LPC2000 CAN project

Sep 10, 2015 6 Replies
G

Greetings!



I have just join this group as it might be a good place to have some chat about NXP projects.



I want to make OBD2 scanner using one of the LPC chips. Now, I dont have any experience with CAN protocol, but I read about it and kind of understand how it works. What is not clear is if filtering of the messages is done by MCU or CAN controller ?



I found most of implementations is around MCP2515 CAN controller and MCP2551 transceiver.



I dont really know if theres a benefit of using LPC CAN controller over MCP2515, or just stick with any LPC and use the SPI for that? As MCP have



2 or 3 I/O buffers, is that enough for fast communication ?

What I want to achieve is to read some of the sensors from the car CAN and show it on a small TFT display.



Suggestions? Should I use LPC with CAN or stick with MCP ? Implications are that i need to make new PCB for LPC with CAN, and for MCP i can just order a board and connect it to SPI.


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R

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The LPC11C24 has a built-in CAN controller and CAN bus drivers. Embedded Artists had a demo board with this chip, may be others.

R.W.

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L

It may be worth getting a Komodo USB CAN interface and using that a bit to learn. They have a library that allows programming against the device, or you can just use their GUI for capture.

I have one connected to a Cubie board in this way. I'm sure a RasPi or Beaglebone Black would work as well, or you can just connect it to a Windows or Linux workstation/laptop/what have you.

Figure 4.2 on page 25 here:

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has some detail.

Les Cargill
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D

To echo what Roberto said: LPC11Cxx has an excellent CAN interface with built-in drivers (drivers in ROM) - quite easy to use. You'll want to get yourself a CAN book and study; CAN is quite different from other communication schemes.

IAR also makes an LPC11 starter/devel board which I used to get up to speed, before I designed a couple boards using LPC11C22. Provided free CodeRed studio (now owned by NXP) was quite good as well.

Hope that helps! Best Regards, Dave

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H

using a CAN module internally connected to the controllers peripheral bus is always a better solution compared with a CAN controller connected via SPI. Hundreds of controllers with integrated CAN are available by different manufacturers:

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You should take care to have a migration path to CAN-FD.

Heinz

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R

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Correct, but most do not have bus drivers. (Electrical buffers, not software.)

R.W.

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H

You are correct. The LPC11C22 and LPC11C24 parts include an on-chip, high- speed CAN transceiver. I assume it is a dual die implementation.

Heinz

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