Hardware Idea - Axo to Arduino Due to VGA Monitor

#1

All, In case anyone is interested, I discovered online that an Arduino Due can easily be connected to a vga monitor. Where I am, monitors are being tossed away all the time, so I got my hands on a couple of small ones for testing etc, ordered a Arduino Due of ebay, (the best place for the Due, because Arduino does not make it any more.) connect it up, install the library for it, and display what ever data you want.
Can do monochrome (less wiring required for this), 8 bit color, resolutions will vary depending on either, and the instructions to right to it are very straight with print() and println() etc..
They even have instructions to connect to NTSC/PAL if preferred.

The website with all the details can be found at
https://stimmer.github.io/DueVGA/

#2

What were your plans for it? Use it a insta-visual device or maybe just like a visual reference for playing?

#3

to begin with, get it to show the name of the patch, whether a toggle or momentary button is on or off, the current position value of a rotary encoder, switching led's on or off. 16 leds, 8 momentary foot switches that will double up to make 16, and 8 rotary encoders that will also double up.
To keep it simple to start with, I just plan on coding all the references into the Due, so for a thought, if I choose patch number eleven, it will send the serial data from the axo to the due as number 11, and display the name connected to value 11. Its probably going to be a little different then that but I guess you get the idea. I am thinking of value sets to help display the values. example.. 101 will turn led 1 on, 102 will turn led 1 off etc.. encoders might be 1001 to 1128 for encoder 1 etc.. then I just display the value or, maybe a progress bar or something.. I will do most of the working out while building it. I expect it won't be too hard, just time consuming to get right.
It will probably take 2 weeks to arrive which should give me some time to catch up on some overdue soldering of the footswitches.

#4

I believe it would also be possible to drive monochrome VGA using Axoloti's GPIO. VGA needs VSYNC, HSYNC pulses and pixel stream. The sync pulses could be generated with the processor's PWM peripherals along with a pixel clock. The processor's SPI peripheral could be used to scan out the pixel stream from memory in slave mode using circular DMA. The actual processor load (for outputting VGA, but excluding drawing on the framebuffer) would be nothing but some general performance penalty caused by the memory bus occupation, for 640x480@60Hz monochrome the required bitrate is 25.175 mbit/s, SPI1 goes up to 45mbit/s.
If you 'd want to implement this you need to study the RM0090 pdf from stmicro, and some sort of logic analyzer or oscilloscope. I can advice if you have specific questions, but can't really offer to implement it myself, too many things on my development table already.

#5

Thanks @Johannes, I know there is already work done to go from the stm32f103 to vga, so I don't doubt the Axo can do it. Maybe to go on the list of idea's for archive, I could imagine someone purchasing an Axo in the future, and being able to plug in a monitor to it, even when connected to the gui, you build the patch on a computer etc.. and the Axo outputs relevant data to a monitor. Objects could be designed to select if you want the data displayed etc.. or even different kinds of triggers.. maybe even take some of the processing demand for displaying the data on the gui, like the spectrum analyser, oscilloscopes etc..
It would be great to contribute something, bu this out of my league for now.

I will stick to the Due for now, its more at my level for getting the outcome I desire, plus the additional GPIO's etc..I've decided to drop the Midi side all together, with 16 x momentary foot switches connected to 1 axo analogue, 8 x rotary encoders connected to 16 digital in on axo, so I need 16 digital outs for the led's connected to the momentary's which I will do through the Due. I will use the TX on the Axo to send data from the switches and momentary's to the Due and then play around with displaying it all on a vga monitor. I plan on mounting all this into a aluminium case, the monitor will be in the lid, all the rest goes into the case, but the footswitch panel will be separate from this, because its too big. So there should be plenty of space in the case for extra cables and effects pedals etc..I know all this is a bit off topic, but this is where I am at, just wanted to share the Due to VGA find. I think its cool because it will allow a large volume of info to be displayed, when other display devices are quite small and or costly. For me, the only cost is the Due $20.