[wizardgmb]

At this point, I'm trying to evaluate the WeatherDuino's transmitter and receiver boards to see if I can substitute a fiber optic driver and receiver for the RF devices (I avoid polluting the radio spectrum whenever possible). Given the schematics aren't available until after the purchase of boards, working from parts lists and photographs is slow going. So far, it appears the data lines from and to the respective Arduinos can be connected to logic level interfaced fiber devices.

Hi George and welcome.

I'd be very interested in how you go with interfacing to fibre optics. I take it we would need some TTL to fibre media converters.

BTW I think the old schematics are available, they should give you a good idea how it works (besides the ESP8266 stuff that's been added since).

Cheers UB

Actually the interfacing is pretty straight forward. I will be installing 850nm 62.5/125 cable because I have a enough to wrap around my house 100x and using type ST connectors (fiber version of the RF ST). The first number, 850nm, is the wavelength of light used and 62.5/125 refers to the size of the fiber core and outer reflective cladding respectively. This is the most readily available short distance cable and the ST connectors while out of favor today are  still easy to find inexpensively. Since I have the bulk cable, connectors and the required tooling, I will assemble my own cables but ready made cables can bought inexpensively on eBay.

Several decades ago, HP had an optical division and one of the products they developed was the HFBR series fiber optic transmitters and receivers. HP sold or spun the business off to Avayo and Broadcom eventually bought Avayo. The HFBR series are still being manufactured by Broadcom and thousands of them are for sale on eBay. Here is a HFBR device with its dust cap.



This is a typical link schematic:

https://drive.google.com/open?id=1-avEwP...49ly4n4Sxw

This circuit is TTL level in and out and capable of direct interfacing with a 5V Arduino, level shifters are required for 3V Arduinos. The base devices are usable from DC to 5 MBd, orders of magnitude more data rate than needed for a WeatherDuino interconnect. An HFBR pair is good for 1500 meters at 5 MBd and longer distances at lower data rates. If anyone is interested in the specific devices, the 5MBd transmitter with ST connectors is HFBR1412 and the companion receiver is HFBR2412.

If you take apart an older 850nm fiber device such as a 10BaseT to fiber converter from the 1980-90's, the odds are pretty good that you will find HFBR transmitters and receivers. I have a couple of those adapters I may scavenge for HFBR pairs.

Another alternative is to connect a MAXIM RS-232 driver to the transmit and use it to drive a commercial "off the shelf" RS-232 to fiber adapter. The down side of this approach is the need for another power supply for the adapter and the reverse channel goes unused. Yet another approach would be to use audio TOSLINK transmitters, receivers and manufactured cables. They are unidirectional but aren't as sturdy as the HFBR devices with ST connectors and 62.5/125 cable and the absolute maximum distance is 10 meters with 5 meters being the typical maximum.

Regards,
George

P.S. I'm sorry for the link rather than an actual schematic. I tried to embed the schematic image from my Google drive but the forum software couldn't handle the link.