8 ms·

VGA driver using PIO and DMA on the RP2040

67 points by vha3 3y ago

_Microft 3y ago
OT but a question I'm curious about: what features would people who have a lot of experience with the RP2040 like to see on a successor?
- cdcarter 3y ago
  Another pair of PIO blocks (and two more DMA channels) is my desire. I think a lot of people would love to see a (slightly more expensive) variant with more uncommitted GPIOs. My pet projects with the Pico and clones involve interfacing with an 8-bit processor, and the RP2040 just doesn’t expose enough pins for the full data, address, and control busses AND actually doing something interesting with the outside world. Another dedicated USB PHY peripheral would also be great, a lot of people lose a PIO block to adding a second USB port. Obviously this also shows the power of PIO, but it’s nice to be able to reserve those blocks for more obscure physical things. I bet a lot of people would like more analog pins, the Teensy provides a lot more, for example.
- happycube 3y ago
  I haven't done a lot per se, but 480Mb USB would be nice.
  - deleted 3y ago
    [deleted]
  - duskwuff 3y ago
    USBHS is fairly hard to support without an off-chip transceiver. There's a reason why most low-cost microcontrollers are USBFS only.
- vardump 3y ago
  Memory mappable PSRAM support would be nice. Or more pins and more PIO as well. I guess more SRAM wouldn't hurt either.
- polpo 3y ago
  More than 32 instructions per PIO block: my main current project (PicoGUS) uses 32 instructions on one PIO block and 31 on the other to handle ISA IO, ISA DMA, I2S audio out, and SPI PSRAM access. Having more would let me cut a few less corners in how ISA is handled. More/more flexible PIO instructions: branching is very limited, you can only arbitrarily SET up to 5 pins or pindirs at once (increasing to 8 would be a godsend), stalling with a sideset repeatedly executes the sideset, etc... I could go on. Memory mapped PSRAM: I made a library to assist with accessing SPI PSRAM but it's still just functions to get/set groups of bytes. An intelligent cache around it would also mitigate the much higher latency of accessing PSRAM as well. More SRAM: everyone can always use more RAM! More GPIOs: everyone can always use more GPIOs!
- CarVac 3y ago
  One more core, one more PIO, and more SRAM.
- mtreis86 3y ago
  Better power consumption, especially in deep sleep. Make waking up cheap too, especially for some IOT purposes, like grabbing a sensor reading every couple minutes and storing it in a queue for future burst transmission. Optimize for that sorta thing. Measure in nanoamps.
- claxo 3y ago
  A DAC, at least 12 bits
boricj 3y ago
This reminds me of the Uzebox [1], a video game console based on an ATMega644, but the RP2040 in this looks far more powerful at a glance. How far could this realistically be pushed? [1] https://uzebox.org/ https://uzebox.org/
- vardump 3y ago
  At least this far. https://www.youtube.com/watch?v=eDVazQVycP4 https://www.youtube.com/watch?v=eDVazQVycP4 RP2040 running Doom, includes VGA, Adlib emulation, PCM sound effects, 4 player "LAN". Pretty much the same experience as Doom on a DOS PC. 264 kB of total RAM is the main restriction.
andrewstuart 3y ago
Related: Adafruit Feather RP2040 with HDMI Output Port https://youtu.be/Nsvf5gnYErs https://youtu.be/Nsvf5gnYErs https://www.adafruit.com/product/5710 https://www.adafruit.com/product/5710 Generating PAL https://hackaday.com/2023/01/24/generating-pal-video-with-a-heavily-overclocked-pi-pico/ https://hackaday.com/2023/01/24/generating-pal-video-with-a-...
- raphlinus 3y ago
  I have the Adafruit DVI board and have been hacking on it some. It's more fun than should be allowed. There's a project to get this running using Rust[1]. Currently it outputs the blue channel with sync, but has trouble with the other two channels. I don't have a hardware lab with scope, logic analyzer, etc., so it's not easy for me to debug. In the meantime, I've been doing some experiments in the C codebase as well[2], mostly in the direction of proportionally spaced bitmap text, using the fonts in the X11 distribution. [1]: https://github.com/DusterTheFirst/pico-dvi-rs https://github.com/DusterTheFirst/pico-dvi-rs [2]: https://github.com/Wren6991/PicoDVI/pull/48 https://github.com/Wren6991/PicoDVI/pull/48
  - andrewstuart 3y ago
    Be nice if the board had wireless built in, though I believe adafruit provides a clip on wireless module.
vinkelhake 3y ago
Here's another [1] project that does VGA output from an RP2040 (the project also includes some game). There's also some support for VGA in the pico_extras [2] repo. [1] https://kilograham.github.io/rp2040-doom/ https://kilograham.github.io/rp2040-doom/ [2] https://github.com/raspberrypi/pico-extras/tree/master/src/common/pico_scanvideo https://github.com/raspberrypi/pico-extras/tree/master/src/c...
macjohnmcc 3y ago
The PicoMite VGA project does something like this as well but has the added benefit of having a very full featured BASIC interpreter built in. https://geoffg.net/picomitevga.html https://geoffg.net/picomitevga.html
djmips 3y ago
2021

67 points by vha3 3y ago

OT but a question I'm curious about: what features would people who have a lot of experience with the RP2040 like to see on a successor?

cdcarter 3y ago
Another pair of PIO blocks (and two more DMA channels) is my desire. I think a lot of people would love to see a (slightly more expensive) variant with more uncommitted GPIOs. My pet projects with the Pico and clones involve interfacing with an 8-bit processor, and the RP2040 just doesn’t expose enough pins for the full data, address, and control busses AND actually doing something interesting with the outside world. Another dedicated USB PHY peripheral would also be great, a lot of people lose a PIO block to adding a second USB port. Obviously this also shows the power of PIO, but it’s nice to be able to reserve those blocks for more obscure physical things. I bet a lot of people would like more analog pins, the Teensy provides a lot more, for example.
happycube 3y ago
I haven't done a lot per se, but 480Mb USB would be nice.
- deleted 3y ago
  [deleted]
- duskwuff 3y ago
  USBHS is fairly hard to support without an off-chip transceiver. There's a reason why most low-cost microcontrollers are USBFS only.
vardump 3y ago
Memory mappable PSRAM support would be nice. Or more pins and more PIO as well. I guess more SRAM wouldn't hurt either.
polpo 3y ago
More than 32 instructions per PIO block: my main current project (PicoGUS) uses 32 instructions on one PIO block and 31 on the other to handle ISA IO, ISA DMA, I2S audio out, and SPI PSRAM access. Having more would let me cut a few less corners in how ISA is handled. More/more flexible PIO instructions: branching is very limited, you can only arbitrarily SET up to 5 pins or pindirs at once (increasing to 8 would be a godsend), stalling with a sideset repeatedly executes the sideset, etc... I could go on. Memory mapped PSRAM: I made a library to assist with accessing SPI PSRAM but it's still just functions to get/set groups of bytes. An intelligent cache around it would also mitigate the much higher latency of accessing PSRAM as well. More SRAM: everyone can always use more RAM! More GPIOs: everyone can always use more GPIOs!
CarVac 3y ago
One more core, one more PIO, and more SRAM.
mtreis86 3y ago
Better power consumption, especially in deep sleep. Make waking up cheap too, especially for some IOT purposes, like grabbing a sensor reading every couple minutes and storing it in a queue for future burst transmission. Optimize for that sorta thing. Measure in nanoamps.
claxo 3y ago
A DAC, at least 12 bits

boricj 3y ago

This reminds me of the Uzebox [1], a video game console based on an ATMega644, but the RP2040 in this looks far more powerful at a glance. How far could this realistically be pushed? [1] https://uzebox.org/ https://uzebox.org/

vardump 3y ago
At least this far. https://www.youtube.com/watch?v=eDVazQVycP4 https://www.youtube.com/watch?v=eDVazQVycP4 RP2040 running Doom, includes VGA, Adlib emulation, PCM sound effects, 4 player "LAN". Pretty much the same experience as Doom on a DOS PC. 264 kB of total RAM is the main restriction.

andrewstuart 3y ago

Related: Adafruit Feather RP2040 with HDMI Output Port https://youtu.be/Nsvf5gnYErs https://youtu.be/Nsvf5gnYErs https://www.adafruit.com/product/5710 https://www.adafruit.com/product/5710 Generating PAL https://hackaday.com/2023/01/24/generating-pal-video-with-a-heavily-overclocked-pi-pico/ https://hackaday.com/2023/01/24/generating-pal-video-with-a-...

raphlinus 3y ago
I have the Adafruit DVI board and have been hacking on it some. It's more fun than should be allowed. There's a project to get this running using Rust[1]. Currently it outputs the blue channel with sync, but has trouble with the other two channels. I don't have a hardware lab with scope, logic analyzer, etc., so it's not easy for me to debug. In the meantime, I've been doing some experiments in the C codebase as well[2], mostly in the direction of proportionally spaced bitmap text, using the fonts in the X11 distribution. [1]: https://github.com/DusterTheFirst/pico-dvi-rs https://github.com/DusterTheFirst/pico-dvi-rs [2]: https://github.com/Wren6991/PicoDVI/pull/48 https://github.com/Wren6991/PicoDVI/pull/48
- andrewstuart 3y ago
  Be nice if the board had wireless built in, though I believe adafruit provides a clip on wireless module.

vinkelhake 3y ago

Here's another [1] project that does VGA output from an RP2040 (the project also includes some game). There's also some support for VGA in the pico_extras [2] repo. [1] https://kilograham.github.io/rp2040-doom/ https://kilograham.github.io/rp2040-doom/ [2] https://github.com/raspberrypi/pico-extras/tree/master/src/common/pico_scanvideo https://github.com/raspberrypi/pico-extras/tree/master/src/c...

macjohnmcc 3y ago

The PicoMite VGA project does something like this as well but has the added benefit of having a very full featured BASIC interpreter built in. https://geoffg.net/picomitevga.html https://geoffg.net/picomitevga.html

djmips 3y ago

2021