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/diy/ - Do It Yourself

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>> No.1783793 [View]
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1783793

>>1783595
>interface
doing what, exactly? what sort of messages are you needing to pass to and fro?
you can sometimes strip down a standard protocol, skipping particular components or cases or even whole protocol layers, in order to leverage the parts/layers of interest
picrel at top is a degenerated model of a half-duplex wired-OR bus where only one node can speak sensibly at a time. if you can get your devices working and talking to each other on the bench using that bus model, you can use any suitable wired-OR physical layer such as CAN or LIN to scale up the distance as in picrel at middle
>CAN
good physical layer. instead of dealing with the CAN controller, which is a complex machine designed for high performance and reliability, use a U(S)ART. note that CAN transceivers do have built-in send timeouts (300µs dominant bit time) according to fail-safety requirements of their intended use case and bit rate, so you will have to use a U(S)ART bit rate that ensures stop bits will occur at least that often (30kbps or more), orrrr
>LIN
LIN transceivers have a much longer built-in send timeout (6ms), so you could use the normal LIN physical layer and termination/wiring scheme, and configure the U(S)ART for normal non-LIN mode, then pass bytes back and forth at a lower speed, such as 9600bps. you can ignore the LIN wake-up condition, addressing, and power management stuff, just send and receive your bytes
recommend you bring signal ground and power with you over the data cable, and isolate your remote receiver from remote ground (optos?), so you'll have less to worry about ground offsets blowing one or the other end
>RS-485
good and reliable, but the manual transmitter enable is undesirable complexity. if you have dual twisted pair cable, you could build two simplex links and use them together as a full-duplex link, otherwise use stripped-down LIN or CAN as above

>>1783764
>authenticity
worse than reddit
https://en.wikipedia.org/wiki/Ship_of_Theseus

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