MPC5775B + FRDMDUAL33664EVB compatibility for testing?

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MPC5775B + FRDMDUAL33664EVB compatibility for testing?

Contributor III

Are the MPC5775B EVB and FRDMDUAL33664EVB compatible for TPL board-to-board communication, for testing purposes?

We would like to send 48-bit messages (based on BCC examples) between the two boards.

We tried connecting the boards as shown:


But neither board receives messages from the other over the TPL interface.

I've verified with an oscilloscope that a 48-bit message is transmitted on TPL:


However, neither MPC5775B nor the FRDMDUAL33664EVB slave SPI blocks in the MBDT receive messages from TPL.  Each board receives echoes of it's own sent TPL messages (not what I would desire) but it suggests peer-to-peer communication over TPL between the boards should be possible.  What could we be missing?


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2 Replies

Contributor III

Below is what we see in FreeMASTER for a Simulink model that cycles through 3 different 48-bit output messages:


Could the fact that the transmitted TPL messages are immediately reflected back and received by the SPI Slave for both TPL1 and TPL2 indicate improper termination of the transmission line that connects the two boards?  Do the BCC boards have special termination not present in the FRDMDUAL33664 EVB or MPC5775B EVB?

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NXP Employee
NXP Employee

Hello @rsating 

I don't think I understand what you want to achieve. Do you want to communicate between MPC5775 with S32K over TPL?

The fact that you receive the frames sent from one target on the same target is normal. The SPI1 acts like, let's say a "MOSI" line while the SPI2 acts like a bit "MISO" line and TPL is a differential signaling. So if you put data on TPL from SPI1 you should be able to see it immediately on SPI2. The reason for which the SPI2 is used because the M will send a command to one of the S, connected to TPL. The S process the command, while meanwhile, the M will already stop the communication. So S needs now to reply to that command, so now, it will put data on the TPL line. But on SPI only M can initialize transfers so M will use the SPI2 as slave and will be triggered whenever on the S has sent a command over TPL. 

Hope this helps,



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