TMS320F28032: Cannot get LIN TX or RX to work Keep blowing boards up.

William Dussault87

Part Number: TMS320F28032

I cannot find any decent literature on how to wire LIN TX or RX to get signals out. Can someone please help me I've blown two boards and cannot figure out why. Below is a diagram of the connection. I was thinking the loop back was blowing it up. The pins are not used in the GPIO and are currently configured as outputs They will be activated but I need to stop destroying things.

How do I correctly hook this thing up?

Thanks

over 7 years ago

0 Hareesh Janakiraman over 7 years ago

TI__Guru* 95315 points

William,

Not sure exactly what you are trying here. Attached is the LIN interface circuit that we use in our test-board, which appears to work fine.

0 Hareesh Janakiraman over 7 years ago in reply to Hareesh Janakiraman

TI__Guru* 95315 points

William,
I didn’t quite understand what you mean by “The pins are not used in the GPIO and are currently configured as outputs”. Please elaborate. Do you have a transceiver in your circuit?

Please take a look at the Application Diagram in page 19 of
www.ti.com/.../sn65hvda100-q1.pdf and let me know if it helps.

0 William Dussault87 over 7 years ago in reply to Hareesh Janakiraman

Intellectual 665 points

Currently both the pins were set to an "output" via GPIO registers. I created a loopback and then tried to set one to TX and one to RX and The TMS320F2803 Just dies. This Chip is behind an inverter which then requires some sort of isolation before I can hook it up to the LIN BUS analyzer we have. What is the part number of the IC you are using?

0 William Dussault87 over 7 years ago in reply to Hareesh Janakiraman

Intellectual 665 points

We do not have a transceiver in the circuit. I did not think we needed one but now I am guess that is a yes. I cannot understand how we fried a chip however. Was it because of the loopback? Can you possible explain that? Here is what were were using. We are going to change the GPIO but did not have the code yet written. I cannot find any decent literature besides the TMS320F2803x_LIN doc (rature Number: SPRUGE2B) But this does not explain the needed circuitry.

Thanks

Bill

0 William Dussault87 over 7 years ago in reply to Hareesh Janakiraman

Intellectual 665 points

The diagram makes more sense. I'll use an transceiver. Where do you think I should isolate this? After the Transceiver?

Thanks

0 Hareesh Janakiraman over 7 years ago in reply to William Dussault87

TI__Guru* 95315 points

William,

It would be hard for me to figure out why the chip got fried without access to the schematics and your test code.

Please check http://www.ti.com/interface/can-lin/products.html#p1389=LIN for TI's LIN portfolio.

Isolation is typically done at the MCU boundary.

0 Hareesh Janakiraman over 7 years ago in reply to Hareesh Janakiraman

TI__Guru* 95315 points

For questions related to transceivers, isolation etc, please visit our "Industrial Interface" engineering forum e2e at: e2e.ti.com/.../ .

0 Miguel Robertson over 7 years ago in reply to Hareesh Janakiraman

TI__Guru 62920 points

Hi William,

I'd recommend using a transceiver like TLIN1029 between your MCU and the LIN bus. This will serve to translate between the low-voltage logic interface the MCU uses and the high-voltage open-drain signals that are used for LIN. You can follow a similar connection to the one shown in Hareesh's diagram. If you need galvanic isolation for some reason (e.g., for safety concerns or to eliminate ground loops) then you could insert a digital isolator on the TXD/RXD interface between the transceiver and the MCU. (It will be much simpler to isolate these unidirectional logic-level signals than it would be to isolate the LIN bus directly.)

Regards,
Max

0 Hareesh Janakiraman over 7 years ago in reply to Miguel Robertson

TI__Guru* 95315 points

Please download the Application Report titled "LIN Protocol and Physical Layer Requirements" (SLLA383) from the TI website. That should answer your questions.

If you have no more outstanding issues, please close the post.

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TMS320F28032: Cannot get LIN TX or RX to work Keep blowing boards up.