28 lines by 60 columns on a NEW Ativa 7-inch photo frame

[localroger]

As I recently suggested might be possible, I have written a working driver for the Ativa PF-7AW-201-P3R 7-inch digital photo frame which is currently available from Office Depot for around $39:

http://forums.parallax.com/showthrea...010#post981010

I will post a detailed writeup to my blog here later but for now enjoy the pix, peruse the code, and learn and some stuff I learned about these LCD's:

1. While the signals are very similar, the timing and everything else was completely different from the Philips PET 702 DVD player I recently hacked.

2. The signals give *no time at all* between the horizontal sync pulse and the first character to set up the video driver, so there is a 1-character wide border on the left side of the screen.

3. This driver emits a nonstandard frequency and number of lines, although it's in the NTSC ballpark. It doesn't give the double-line zero volt indication of vsync as the PET 702 did, but with some profiling I found a more subtle VCOM artifact that indicated vsync.

4. The video drive voltage needs to be higher; 3v3 overdrives it but 0v7 is way too low. In the picture I'm driving it at 3v3 / 2 and it could probably be a little brighter.

5. This frame has a slightly higher dot rate, about 10.3 MHz instead of 9 MHz, and my cool plan to have individual character colors within a line probably won't work without overclocking the propeller. Or you could reduce the horizontal character resolution to about 50, which opens up the timing.

6. It's 28 lines instead of 29 because the vcom artifact occurs several lines after the top of the screen. I couldn't figure out a way around this, as everything I tried destroyed sync.

The final display...



Before pix of circuit board...



...and after pix:



...and the driver: ativa_demo - Archive [Date 2011.03.06 Time 16.24].zip

[Dr_Acula]

Wow, this is amazing. Cost per character is very good = 39/(28*60) = 2c per character. Compare with a 20x4 LCD which is $15/(20x4) = 19c per character.

7" is the same size as my Android pad. I'm envisioning a 'Propeller Pad'...

[localroger]

I hadn't thought of it that way, Dr_A, but that would even make it worthwhile to offer modded units for people who want to experiment with them but aren't so proficient with the soldering iron. Even if the labor intensive mod doubles the price it still compares favorably with other displays.

[Rayman]

Very cool! Nice work.

BTW: Were you able to find any kind of datasheet for the display?

[localroger]

Rayman: BTW: Were you able to find any kind of datasheet for the display?

None whatsoever, although googling for any of the signal names reveals a lot of datasheets for similar products. In this case it was the labeled test points, visible in the pix of the bottom of the PC board, which got me in; I knew enough about how these things work from the PET 702 project (for which I did have a service manual) that I was able to work out the timing by experimentation. I was surprised at how different the timing turned out to be. I will be writing it up in detail by the end of the week (Tuesday is Mardi Gras, so not much gets done in New Orleans for the next couple of days LOL).

[doggiedoc]

@localroger - great work! You inspired me to pick up a DPF at Walmart (for the purpose of hacking). The didn't have the Aptiva but I thought I might get lucky.

Unfortunately - the Phillips brand isn't as hackable.

I plan to get the Aptiva you mention to give it a go. Keep up the inspiring work!!

Paul

[localroger]

Yeah, if the Philips DVD player I am hacking is any indication, they don't label anything; fortunately I was able to snag a service manual for it so I could find the signals. And while there is some similarity in the general scheme, it looks like there is no standardization at all of things like clock signals, amplitudes, dot rates, and such, so we'll have to be careful about exact model numbers when hacking these LCD displays.

[doggiedoc]

I plan to find an Office Depot tomorrow. See if I can grab on of the Ativa 7" you mention. I've email myself a copy of this thread so I can have the exact model handy on my phone when I get there.

Paul

[localroger]

doggiedoc, I wouldn't completely give up on the Philips frame you bought. If you have a scope once you see what the signals look like it gets pretty easy to recognize them; there's only a limited number of pins on the connectors to the LCD and the control chip. The alternating polarity video signals have a very distinct look; VCOM will be the signal alternating polarity each scan line, and not at normal logic voltages, and while the clock and sync pulses will probably be too short to see on a scope a prop using WAITPEQ to profile them should be able ID which is which in a jiffy. You do need to interrupt the video signals from the main chip and inject your own; again, just looking for them visually on the pins of the controller chip should allow you to cut the pins, and then you can inject at the ribbon connector if nothing else looks more promising. But all this is much more obvious when you've seen the signals in another device, and you do need a scope.

[doggiedoc]

I bought the Ativa from Office Depot today. Just got it apart, but don't have time to do anything else tonight. I have a PropScope - will see how they compare.

Thanks for the pointers!

Paul

[Oldbitcollector (Jeff)]

Ordered one of these tonight.. Looking forward to this hack. Maybe we can get it to do more than simple text.

OBC