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Groups > comp.arch.embedded > #31626
| From | pozz <pozzugno@gmail.com> |
|---|---|
| Newsgroups | comp.arch.embedded |
| Subject | Re: Half-duplex RS485: simple auto-direction solution |
| Date | 2023-03-06 10:41 +0100 |
| Organization | A noiseless patient Spider |
| Message-ID | <tu4cfl$1kma2$1@dont-email.me> (permalink) |
| References | <ttt6er$j2af$1@dont-email.me> <ttv8nj$v1jm$1@dont-email.me> |
Il 04/03/2023 12:06, David Brown ha scritto: > On 03/03/2023 17:15, pozz wrote: >> I think you already know this trick: connect DE/RE signals of RS485 >> half-duplex transceiver to TX *negated* signal from UART and connect >> TX input of transceiver to GND. >> >> If the bus is not driven by anyone, A signal goes high and B signal >> goes low thanks to the pull-up/down resistors. >> >> The trick uses the fact that the undriven bus and transmitting 1 is >> the same thing: A is high and B is low. So, when transmitting 1 the >> driver is disabled (DE=0), when transmitting 0 the driver is enabled >> (DE=1). Because TX is set to 0, A goes low and B goes high. >> > > This arrangement is also known as a "CAN bus driver". CAN is a well-known and very reliable network. Does this mean I could use RS485 in "CAN bus driver" arrangement without critical problems? >> Of course this works in ideal and good conditions. When should I worry >> of this trick? I suspect the edges of 0 to 1 transitions are slowed down. >> >> I don't use mega-baudrate, in this application I'm using 38400bps. >> >
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Half-duplex RS485: simple auto-direction solution pozz <pozzugno@gmail.com> - 2023-03-03 17:15 +0100
Re: Half-duplex RS485: simple auto-direction solution Richard Damon <Richard@Damon-Family.org> - 2023-03-03 11:26 -0500
Re: Half-duplex RS485: simple auto-direction solution David Brown <david.brown@hesbynett.no> - 2023-03-04 12:06 +0100
Re: Half-duplex RS485: simple auto-direction solution pozz <pozzugno@gmail.com> - 2023-03-06 10:41 +0100
Re: Half-duplex RS485: simple auto-direction solution David Brown <david.brown@hesbynett.no> - 2023-03-06 12:48 +0100
Re: Half-duplex RS485: simple auto-direction solution Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-06 11:23 -0800
Re: Half-duplex RS485: simple auto-direction solution pozz <pozzugno@gmail.com> - 2023-03-06 22:20 +0100
Re: Half-duplex RS485: simple auto-direction solution Rick C <gnuarm.deletethisbit@gmail.com> - 2023-03-06 16:47 -0800
Re: Half-duplex RS485: simple auto-direction solution Don Y <blockedofcourse@foo.invalid> - 2023-03-06 14:23 -0700
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