TOSLINK as cheap fiber communication? - Page 1
Forum section: electronics / projects

author: technix
author_rank: Super Contributor
timestamp: July 29, 2015, 04:34:45 pm
content: Do you guys consider TOSLINK hardware a viable way of hobby-grade fiber telecommunication? I have tried it and it worked with reasonable enough effectiveness.I have even designed a simple 5-pin, nondirectional card edge connector as my "low speed optical module standard" that carries a UART up to 16MHz using a pair of fiber with TOSLINK connectors, in the same vein as SPF or SPF+ modules.

author: fcb
author_rank: Super Contributor
timestamp: July 29, 2015, 05:11:58 pm
content: Why? What are you trying to achieve??TOSLINK (which is POF - plastic optical fibre) will transmit a reasonable amount of data (10+Mbits) over a fairly short distance (a few M). If you want to go further then you'll have to move over to glass fibre, which is cheaper per M (although the tx/rx are more expensive than POF types, and you'll have to pay for terminations.I've used IFO parts from LasIRvis.co.uk before if you need an alternative to TOSLINK for POF.

author: linux-works
author_rank: Super Contributor
timestamp: July 29, 2015, 05:45:32 pm
content: its acceptable for hobby use. the connectors are cheap, the isolation is good, data rate is good enough and in the end, its still just ttl signaling on a serial interconnect.add 2 of them for bidirectional use (2 paths).

author: technix
author_rank: Super Contributor
timestamp: July 29, 2015, 06:08:23 pm
content: Quote from: fcb on July 29, 2015, 05:11:58 pmThe problem is that at least in China glass fiber and related equipment are too expensive for me. If situation calls for it I am going to inspect using glass-core multimode LC fiber for such low speed control (and using the same 5-pin electrical interface)

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 30, 2015, 01:43:31 am
content: The receivers are AC coupled and don't like long run lengths.

author: tszaboo
author_rank: Super Contributor
timestamp: July 30, 2015, 09:10:48 am
content: Quote from: NiHaoMike on July 30, 2015, 01:43:31 amNot according to this:http://media.digikey.com/pdf/Data%20Sheets/Toshiba%20PDFs/Fiber-Optic%20Devices%20TOSLINK.pdfI think it is the ACT (gain control) which makes it look like AC coupling.You can NRZI or manchester code the signal, if you have to transmit DC. Although, I'm still waiting for someone to release a MHZ class cheap SERDES ASIC.

author: technix
author_rank: Super Contributor
timestamp: July 30, 2015, 09:19:42 am
content: Quote from: NANDBlog on July 30, 2015, 09:10:48 amMy TOSLINK-based module transmits 9600-115200 baud UART directly perfectly fine. Maybe I can tru drive it faster even, up to a few Mbaud.Also I think 74AC class can work up to 100MHz, and my experiences with small MAX II CPLDs (like EPM240T100C5N) told me that those can be programmed into a 75MHz SerDes.

author: Marco
author_rank: Super Contributor
timestamp: July 30, 2015, 09:32:48 am
content: TOSLINK cables are POF, but really shitty POF. Avago says they can do fast ethernet over 70m NA0.3 POF with their transceiver.GI-POF can do a lot better than that of course, but I don't know if you can buy COTS transceivers for that. At that point alignment probably becomes just as big a headache as with glass fiber, but bits of fiber not having the ability to outright murder you is nice.

author: technix
author_rank: Super Contributor
timestamp: July 30, 2015, 01:06:08 pm
content: Quote from: Marco on July 30, 2015, 09:32:48 amMy TOSLINK POF transceiver modules costs me 3 bucks to make and I will sell them for 5 bucks each, and for two bucks I can get a pair of 10 meters long fiber that works with reasonable performance. Good enough, I think.

author: madires
author_rank: Super Contributor
timestamp: July 30, 2015, 01:39:47 pm
content: TOSLINK is fine for low speed applications, i.e. up to 25 Mbit/s or so. For higher data rates you should use multimode OM3 or OM4, which are standard for short range (roughly 500m) network (Ethernet) and optical transport (SDH) applications.