UART Multiplexing
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From: David Eather on 11 Apr 2010 18:55 On 12/04/2010 8:44 AM, eeboy wrote: >> >> 74HC4051 >> > > Sounds like the best solution so far... just don't like that I have to use > two (RX and TX) of these large (relative) components. > > --------------------------------------- > Posted through http://www.Electronics-Related.com there is also a 4052 and 4053 - you don't need two
From: D Yuniskis on 11 Apr 2010 20:10 eeboy wrote: >> If you're using 115K Baud will you be >> using all of the SECONDARY RS232 >> pins/lines as well? >> >> http://en.wikipedia.org/wiki/RS-232#Secondary_channel > > One thing I may not have been clear on. The communications from the UART > peripheral of the micro is simply logic level asynchronous serial > consisting of an RX and TX signal. No handshaking, no RS-232 voltage > levels. Then why are you even *looking* at analog switches/muxes?? They are *slower* than the logic gating that I have described and have capabilities you don't need!
From: Peter Bennett on 11 Apr 2010 20:28 On Sun, 11 Apr 2010 17:35:40 -0500, "eeboy" <jason(a)n_o_s_p_a_m.n_o_s_p_a_m.jasonorsborn.com> wrote: >One thing I may not have been clear on. The communications from the UART >peripheral of the micro is simply logic level asynchronous serial >consisting of an RX and TX signal. No handshaking, no RS-232 voltage >levels. Do the remote devices transmit whenever they wish, or only on request from your microcontroller? If they transmit on their own time, you will have great difficulty multiplexing them and extracting useful data, as you won't know which one to select when, or where in the message one is when you select it. -- Peter Bennett, VE7CEI peterbb4 (at) interchange.ubc.ca GPS and NMEA info: http://vancouver-webpages.com/peter Vancouver Power Squadron: http://vancouver.powersquadron.ca
From: Joe on 11 Apr 2010 20:36 On Mon, 12 Apr 2010 08:55:43 +1000, David Eather wrote: > On 12/04/2010 8:44 AM, eeboy wrote: >>> >>> 74HC4051 >>> >> Sounds like the best solution so far... just don't like that I have to >> use two (RX and TX) of these large (relative) components. .... > there is also a 4052 and 4053 - you don't need two You could also look at Analog's ADG787, a dual 2:1 Mux/Demux available in 10-lead LFCSP and MSOP packages and 10-ball WLCSP package, at sizes like 3x3mm, 3x5mm, and 1.5x2mm. One such device can multiplex 2 sets of logic-level Rx and Tx lines from your external devices to a set of Rx and Tx lines on your micro. But it's non stock at Digikey - <http://parts.digikey.com/1/parts/1100402-ic-mux-demux-dual-2x1-10lfcsp-adg787bcpz-500rl7.html>
From: eeboy on 11 Apr 2010 20:41
> >Do the remote devices transmit whenever they wish, or only on request >from your microcontroller? > Fortunately these two are only on request which is why I have chosen to multiplex these two. --------------------------------------- Posted through http://www.Electronics-Related.com |