>-----Original Message----- >From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] >Sent: 25 September 2006 14:38 >To: Microcontroller discussion list - Public. >Subject: Re: [EE] I need a circuit for a bidirectional opto >isolated TTLinterface > > >On 9/25/06, Michael Rigby-Jones > wrote: >> >> >> >-----Original Message----- >> >From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] >> >Sent: 25 September 2006 11:26 >> >To: 'PICLIST' >> >Subject: [EE] I need a circuit for a bidirectional opto >isolated TTL >> >interface >> > >> > >> >I was thinking of using HEX inverters and opto isolators that >> >basically are two unidirectional circuits back to back. >> > >> >Works in simulation but do not know how well it will work >in the real >> >world :-( >> > >> >I want to opto isolate the JTAG programmer interface from the real >> >world as I may otherwise and with Murphy's Law help blow up my >> >programmer :-( >> >> The first problem is likely to be speed related, common/cheap >> opto-isolators are v..e..r..y s..l..o..w. > > >6N137 it's a common/cheap one (about $0.6 here if you buy >one): >http://www.datasheetcatalog.com/datasheets_pdf/6/N/1/3/6N137.sh tml Still quite slow though. I guess the OP needs to specify what kind of clock speeds his programmer is capable of, but JTAG programmers can have clock speeds in the 10's of MHz range. The magnetic isolation devices from Analog Devices as pointed out in another post look interesting. Not cheap compared to opto's but not too expensive for a one-off interface and they are capable of very high speeds. Regards Mike ======================================================================= This e-mail is intended for the person it is addressed to only. The information contained in it may be confidential and/or protected by law. If you are not the intended recipient of this message, you must not make any use of this information, or copy or show it to any person. Please contact us immediately to tell us that you have received this e-mail, and return the original to us. Any use, forwarding, printing or copying of this message is strictly prohibited. No part of this message can be considered a request for goods or services. ======================================================================= -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist