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Author Topic: NMEA 0183 and RS-422 receiving  (Read 1074 times)
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skyjumper
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« on: April 08, 2011, 10:13:18 pm »
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Hi All...

I need to recieve two to three channels of NMEA 0183 and send one channel. I looked around for a level converter chip like a MAX232 but for RS-422, but no luck. Is there an easy circuit or chip to use to convert RS-422 to TTL, ideally with electrical isolation?

Thank you.
 
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CrossRoads
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« Reply #1 on: April 08, 2011, 10:52:34 pm »
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You mean a part like the MAX485, or one of its quad versions?

http://www.maxim-ic.com/datasheet/index.mvp/id/1111

quad TX
http://datasheets.maxim-ic.com/en/ds/MAX3030E-MAX3033E.pdf

quad RX
http://datasheets.maxim-ic.com/en/ds/MAX3093E-MAX3094E.pdf
« Last Edit: April 08, 2011, 10:57:32 pm by CrossRoads » Logged
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skyjumper
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« Reply #2 on: April 09, 2011, 01:05:20 am »
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Yes, very much like that Bob, thank you! I guess you now know what's coming ;-)
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CrossRoads
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« Reply #3 on: April 09, 2011, 11:01:57 am »
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Nah, just prescient!
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Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17

skyjumper
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« Reply #4 on: April 09, 2011, 12:43:34 pm »
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I also ran accross someone who had a line of chips with really good isolation built in. I'll have to find those and post. It was pretty early when I saw them and now I can't remember what company it was :-(
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Graynomad
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« Reply #5 on: April 09, 2011, 08:24:43 pm »
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To get isolation you have to use a chip with built in power supply isol. There are many for RS485, MAX3157 can handle a huge ground difference and they call it isolated but I haven't read the specs to see if that's really the case.

MAX1480/1490 are really isolated and ADUM2486/82/87 are as well I think.

Another way to do it is use simple 5v isolation chips (or optocouplers) and a small isol power supply. Look at ISO7240/1/2/3, ISO7220/1, IL15/16/17, ADUM1210.

______
Rob



 
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