TASCAM DR-40 remote control - data stream?

[easilyamused]

I'm trying to understand how the remote control on my TASCAM DR-40 PCM recorder works... I'm trying to make a remote start that is triggered by a uC rather than the wired connection provided by the RC-10 accessory. I bought the RC-10 to see how it works, and so far it's a bit of a mystery.

The RC-10 itself is an infrared transmitter, but the DR-40 only has a wired connection, so the transmitter unit slips into a plastic caddy that provides the wired connection out. I've opened up this caddy and as expected there's an infrared receiver with a bunch of passives, a couple of transistors, and one IC package. All of the components are SMD so the markings are proving tough to track down... The IC is marked "MFN0 1118 8GG"  (Images attached)

So, the wired connection contains 3 conductors on a TRS mini jack (2.5mm). Measuring the DR-40 unit (recorder itself) I found that sleeve is GND, but the other two conductors are both 3V3. I was expecting one of them to be a data line... So maybe the circuit in the remote caddy is doing more than just demodulating the IR signal?!

Does anyone have any tips as to where to start with this? Know what this "MFN0" IC is doing? I don't have a much test equipment - just a multimeter... though I did rig up an Arduino Uno as a basic DSO/logic analyzer

[SL4P]

I guess the first thing to identify is whether the wired connection is in fact a serial data stream, or a simple voltage ladder type of control.
You may be able to see something with a meter for the latter, but to be sure of anything, you really need to borrow a scope from somewhere.
Put all the pieces together for normal operation, then probe the data wire.
I'd expect open circuit or +Vcc when idle, then different voltages for each button combination... unless it is in fact a serial data control signal... which means you need a scope and some spare time.

[miguelvp]

Also you can check if the IR LED is actually transmitting by looking at it with a webcam or just your phone camera. At least this will tell you if it's actually transmitting anything to begin with.

Once you have that, maybe your Arduino DSO might be enough to see the signals, I doubt they are too fast but I have no idea how slow and Arduino DSO is.

[easilyamused]

OK great suggestions! I'll dig deeper and report back...

[easilyamused]

Ok so I found this http://jvde.net/node/7 for a different brand, different application.... But maybe a step in the right direction. I'll start breadboarding tonight!


Sent from my iPhone using Tapatalk

[SL4P]

That example is what I was suggesting for the voltage ladder idea - but controlled by the micro instead of switches... or of course it could be serial data.

Keep in mind (unlikely) that if it is a serial control, it may even be a bidirectional protocol that talks to other 'more advanced' remotes as well...

It may also be worth remembering that TASCAM (pro) and TEAC (consumer) are the same organisation - so you could find some parallel products if you look in there.

[ioannist]

The communication protocol is not public; however, somebody figured it out and posted it here

https://www.ghielectronics.com/community/codeshare/entry/1062

[w8aaaa]

Hey there,

First, props for this conversation, it's exactly what I was looking for, but ... 
Unfortunately the link to the communication protocol is no longer available.

Do you have any information? Is it a voltage leader or a serial bus?
I am tying to start and stopp a recording.

I hope you can help me.