Multi-drop serial
Mickster
Posts: 2,609
I need to do something like this...opinions or better solutions? Prolly need schottky diodes for 3.3v(?)
Comments
If they are Prop chips then you can just combine the rx and tx and have the one wire bus that is driven by the selected slave with the others floating their tx though.
Strictly a speak-when-spoken to arrangement. I have these devices, distributed on a full duplex 422/485 bus but I now want to have 3 or 4 on one small board and it seems silly to have a MAX491 for each device.
@"Peter Jakacki"
no kidding....as I was typing the OP, I was thinking "Peter's gonna suggest OW again"
Not all devices are Props and so I'm stuck with RX/TX.
I actually prefer this arrangement because, no matter what, the master can always talk. The slaves are running motors and should one get its knickers in a twist and tie-up the shared response line, the master can still broadcast a shutdown command.
Many thanks for the input
btw, I use to write all kinds of complicated protocols for RS485 but I have been quite happy with the simple ping-pong type protocol I have been using on P1 and mean to implement it on P2 which should be very easy. There is never any lockup and with a P2P virtual connection on a multidrop line both ends have equal access and are self pacing and establishes a virtual "full-duplex" connection.
Probably better described as a FD, multidrop, 4-wire network, based on 422/485 transceivers.
I really enjoy using this stuff