• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 31 subscribers
  • Views 2696 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

SN65HVD233: SN65HVD233 CAN Transceiver problem..

oguzhan demirci
Intellectual 455 points
Part Number: SN65HVD233

"H All i,

We have a board with SN65HVD233 3.3V CAN transceivers. We monitor our CAN interfaces with PCAN-USB (CAN-to-USB) converter of Peak Systems.  

 

Link : http://www.peak-system.com/PCAN-USB.199.0.html?L=1http://www.peak-system.com/PCAN-USB.199.0.html?L=1

 

Let me define our problem. We had a Revision 1 board where we have no CAN bus problem. SN65HVD233 and PCAN-USB communicated without any problem at 250 Kbps.

Having made several capacitor-resistor additions on completely irrelevant section of the PCB, I have Revision 2 board manufactured. And now, i have the following problem :

 

1) SN65HVD233  cannot communicate with PCAN-USB  at 250 Kbps. Receive-RX (From PCAN-USB to SN65HVD233  ) works perfectly. Transmit-TX (From SN65HVD233 to PCAN-SUB ) doesn't work at 250 Kbps. Weirdly, while i cannot transmit data 00 to PCAN-USB, PCAN-USB somehow manages to capture some of the data AA

2) When, we reduced CAN bus speed to 10 Kbps, we managed to establish a somehow stable connection. Using this 10 Kbps, we tested other functions on the board. But this connection also crumbled all the time.

3)  Other functions on my Revision 2 board, ADC, DAC, Digital IOs and EEPROM all work as intented. So, there is not a general problem on PCB.

4) I connected CAN interfaces of Revision 1 and Revision 2 boards to each other. In this scheme, my Revision 2 board send a data at 250 Kbps, Revision 1 board reads it and transmit it back after incrementing data by one. This way i made sure that SN65HVD233 Chip or my CPU on Revision 2 board is working fine.

5) During the last few days, i monitored CAN outputs of Revision 2 board on Oscilloscope. What is see is that; Identifier, data and CRC are all correct. However, when i connect PCAN-USB to the board, PCAN-USB interrupts data at one point (changing everytime) and places an error frame. That's why i can't read data from PCAN-USB.

6)  Timings and signal quality is indistiguishable from Revision 1 board. However, i didn't care much attention to voltage levels as they seemed similar. I will now look into this aspect now. Before that, i wanted to consult to you :

 

- As i tried almost anything during the last few days, i now think problem could have something to do with 3.3V and 5V interoperability. Yes, my Revision 1 board works fine with PCAN-USB but i suspect that Revision 2 PCB manufacturing may broke down already fragile (and so far unknown) balance. One other reason that pushes me to think like this is that there is 3.3V-GND impedance difference between Revision 1 and Revision 2 boards.

 

- SN65HVD233 datasheet and SLLA337 (Overview of 3.3V CAN XCVRs) document states that 3.3V TI CAN transceivers are compatible with 5V CAN transceivers. But, the points i put above makes me suspect a 5V interoperability problem. ( Especially working connection between Revision 1 and Revision 2 boards). By the way, i used 3 different PCAN-USB cables, so i am sure that PCAN-USB cable is not the problem.

 

What are your opinions ? Do you think it may be due to different voltage systems ? Or do you have any other ideas that i am missing ?

 

Thanks in advance, any help is appreciated.

Ozi