topic Re: FlexBus connected to SJA1000 CAN Controller in Kinetis Microcontrollers

FlexBus connected to SJA1000 CAN Controller

jschepler — Wed, 04 Feb 2015 19:58:49 GMT

Hello,

The application for my microcontroller is to interface to 3 seperate CAN buses. I am using the TWR-K64F Tower Kit. For one of the CAN buses I used the integrated FlexCAN built into the microprocessor. For the next two buses, I will need to communicate with a seperate CAN Controller. The CAN Controller that I would like to use is an SJA1000. There are two modes of operation for this controller, Intel or Motorola mode. I will be operating the controller in Motorola mode because the R/WR signal is on one pin from the FlexBus.

This controller communicates on a parallel bus with 8 data/address pins multiplexed. I would like to use the FlexBus to communicate with the controller.

However, the controller needs an E (Enable) signal that goes high just after the chip select asserts, and goes low just before the chip select goes back high.

I thought I would be able to use the Byte Enable signal from the microcontroller and just invert it for the Enable pin.

I connected my oscilloscope to the EBI_BE_32_24_B pin on the C side expansion port but it never changes state.

I can view the clock out signal and chip selects on the oscilloscopes and those are working properly, but the byte enable signal seems to not be working.

Am I connecting to the wrong pin? Below is how I setup for using the BE_32_24_B pin:

Re: FlexBus connected to SJA1000 CAN Controller

Hui_Ma — Fri, 06 Feb 2015 03:50:17 GMT

Hi,

I think your code should be correct.

I also do a test with TWR-K60D100M board, which is using the same Flexbus module with K64 product, it shows the correct byte enable signal.

I just using the Kinetis 100MHz V2 sample code (KINETIS512_V2_SC) and just add the PTC17 setting to FB_BE31_24 function with below code:

PORTC_PCR17 = PORT_PCR_MUX(5);

Below is my scope copy for FB_BE31_24 signal vs. FB_CS0:

Wish it helps.

Have a great day,
best regards,

Ma Hui

-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

Re: FlexBus connected to SJA1000 CAN Controller

jschepler — Fri, 06 Feb 2015 13:42:05 GMT

It looks like my code was correct. Thank you Ma Hui for your response. The reason I was not seeing anything on my scope was because the pin I was connected to on the secondary elevator isn't actually connected to the microcontroller. Instead, the only place where PTC17 is connected is to pin 18 of Jumper 6.