On 03.05.17 22:40, Gene Heskett wrote: > On Wednesday 03 May 2017 22:29:43 Chris Albertson wrote: > > RS422 is balanced and opt isolated at the Mesa card end so you likely > > have better noise resistance then with SPI. > > rs485 is the single ended cousin. Could a atom board keep up with that > with a pci-e rs422 card in it? That does have a bit of an attraction, > particularly from the noise safety dept. Silly Q: can the pi do rs422 > over its gpio?
Hook a RS485/RS422 transceiver to a Pi's serial TXD & RXD, and terminate each end of the twisted pair cable in 120 ohms, then it's done. All the chip does is TTL/CMOS to differential Tx & Rx. I bought some surplus DS3695A RS485/RS422 half-duplex transceivers a few days ago for US30c each, but they draw over 27 mA, idling, - a MAX485 gets by on 300 uA, though it'll only do 2.5 Mb/s. The SN65HVD485 will do 10 Mb/s on long lines, and draw 1 to 2 mA. (They may be the one Jon likes?) Just watch pinout, driver enable logic, and whether it's full/half duplex. The former has separate Tx & Rx cables (4 wires) vs 2 wires. Incidentally, it's the RS485 which is multipoint - just in case you want that, and go to put plastic down. Erik ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
