - black 31 - red 32 - green 33 - yellow 34 - blue 35 - magenta 36 - cyan 37 - white 90 - grey Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Nimue Guru Joined: 06/08/2020 Location: United KingdomPosts: 367 |
Thanks all -- getting there. Now to fix the need for CTRL-backspace --- must be sending the wrong ESC somehow. N Entropy is not what it used to be |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3016 |
With Serial Term installed, I plugged in a PicoMite, clicked the 3 bars, selected "Pico (/dev/ttyACM0), set baudrate, data bits, parity, and stop bits, and clicked to get the "Connected" icon and text. And I have the ">" prompt and a response to PRINT "Hello". Thanks. PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| Nimue Guru Joined: 06/08/2020 Location: United KingdomPosts: 367 |
 Does your backspace function as expected -- I seem to need CTRL-Backspace -- seems to be a know thing in Chromebooks that use the underlying hterm (or something like that). N Entropy is not what it used to be |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3016 |
Following your suggestion, I used Ctrl-Backspace (having previously found that Backspace is Delete in other apps). Oddly, that backspaces correctly on the screen, but the PRINT statement still shows the backspaced character. Print "Helllo" with a backspace after the 3rd "l" prints "Helll o". PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| Nimue Guru Joined: 06/08/2020 Location: United KingdomPosts: 367 |
I dont seem to get that, just need CTRL-Backspace. I'm using 56k baud.. N Entropy is not what it used to be |
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thwill Guru Joined: 16/09/2019 Location: United KingdomPosts: 3848 |
For the benefit of future visitors can I suggest starting a new thread specifically about the use of ChromeOS as a serial terminal. Best wishes, Tom Game*Mite, CMM2 Welcome Tape, Creaky old text adventures |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3016 |
Mick--any interest in adding that AD724 composite circuit to your PicoStick instead of the 15-pin socket?  ~ Edited 2022-08-16 01:52 by lizby PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 8592 |
Please don't - it does need firmware changes to make it work at the right frequency. Would do it for school use but not as a "might be nice-to-have" Edited 2022-08-16 02:18 by matherp |
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| Nimue Guru Joined: 06/08/2020 Location: United KingdomPosts: 367 |
I cant do the request justice - so even though I raised this, not worth the time / effort for me --- in my naivety I thought it would be a few timing tweaks and a couple of resistors. Sorry for the noise. N Entropy is not what it used to be |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 5735 |
I'll leave it alone unless there's firmware support. There wouldn't be any point. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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Rickard5 Guru Joined: 31/03/2022 Location: United StatesPosts: 328 |
Plese let me Preface this by saying, I'm just an Unruly Colonist, If the Picomite is properly Evangelized it could very well be the Arduino Killer YES, But as long as there is a Labor Government and the Geniuses at The BBC, Poor little British Boy and Girls will be tortured with the Microbit and Useless "code editors" like Scratch and Microsoft Make Code! I have a Private conspiracy theory About the Evil Plans of the BBC and their "Accidental" Bliss Inducing Shows like the Royle Family, Shameless, Faulty Towers, Dave Allen, and anything with Frankie Howard to suck us in to their Evil plans Only to Quickly Kill them to torture us for 50+ Years with Coronation Street and BBC 1 I turned the volume on the monitor to max and could hear sound. Thanks Stanleyella |
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phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 1790 |
The 50Hz / 60 Hz issue may not be such a problem. Most screens new enough to have HDMI, VGA and Composite input are smart enough to sense and adapt to 50 or 60Hz composite input as well as PAL / NTSC (by detecting the colour carrier frequency). Here I haven't seen a TV made in the last decade or two that can't do this. They are made for the whole world market. Edit Going senile. Forgot about line interlacing, composite uses it but the PicoMiteVGA probably uses progressive scanning. It is possible that some screens could detect it and adjust, but you need every one to work. An external VGA to Composite converter would need a frame buffer to do this. I think the chip shown above needs an interlaced input, which a computer can provide through the graphics settings. I imagine it would be a lot of work to change the firmware to get the odd lines on one field and even lines on the next to make a 25 or 30Hz frame rate. And if memory serves, to get the two fields to mesh into a frame the first field needs to start and end halfway through its first and last lines. Otherwise they just overlap. This was all done with just a couple of valves but now needs a chip with tens of thousands of transistors! Edit 2 From AD724 the data sheet. "Displaying VGA Output on a TV The AD724 can be used to convert the analog RGB output from a personal computer’s VGA card to the NTSC or PAL television standards. To accomplish this it is important to understand that the AD724 requires interlaced RGB video and clock rates that are consistent with those required by the television standards. In most computers the default output is a noninterlaced RGB signal at a frame rate higher than used by either NTSC or PAL. Most VGA controllers support a wide variety of output modes that are controlled by altering the contents of internal registers. It is best to consult with the VGA controller manufacturer to determine the exact configuration required to provide an interlaced output at 60 Hz (50 Hz for PAL)." Edited 2022-08-16 18:15 by phil99 |
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led-bloon Senior Member  Joined: 21/12/2014 Location: AustraliaPosts: 203 |
Composite video (B/W only) using 2 GPIO pins + 2 resisters thanks to Alan Reed Implementing Composite Video His example of a stand-alone game of pong using 1 pio block and 2 state machines. I had to "fix" his CMakeLists.txt file for my RaspberryPi setup and once tested on a Pico I moved across to the Seeed XIAO with subsequent changes to the GPIO pins used. In all, a solid display and a "cute" version of pong (no sound!!)   led Miss you George |
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