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FlexBus connected to SJA1000 CAN Controller

Question asked by jschepler on Feb 4, 2015
Latest reply on Feb 6, 2015 by jschepler

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:

 

 

 

 

 

flexbus_byte_enable.jpg

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