General > General Technical Chat

Mystery optical(?) connector

<< < (4/7) > >>

fredmoro:
Hi.

I tested the communication: The messages were just reflections or something ... So I read my own message back in a distorted way. (you probably need some other component in the circuit, like a capacitor or something)
In the meantime, I have found a successor to SFH 7221, which is still available: SFH 7250 https://media.osram.info/media/resource/hires/osram-dam-2496516/SFH%207250.pdf
I think I’ll buy some and continue experimenting with them. This will at least ensure IR compatibility with WPM II

grumpydoc:
I suppose I really ought to find more time for this project  :) It's almost 3 years since I started - sadly I have essentially zero time for hobby electronics these days.

As it happens I found a WPMII at a reasonable price on eBay which rekindled interest - rather different board based on a µPD78F1168


--- Quote from: fredmoro on November 09, 2020, 11:54:00 am ---Hi.

I tested the communication: The messages were just reflections or something ... So I read my own message back in a distorted way. (you probably need some other component in the circuit, like a capacitor or something)

--- End quote ---

Yeah, it sounds like there are reflections meaning your phototransistor is picking up output from your IR LED - but none of the other circuits (see below) include anything to suppress "local echoes" so, presumably, if you get the two SHF7221/7250's close enough together and well aligned it is not a problem.

Sadly several of the pages referenced a couple of years ago no longer exist - though the web archive has a partial record, including this page https://web.archive.org/web/20160619033006/http://openv.wikispaces.com/Adapter+Eigenbau. The last but one is probably pretty similar to the hardware previously discussed in this thread but the last one is also interesting - utilising a USB interface but the TTL-level RS232/SFH7221 interface side of things is very simple.

As a starting point I reverse engineered the schematic for the WPM controller I bought (I chose to do that board because the serial I/O is on fixed pins on the 80C32 microcontroller so it was easier to start at those pins).



The red dots are where there are odd vias that I have not been able to trace. They usually start out on a trace on the top of the board but don't connect on the bottom of the board (it is 4-layer) and the ground fill prevents me from seeing if there is a trace going somewhere on an inner layer but it's quite possible that they don't go anywhere - the circuit seems complete without adding anything.

The enable is one of the data outputs from a 74HC4094 serial->parallel shift register, I assume this is just driven by the controller, I haven't bothered tracing it further.

So, next step is to figure out what else I need to buy, apart from a £1 SFH7250, to make minimum order at Mouser :)

alyy:
Hey hey grumpydoc, any progress here?  :D
I am on the very similar project, trying to link WPMW to ESP32 -> wifi -> mqtt server -> remote management.

geggi1:
Assuming you the inteface is very similar what used on fluke scoopmeters.
You can google "fluke scopemeter optic interface diy"
You can use a USB to serial converter at TTL level and a few additional componets to build the interface.

grumpydoc:

--- Quote from: alyy on November 04, 2023, 10:29:58 pm ---Hey hey grumpydoc, any progress here?  :D
I am on the very similar project, trying to link WPMW to ESP32 -> wifi -> mqtt server -> remote management.

--- End quote ---
Sadly not - mostly because I decided against leaving a connected PC, plus router, Livebox etc running 24/7 when we were not in the house.

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod