Disposable Digital Camera Interfacing

Interface & Building a USB Cable

[camera pic from pcworld.com article]
On the side of the camera is a sticker that says "To protect your pictures, this sticker should only be removed by a Big Print Central Sales Associate -- Camera does not connect to home computers." But you've already paid your $11 and you own the camera, so go ahead and ignore it.  Under it, you'll find a 10-pin connector labeled J3. Each pin is also labeled, but that's hard to see from the outside. Pin 1 is closest to the shutter release button, and pin 10 is closest to the battery door at the bottom. Four of these pins form a standard USB interface that will allow connection to your computer.

Dakota Camera Pinout

Pin
 Signal Name
 Description
1
goes to R57 (unpopulated), to U2.79. Use unknown.
2
 Ground
3
R18 (4.7K) - U2.30 (P31) & delete button. Also through R68 (unpopulated) to JP1.2
4
R2 (unpopulated) - pin 6 of SST program memory FLASH. This is address bit 17, which isn't used by the size FLASH memory installed.
5
R5 (1K) - U2.33 (P13). Use unknown.
6
 USB +5V power
 Connects to red wire.
7
 USB Ground
 Connects to black wire (you can also use pin 2 or 10).
8
 USB Data +
 Connects to green wire.
9
 USB Data -
 Connects to white wire.
10
 Ground


The connector used on the camera is designed to be low cost, so it's really just some pads on the main printed circuit board.  The easiest way to connect up a USB cable is to solder directly to the camera's PC board.  This works, but it's delicate and makes the camera awkward to use.  A tip on buying USB cables: don't buy cables from a place that also sells printers. The only reason they are there is for the upsell opportunity; you'll end up paying $20 to make up for their slim margins on the printers.  I got a cheap USB cable from cablesforless.com - $1.89 including shipping (although the free-shipping offer has now expired) - and at a geek supply store I got a 10' cable for $10.

The connector is the same type used on the older Palm Pilots (thanks to the people at slashdot for finding that, including jc panda and omnigeek), and the good news is that cables for these machines are also older and generally discounted.  I got a Belkin "Palm III, VIII Hotsync Cable" (F3X1051-03) on sale for $4.97 at Radio Shack.  Cables like these are also reportably available at some dollar stores. The connector is a bit too big to fit in the camera, but by peeling back the plastic backing and filing down the two posts that go through the PC board, and I had a workable connector (I may still need to shim it).

Belkin Palm III/VIII Cable Pinout

Camera
Pin
Camera function
 Palm Cable
wire color
 Palm DE-9
Pin Number
USB wire color
1
red
 5
 white (see text)
2

n/c
3

n/c
4

n/c
5
green
 7
6
 USB +5V power
 black
 2
 red
7
 USB Ground
 blue
 8
8
 USB Data +
 brown
 4
 green
9
 USB Data -
n/c
10
 Ground
 yellow
 6
 black

The cable doesn't have any internal connections (verified with a good meter, not visually; there may be a capacitor between shields, but that's ok), so we won't be shorting out anything unintentionally. If you notice, one of the pins we need - pin 9 - isn't connected. There's a trick I can use: if you also notice that the dakota doesn't use pin 1 and 4 (although this isn't guaranteed in the future; they could populate those resistors), so if I short pin 1 to pin 9 at the Belkin's connector, I can take the pin 9 signal out the red wire. I also used the pin 10 ground instead of the pin 7 ground so that it would be harder to accidently short out the USB port.

I didn't look at the little circuit board in the cable (I was careful to keep it intact as much as possible), so I don't know if it labels the pins differently than the Dakota.

(Note: I have not completed the palm-pilot-like cable, so I haven't verified this works. Right now, I've got the 4 usb wires soldered directly to the camera's PC board).

Reader Matt H. suggested: "After the cable has been tested, coat the soldered joints with hot glue to prevent the wires from breaking due to metal fatigue."  I haven't finished the cable, so I can't comment on that yet!

Reader Ken T. wrote in: "I wired it up like you had in the diagram and it said "PC" on the camera so I thought I was in luck. Tried querying the camera and no go :( I then took a closer look and was able to pop the black case off the Belkin cable. It just snaps together but takes a bit of prying with a knife. Once apart I noticed a cap on the shielding. Took that off and wired the RED Belkin wire to Pin 9 with a small piece of wire to make a jumper. You can leave the cap on, but by removing it makes more room for the jumper. I snapped the case back together and wah-lah! It works, no mods to the camera, and looks like it was made for the camera!"


Palm III Docking Cradle
Michael Tempsch used an old Palm III docking cradle. He left the original serial wires intact as well as the sync button, and temporarily snipped the capacitor off (I'm not sure what it connects to, so this may or may not be necessary). He noticed that the pins on the dock's circuit board are labled in reverse order, and connected ground (black) connected to E1, white (USB data) to E2, green (USB data) to E3, and red (+5V) to E5.

Dennis Lou built this and documented documented it here.

Hacked Centronics Connector
David found a webpage that shows you how to build your own palm-like connector from a Centronics-style (parallel) printer connector -- if you've got one of these hanging around, it could be even cheaper to build a cable.

Dennis Lou built one of these cables and his description has some good pointers.

Add a USB Connector to the Camera
Zach Poff added a standard USB type-B connector to his camera so that he can use a standard off-the-shelf cable. He writes:

I scrounged the USB connector from a busted inkjet printer after looking in vain for a cheap palmIII cable to do the standard usb mod. First I removed a little of the back half of the camera shell to clear the new jack. Then I epoxied it onto the corner of the PCB with a little paper insulator underneath to prevent shorting against the PCB pads. Then I cut a little notch under the battery box to pass 2 twisted pairs from an ethernet cable to connect the OEM pads to the new jack. I soldered it together and tested, then used a sharp exacto to cut the front of the camera shell to clear. (A dremel would probably be safer. This plastic is a bit much for a blade.)

   


Verification
I don't have batteries installed in my camera (it's in a lot of pieces), so until I actually build the cable instead of using a soldered connection, I can only describe what happens without batteries.

When connecting the camera, there is a delay of about a second and then you should hear two beeps. (I'm haven't heard only one beep, but that might signify something). The picture counter will display "PC" and the green LED should light. When transferring pictures, this LED will flash.

If you have wired the USB data wires backwards, windows will indicate a communications error - I'm not sure about Mac or Linux.


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