DMG/Pocket video capture with Arduino or Teensy? (Page 12 of 16)

rvan wrote:

Reading the Freescale Reference Manual, it turns out that the Teensy's chip does have two SPI ports.  We may yet be in luck...

...are those pins available on the board though? and is there software library support for two SPI ports?

Another option which does have support for two SPI ports is the good old Maple Mini, and it looks like they can be found pretty cheaply on eBay...

Well, I was in the process of moving when this thread started and then I got a new job ... and more than a month later, I have my home office mostly set up. I can finally dedicate some time and effort into this project.

Now, what I am doing is going back to the basics. For the time being I am ignoring Hsync and Vsync and just focusing on clock and data. That means if I get a picture, it will be skewed, but at this point, all I care about is a picture! Any picture! Also worth mentioning, I am working with a 16MHz arduino pro mini so I have to focus on sketch streamlining. The reason I set aside my Teensy is because they are expensive and anyone wanting to build this into a GB will be put off by the Teensy's price and size. I also think that the CPP to machine code conversion for the Teensy's CPU is worse than that of the atmega168.

I have to go grocery shopping before I can sit down and modify friendofmegaman's PC-side code but I have a simple fast program for the arduino:
1. wait for clock interrupt
2. Serial.print(PORTB)
3. repeat

PORTB is just a byte with data0 and data1 at the farthest right bits. The PC is going to do the horizontal counting for me, at least until I get a legit picture. Once I get that picture, I will implement Vsync. Hsync may remain as a simple counter on the PC-side.

Future goal: implement composite video output without the help of a PC.

brb

Jazzmarazz wrote:

Thats pretty neat, but you utilize port manipulation?

Of course - jump to Chapter 9 on GPIOs:

http://www.st.com/st-web-ui/static/acti … 171190.pdf

or even program in assembly if you like:

http://www.st.com/st-web-ui/static/acti … 228163.pdf

Jazzmarazz wrote:

Also worth mentioning, I am working with a 16MHz arduino pro mini so I have to focus on sketch streamlining. The reason I set aside my Teensy is because they are expensive and anyone wanting to build this into a GB will be put off by the Teensy's price and size. I also think that the CPP to machine code conversion for the Teensy's CPU is worse than that of the atmega168.

I suspect you're right that Arduino code will be more efficient that Teensyduino code, but I have to agree with friendofmegaman that you're going to be very pushed for cycles, especially using an interrupt and doing a serial write straight away.

Jazzmarazz wrote:

Speaking of which, it mag be economical to test a serially clocked parallel-in, serial-out shift register and process all five pins on the PC.

Do you mean converting CLK, D0, D1, HS, and VS to serial data?  Do you plan to send this data to a microcontroller, or are you connecting the DMG to the PC through something else?

Jazzmarazz wrote:

I have to go grocery shopping before I can sit down and modify friendofmegaman's PC-side code...

You might want to use this version of the display code which I've modified to use Pygame instead of Pylab.  Pylab was extremely slow here...

#!/usr/bin/python
#author: friendofmegaman, rvan
#Display captured frame data on the PC.  Expects a 0x1E00 header and four
#pixels per byte.  Uses pygame, which is faster than pylab's scatter.

import pygame
from pygame.locals import *

upscale = 2

width = 160
height = 144

grey = []
grey.append((224,248,208))
grey.append((136,192,112))
grey.append((52, 104, 86))
grey.append((8, 24, 32))

fd = open('/path/to/screen.bin', 'rb')
data = fd.read()
fd.close()

frames = data.split('\x1E\x00')
print len(frames), 'frames'

class Pixel:
    x = 0;
    y = 0;
    def __call__(self, col):
        for upy in range(upscale):
            for upx in range(upscale):
                window.set_at(((self.x)*upscale+upx,
                               (self.y)*upscale+upy), grey[col])
    
        self.x +=1
        if self.x==160:
            self.x = 0
            self.y +=1

pixel = Pixel()
window = pygame.display.set_mode((width*upscale, height*upscale))

for frame in frames:
    # First and last frames can be smaller than that (because there's small
    # chance we start capture right at the beginning of the frame)
    if len(frame)!=5760:
        continue

    for y in range(144):
        for x in range(160):
            bit_offset = y*320+x*2
            array_offset = bit_offset/8
            byte_offset = bit_offset%8

            byte = ord(frame[array_offset])
            px = (byte>>byte_offset)&0b11
            pixel(px)

pygame.display.update()

quit = False
while not quit:
    event = pygame.event.wait()
    if event.type == pygame.QUIT or event.type == KEYDOWN and \
    event.key == K_ESCAPE:
        quit = True

The 74HC165 is a Parallel-In, Serial-Out shift register... however I think that it may not be connected directly to a USB cable. lol
Maybe an RS232 cable, but not directly USB... it was a wild idea any way. The thought was to have no microcontroller to reduce size and cost.