No available video device (Raspbian Stretch)

[uwe76]

Hi Zetsin,

I would like to run two graphical JavaScript applications on two separate displays. Right now, I'm using multiple Adafruit displays with a Raspberry Pi Zero W. They're registered as /dev/fb1 and /dev/fb2 via SPI and display overlays. I set an environmental variable via export SDL_FBDEV="/dev/fb1".
If I'm now running your test.js I end up with the error "No available video device" after I modified app.js slightly:

const SDL_error = require('../dep/SDL_error')
[...]
if(SDL.SDL_Init(flags) != 0) {
console.log(flags);
console.log(SDL_error.SDL_GetError());
this.quit()
return
}

Can you hint me how to use node-sdl2 with multiple dedicated framebuffer devices?

Cheers,
Uwe

[zetsin]

Hi, it seems that error is thrown by SDL2.0,
https://gist.github.com/zetsin/9d524ed07aaf974f4bb2e45bdabed3f5#file-sdl_video-c-L516

you should predefine macro SDL_VIDEO_DRIVER_RPI when compiling SDL2 lib

[uwe76]

Hi, thanks for the quick reply. Inspired by your answer I've been looking around more and found my mistake(s). For a start, Raspbian Stretch SDL2 (v2.0.5) is only supporting X11 (as you already pointed out implicitly) - not direct output via the Raspberry video driver "RPI" nor the framebuffer driver "directfb". But, before I recompile SDL2 from scratch I tried X11 instead. So, after configuring my xorg.conf to use SPI framebuffer devices and setting the correct environmental variables I was able to start your test.js :-). Thank you very much for the push in the right direction.

xorg.conf:

[...]
Section "Device"
Identifier "fbtft_dev"
Driver "fbdev"
Option "fbdev" "/dev/fb1"
EndSection
[...]

console:

export $DISPLAY=:0.0
export SDL_VIDEODRIVER=x11
node test.js

[zetsin]

It's cool. Where is your project, may I have a look? I've never developed with Raspbian, that I started to have a little bit interest in.

[uwe76]

I don't have my projects (yet) on GitHub. Until now, I'm using my own Git server; let's see what happens when Microsoft chips in to GitHub ;-) - I just registered to GitHub recently. I was using https://github.com/vesteraas/node-pitft to write some simple JavaScript thingys (like e.g. a Mario inspired jump and run) displaying some stuff on Adafruit displays. I love the low entry point and ease of use. But, because the Raspberry Pi Zero is so slow to dev/run the code I've been looking around for alternative dev options. Basically, I would like to write and test my code on a PC using an emulator or such. It's such a struggle to test any graphical output on a real Raspi + TFT display in JavaScript. It would be nice to have a separate dev environment and only go to HW when you're ready about it.