Well, they work! And I’ve got to say, they’re really fun.
But I’m onto the part where I’m ripping them apart, and praying that I don’t destroy them in the process!
In my research I found this thread over on Hack-A-Day’s forum where someone was hacking an iPod edition MyVu. He even got a hold of an engineer over at MyVu, and was able to get some information, which should be really helpful while I’m in process.
Based on what I found there, I started with cracking open the inline controller, which is where all the pin conversions happen, and things like brightness, contrast, and volume are controlled. Once I got it open, pulled out the screws, and peeled off the hotglue, I was pleased to see THIS:
All the wires were very nicely and clearly labelled.
Brown – GND
Orange – VIN
Light Green – IPOD_RX
Dark Green – IPOD_TX
White – VID
Blue – AUD_L
Grey – AVGND
Light Purple – AUD_R
Black – IPOD_DE
Red – REM_SENSE
No Shield – GND
I also popped off the casing around the Sansa 30 pin connector (mostly to verify everything…and figure out what REM_SENSE and IPOD_DE might be)
I’m really glad I did this, as there were a few surprises.
The pin/wire relationship here is:
4 – Red (D+) [REM_SENSE]
13 – White (?) [VID]
16 – Grey (?) [AV_GND]
17 – No Shield (?) [GND]
19 – Brown (?) [GND]
20 – Orange (?) [VIN]
27 – Blue (Audio Right +) [AUD_L]
28 – Purple (Audio Left +) [AUD_R]Note: Parenthesized text is documented pin responsibilities found here. while bracketed text is the wire relation listed above.
Also, while not shown in the picture, the Dark Green [IPOD_TX] and Black [IPOD_DE] wires were soldered together, while the Light Green was just hanging loose. I think that would make the IPOD_DE line something like a data clock, which is there connected to IPOD_TX (what I assume to be a serial receive line on the Myvu) to prevent it from going to sleep. I don’t know though, I’m just guessing.
The online Sansa pinout documentation is really lacking, but these connections give us some hints as to what they are.
16-19 is probably all ground pins. While 20 is likely a 3.3v line. (That seems to be what the expected supply voltage on the Myvu is. This is however not confirmed.)
Pin 14 is documented as a video pin, but it looks like 13 is as well. And it looks like either Myvu or the online documentation has the audio channels flipped on pin 27 & 28.
Finally, the mysterious REM_SENSE is starting to look like a clever way of saying “sleep sense” that monitors for device activity, or turns off the myvu in the absence of activity.
This is all pretty cleanly laid out though, which is nice. Should make the next step considerably easier.
