pmod can period

[daeroro]

Hello, I'm working on zybo z7 & pmod can

I want to transmit data from zybo z7 to other board(not zybo, tms570lc43x launchpad).

 

So I took a test :

(computer) - (usb2can) --------------------------- (can transceiver) - (tms570 board).

 

It really worked well.

 

 

But I took a test like this:

(zybo-z7) - (pmod can) -------------------------------------- (can transceiver) - (tms570 board)

 

It doesn't work!!!!!

 

and the signal period is about 8 times slower than above picture..

How can I make it work?

I need your advice

 

thanks!!

 

[vicentiu]

Are you using Linux or bare metal on the Zybo Z7?

[daeroro]

10 hours ago, vicentiu said:

Are you using Linux or bare metal on the Zybo Z7?

Hi, vicentiu.

I'm using vivado + sdk

-hardware design : https://reference.digilentinc.com/learn/programmable-logic/tutorials/pmod-ips/start

-sdk example : https://github.com/Digilent/vivado-library/blob/master/ip/Pmods/PmodCAN_v1_0/drivers/PmodCAN_v1_0/examples/TX.c
 

 + I ran the Lookback.c  example and it worked!!

[vicentiu]

Ok. I'll move the thread in FPGA since this is the Linux area.

[jpeyron]

Hi @daeroro,

It looks like you have been able to alter the bit rate which was discussed in your other post here. 

I would suggest exposing the signals between the Pmod Can and the Zybo and using an oscilloscope on these signals.

Do you have a CAN bus analyzer so you can better see what is being communicated between the Pmod CAN and the tms570 board?

best regards,

Jon

[daeroro]

19 hours ago, jpeyron said:

Hi @daeroro,

It looks like you have been able to alter the bit rate which was discussed in your other post here. 

I would suggest exposing the signals between the Pmod Can and the Zybo and using an oscilloscope on these signals.

Do you have a CAN bus analyzer so you can better see what is being communicated between the Pmod CAN and the tms570 board?

best regards,

Jon

Hi, @jpeyron

Thanks for reply.

 

Unfortunately, I can't alter the bit rate.

The graph was changed even if I used same hardware design and SDK example. I don't know why.

 

Have you ever tried to change bit rate and it worked??

thanks!!

[daeroro]

Well, I figure out a bug in the example code.

In the CAN_Configure function :

   // Set CAN control mode to configuration
   CAN_ModifyReg(InstancePtr, CAN_CANCTRL_REG_ADDR, CAN_CAN_CANCTRL_MODE_MASK,
         CAN_ModeConfiguration );

 

needs to be changed like this:

 

   CAN_ModifyReg(InstancePtr, CAN_CANCTRL_REG_ADDR, CAN_CAN_CANCTRL_MODE_MASK,
         CAN_ModeConfiguration << CAN_CANCTRL_MODE_BIT);

 

So it can enter the configuration mode...

After changing the code, CAN communication between Zybo-z7 and MCU works really well.

 

You need to change your git example code.

 

[jpeyron]

Hi @daeroro,

Thank you for sharing a resolution to an issue with the Pmod CAN driver. We will pass this information on to our content team.

best regards,

Jon