I am currently communicating between two microcontrollers using a single pin and the LIN protocol over a short distance of 0.2m. Now I would like to extend the distance up to 5m by differentially driving the communication (using a RS485 or 232 transceiver etc.). It is not possible to change any aspect of the current design so I am thinking of attaching a PCB to the microcontrollers at each end and communicate between the PCBs differentially. Is anything like the attached image possible? The difficulty I am having is in splitting the signal from single to differential as most transceivers require an Rx and Tx. This would be fine If I could split the signal before the transceiver.
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1\$\begingroup\$ LIN is a common bus system in modern cars. The bus lenght can easily reach 5m without any problems. Do you have a LIN transceiver between your uC and LIN bus? It will handle the transmission voltage levels and ensure a clean communication. \$\endgroup\$– A.R.C.Commented Dec 5, 2018 at 10:42
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\$\begingroup\$ @A.R.C. the "using a single pin" part seems to answer your question. \$\endgroup\$– MapleCommented Sep 3, 2021 at 19:11
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2 Answers
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LIN is very slow protocol (20,000 bits per second) with controlled slew.
Just run a twisted pair (signal, return) between the two transceivers.
answered Nov 14, 2018 at 16:20
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\$\begingroup\$ The difficulty comes from converting from single line to a double line and then back again. I'd effectively like to go from LIN to RS485 and back to LIN. Any suggestions on how that could be achieved? \$\endgroup\$– ChrisD91Commented Nov 15, 2018 at 7:34
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\$\begingroup\$ LIN is very slow, and tolerant of large capacitances. Why must you use RS485? \$\endgroup\$ Commented Nov 16, 2018 at 3:10
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1\$\begingroup\$ @analogsystemsrf I find your answer as confusing as OP probably does. If you mean "ground" when you say "return" then why don't you say so? This would avoid questions about "double line". Also when transceivers came into picture? The OP seem to be using built in MCU hardware and wants to continue doing so. If you are suggesting some kind of signal boosting the you should provide an example, because as OP already pointed out LIN transceivers typically require separate Rx and Tx connections \$\endgroup\$– MapleCommented Sep 3, 2021 at 18:52
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LIN Spec 2.2A, Table 6.11 specifies the maximum length of the bus line as 40 meters. Converting to a differential signal for 5 meters won't achieve any extra reliability.
