Compatible cables (Cressi Leonardo)

[Daniel Samarin]

Hi all, new diver here. Potentially a dumb question:

I picked up a used Cressi Leonardo on ebay for cheap. Unfortunately for me, I didn't do my research on the availability of the data cable (infrared / maybe irda?). They are seemingly out of stock or discontinued everywhere. 

My question is whether the Leonardo, and obviously Subsurface, will be compatible with any old USB-to-infrared cable? Or, must it be IrDA specifically? I don't know much about the protocol, whether it's implemented transceiver-side or OS-side.

I took a quick look through some of the source code for clues, mainly serial_ftdi.c and user-manual.txt but didn't see anything leading me directly to an answer.

Thoughts? Should give up on this watch and buy another with available cables or bluetooth?

Thanks in advance,

Daniel

[Chris Kuethe]

I've got a half-hearted reverse engineering project that I'm slowly working on to make a compatible interface.

I don't see anything on the board where any special sauce might be hidden; it appears to be a pretty straightforward USB-IrDA interface. USB -> FT232RL -> MCP2122 -> MAX3120. I suspect the main clock is the LTC6390, and the 74HC020 is probably being used as a buffer. A buttload of decoupling capacitors, I'd guess, to stabilize the circuit when driving the IR LED. Unfortunately the back side of the board is nearly a solid copper pour for a ground plane with a couple of data traces crossing under power traces. No doubt you can appreciate my reluctance to start scrubbing off solder mask and stabbing the board with probes...

If you can find a cheap IrDA cable it might be worth trying it.

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GDB has a 'break' feature; why doesn't it have 'fix' too?

[Daniel Samarin]

A whole electrical engineering project is what I was trying to avoid, though I am an electrical engineer so I suppose this is in my wheelhouse.

If "IrDA is IrDA" then shouldn't something like this technically work (would need a Serial -> USB cable as well), assuming the infrared coupling is good enough?

https://www.tindie.com/products/locus_eng_inc/e2191-serial-to-irda-transceiver/

If I go down the custom route it wouldn't be so bad as long as I'm not writing any firmware... Could release the design and sell kits/pcba's as well to try and break even.

Thanks,

Daniel

[emmdarakis]

I was using this usb to ir dongle with my Newton (same ir interface with Leonardo):

https://www.divemate.de/fusiondescription/

In fact I have it sitting in my drawer collecting dust for months now (since my Newton died).  

 I could send it to you for free (or maybe you cover the postage only - no idea how much it would be - I live in Greece).

Pm me your details if interested.

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[Daniel Samarin]

That would be awesome. Apparently DiveMate discontinued the product years ago -- can't find it anywhere! I'll send you a message.

Still feels like this leaves other people hostage to finding discontinued stuff. I had a look at the MCP2120 datasheet and it shouldn't be too hard to go USB -> FTDI -> MCP2120 to create something usable. I'll order some sample parts and give it a go. Who knows, maybe it'll be quick work.

--Daniel

[Chris Kuethe]

On Tue, Oct 10, 2023 at 1:41 PM emmdarakis <emmda...@gmail.com> wrote:

I was using this usb to ir dongle with my Newton (same ir interface with Leonardo):

https://www.divemate.de/fusiondescription/

In fact I have it sitting in my drawer collecting dust for months now (since my Newton died).  

 I could send it to you for free (or maybe you cover the postage only - no idea how much it would be - I live in Greece).

Pm me your details if interested.

That speaks well of it being a generic IrDA device. I see some cheap "meter reader" cables on amazon that look like they're meant for interfacing with with electrical or water meters - perhaps they might work.