Looking good to hack Ativa 7 inch photo frame
localroger
Posts: 3,451
Some of you might remember this thread where I proved out driver timing for the Philips PET 702 portable DVD player...
http://forums.parallax.com/showthread.php?129077-29-lines-of-60-characters-on-a-7-inch-portable-LCD
Of course the PET 702 is no longer in production, even though they're easy to get (and very cheap if you don't care about the DVD working LOL) from eBay. Still, I decided to throw $39 at something a little more current. Friends and Neighbors, I give you the Ativa model PF-7AW-201-P3R photo frame, currently available from Office Depot:
http://www.officedepot.com/a/products/101538/Ativa-7-Digital-Photo-Frame-Black/
I had a suspicion the signaling might be similar to the DVD player but it was a bit of a Smile shoot. After prying off the snap-on front bezel and unscrewing the bezel that restrains the LCD, the LCD turns out to have a single ribbon cable and a two-wire plug for the backlight. That flat cable is a problem. The DVD player was nice in that the LCD interfaced with wires, but the photo frame doesn't have to endure flexing as you open and close it. We have to find and interrupt the player's video to insert our own data, and I came up completely dry in a search for schematics.
But what's this? Scattered across the circuit board are a smorgasbord of, wait for it, labeled test points! Woohoo! Anyone want to take a guess what T_VR, T_VG, and T_VB might be? Yep, the scope meter confirms it; the exact same signaling as the DVD player used. And is this T_VCOM? Why yes, and while the voltage is much higher (10K resistor time) it's very obviously the same signal I used to slave the DVD display.
And just in case I need it there's T_3V3 and T_1V2. And an IR receiver on very long legs so the signal can easily be lifted to hijack it.
But what about disconnecting the video? Can't really mess with that little ribbon connector. Nope. But not far from T_Vx are three electrolytic capacitors, which are thru-hole components, and the ohmmeter reveals that one side is connected to each of the test points. A little more poking around reveals that these are actually the DC blocking caps for the three video signals; the video actually goes through them on the way from the CPU to the LCD! So I could simply pop them and hook my video feed into the end that faces the test point and LCD.
OR, a little more poking reveals that the three caps get their signal from three pins at one corner of the SMT controller chip. So this means I could carefully insert a jeweler's screwdriver under the three end pins and lift them while tapping with a soldering iron.
And being a photo frame it's intended to run continuously, so there are no worries about it going to sleep and not giving me sync any more.
AND there's plenty of room in the enclosure for one of the SMT prop solutions such as a nanoized protoboard, or for a couple of batteries and a Bodhilabs V-Pack to provide the 5V which the frame wants. And for that matter with the snap-on bezel removed the whole thing is small enough to mount in a larger enclosure which could still be pretty small and portable.
In any case it will be a few days before I am likely to get around to doing more work on this due to a little flurry of other activity I have to deal with, but I will get pix and more info up ASAP. Meanwhile, what I find exciting about this is that it suggests this type of signaling may be fairly universal in 7 inch LCD's at least, and that could mean a really huge trove of potentially hackable stuff is out there.
I wanted to go ahead and get this out because I suspect at least a couple of the usual suspects will find this encouraging enough to want to make a visit to Office Depot and do some investigating themselves.
http://forums.parallax.com/showthread.php?129077-29-lines-of-60-characters-on-a-7-inch-portable-LCD
Of course the PET 702 is no longer in production, even though they're easy to get (and very cheap if you don't care about the DVD working LOL) from eBay. Still, I decided to throw $39 at something a little more current. Friends and Neighbors, I give you the Ativa model PF-7AW-201-P3R photo frame, currently available from Office Depot:
http://www.officedepot.com/a/products/101538/Ativa-7-Digital-Photo-Frame-Black/
I had a suspicion the signaling might be similar to the DVD player but it was a bit of a Smile shoot. After prying off the snap-on front bezel and unscrewing the bezel that restrains the LCD, the LCD turns out to have a single ribbon cable and a two-wire plug for the backlight. That flat cable is a problem. The DVD player was nice in that the LCD interfaced with wires, but the photo frame doesn't have to endure flexing as you open and close it. We have to find and interrupt the player's video to insert our own data, and I came up completely dry in a search for schematics.
But what's this? Scattered across the circuit board are a smorgasbord of, wait for it, labeled test points! Woohoo! Anyone want to take a guess what T_VR, T_VG, and T_VB might be? Yep, the scope meter confirms it; the exact same signaling as the DVD player used. And is this T_VCOM? Why yes, and while the voltage is much higher (10K resistor time) it's very obviously the same signal I used to slave the DVD display.
And just in case I need it there's T_3V3 and T_1V2. And an IR receiver on very long legs so the signal can easily be lifted to hijack it.
But what about disconnecting the video? Can't really mess with that little ribbon connector. Nope. But not far from T_Vx are three electrolytic capacitors, which are thru-hole components, and the ohmmeter reveals that one side is connected to each of the test points. A little more poking around reveals that these are actually the DC blocking caps for the three video signals; the video actually goes through them on the way from the CPU to the LCD! So I could simply pop them and hook my video feed into the end that faces the test point and LCD.
OR, a little more poking reveals that the three caps get their signal from three pins at one corner of the SMT controller chip. So this means I could carefully insert a jeweler's screwdriver under the three end pins and lift them while tapping with a soldering iron.
And being a photo frame it's intended to run continuously, so there are no worries about it going to sleep and not giving me sync any more.
AND there's plenty of room in the enclosure for one of the SMT prop solutions such as a nanoized protoboard, or for a couple of batteries and a Bodhilabs V-Pack to provide the 5V which the frame wants. And for that matter with the snap-on bezel removed the whole thing is small enough to mount in a larger enclosure which could still be pretty small and portable.
In any case it will be a few days before I am likely to get around to doing more work on this due to a little flurry of other activity I have to deal with, but I will get pix and more info up ASAP. Meanwhile, what I find exciting about this is that it suggests this type of signaling may be fairly universal in 7 inch LCD's at least, and that could mean a really huge trove of potentially hackable stuff is out there.
I wanted to go ahead and get this out because I suspect at least a couple of the usual suspects will find this encouraging enough to want to make a visit to Office Depot and do some investigating themselves.
Comments
What about putting a DB15 connector at the back and using it like a VGA monitor? Would that work?
I think this is a semi-standard for 7 inch displays in particular. Displays with higher vertical resolution would not be vertically pixel addressible. The impression I am getting is that this is specific to 480 x 234 pixel displays. The smaller display OBC & co. hacked awhile back used regular NTSC; others are known to be pure digital. I think higher resolution displays are more likely to be pure digital in order to get pixel addressability.
I'll have more info on this particular unit in a couple of days. Right now the epoxy is curing :-)
A 7" display is pretty much perfect for Propeller experimenting. I'm looking forward to seeing more on this..
OBC
Maybe you could reverse feed 5V too, so that the display powers your Prop board...
It comes apart very easily and seems to have the same strange RGB interface as this one.
I did find the datasheet for the LCD, but I still don't really understand the signals...
I hacked a Viewsonic frame recently and am able to connect the buttons to Arduino allowing me to trigger slide advance with other sensor input. However - I need to rewire the PCB, and have DC connectors to do it. It seems that it's getting power (the orig was 3.3v), but it won't turn on. Also - the original DC connector that was soldered on had snapped off - but had three solder points. I'm not sure what the 3rd would be, or if I might need to utilize it?
Anyone have any experience or advice? I want to be able to rewire these things to give me ability to have distance between the frame and the power adapter.
Thanks in advance!
Claudia
Second, that third pin probably isn't used.