LIN communication with just SCI

[dianesterhuyse]

I have a design that still uses the MCF51JM128 Coldfire MCU and I need to add LIN communication capability for an automotive application.  In the JM128 documentation I see that the SCI supports LIN.  Does anyone have the LIN stack for use with this processor or will I need to use something like an ST L9637 to handle the communication?  Space on the board is VERY limited, so not having to add another SOIC component would be a huge bonus.  For what it's worth, I'm using CodeWarrior 5.9.0.

[TomE · Accepted solution]

The original poster had two questions, but confused them.

1 - "Does anyone have the LIN stack..."

They're asking if NXP provides a LIN App Note with sample code to run the SCI so they can get it working quickly. Forcing engineers to write code directly from the register definitions in the User Manual is so 1980's.

I would suggest searching NXP's site for "LIN Application Notes" and see if any app notes and sample code has been written for OTHER CPUs (including the ARM, MPC and Kitetis ones). The "TRK-KEA8 StarterTRAK" might come with sample code.

2 - "will I need to use something like an ST L9637 to handle the communication?"

Secondly, like most other off-board hardware interfaces (Ethernet, CAN, RS-232, RS-432, USB) an external transceiver is needed to convert the delicate 3.3V signals from the CPU into the ones required externally. In the case of LIN, 0-12V with lots of protection against nasty levels and spikes. We use the ATA6663, but the L9637 would work the same. NXP even has LIN Transceivers like those shown here:

https://www.nxp.com/products/interfaces/automotive-lin-solutions:MC_53488

The above pages should reference kits where you might be able to find sample code.

Maybe NXP Tech Support could provide links to other pages like this?

Tom

[TomE]

The ST LIN Transceiver Data Sheet has an example schematic that shows how the transceiver connects to a micro. Microchip have LIN App Notes for their CPUs that you might be able to get some clues from.:
https://www.microchip.com/en-us/application-notes/an891
You might even try asking ChatGPT to write some code for you.

Tom

[dianesterhuyse]

Tom, 

Thank you so much for taking the time for such a detailed answer.  I've been looking at NXP and I like the TJA1022 as it has two LIN transceivers which will work great for what I'm trying to accomplish!  Appreciate the advice!

[Bio_TICFSL]

Hello,

What you mean by protocol? The LIN on the MCF51 are, two SCIs with full-duplex, non-return-to-zero (NRZ) format
— LIN master extended break generation
— LIN slave extended break detection
— Programmable 8-bit or 9-bit character length
— Wake up on active edge

Regards