DMG/Pocket video capture with Arduino or Teensy? (Page 2 of 16)

My Teensy will arrive tomorrow and I can finally start experimenting. I ended up purchasing Teensy 3.1 because it's the most powerful one. We'll see how much I'll be able to do with it.

In the meanwhile I prepared this breakout port:

It basically provides LCD pins 3 to 19. I decided to take out all the pins required to drive the the front PCB display and get input from buttons (already tested and it works).

Last edited by friendofmegaman (Apr 16, 2014 4:09 am)

So, my first experiment was a failure.
The objective was to capture a screenshot of LCD. What I did:

1. Checked how FlashingLEDs guy processed bit data to build the screenshot (here)
2. Implemented it in the Teensy
3. Collected frame data via serial
4. Tried to visualize it

And here's the result:

and it was supposed to be Tetris

I receive consistent data on the PC - each frame has 144*160 pixels, which is a good sign. Now I need to analyze the results thoroughly and double check everthing. I definitely am missing something here.

My Teensy code (rather dirty since I was too eager to see the result, didn't have time to do it by the book):
http://pastebin.com/1GUhf2nR

On the PC  side I used pyserial to collect data:

import serial

port = '/dev/tty.usbmodem34521'
speed = 4000000
buflen = 100
ser = serial.Serial(port, speed)

fd = open('screen_data.bin', 'wb')

try:
    while True:
        data = ser.read(buflen)
        fd.write(data)
except KeyboardInterrupt as e:
    print 'Shutting down'
    fd.close()
    ser.close()

Then I parsed it and built a scatterplot using matplotlib: http://pastebin.com/AS4uesLh

Hopefully I'll find some time this week to play with it more, but currently I'm a bit loaded with my actual work. Anyways if you guys have ideas what is wrong with my code I'd appreciate if you shared. Cheers!

Ok, I had spare 10 minutes at work and started analyzing the problem.
First things first I downloaded the dataset provided by FlashingLEDs (here) and tested my algorithm ont it. I found a couple of minor errors, but for the most part it works fine.

So the problem is either I don't read correct data from the Teensy for some reason or my uC code has some error I haven't noticed yet. We'll see...

Last edited by friendofmegaman (Apr 18, 2014 12:04 am)

In the previous pictures actually CLOCK should be swapped with DATA1, but that doesn't change the point.

I double checked the way my bits are packed - it's fine. Now I tend to think that I push data to serial when the frame is not ready yet. I have no idea why is that...

You could try ignoring HSYNC and just start a new line manually every 160 pixels? I also wanted to suggest sending the data after the 144th line where it looks like there is a nice gap in the timing, rather than on VSYNC?

So when decrease the clock speed on Teensy I observe worse readings of HSYNC... It appears that clock speed is still not big enough...

Last edited by friendofmegaman (Apr 18, 2014 6:44 am)

Good work so far, friendofmegaman.

I've started writing some Teensy code which uses interrupts, and hope to have my DMG wired up tomorrow.  I'll also test your code on my setup once the hardware side is ready.