Problem sending data on CANBUS thorugh UJA113x System Basis Chip (SBC).

[abhi1992]

Hello Everyone,

I am facing an issue while using UJA113x System Basis Chip (SBC).

See Link: http://www.nxp.com/docs/en/data-sheet/UJA113X_SER.pdf.

I have programmed the NVM (0x71 to 0x74) to get out of Forced Normal Mode. by setting FNMC = 0 and SDMC = 1.

On-Startup I send the following SPI commands to device:

CMD 1:  (0x0207) - Write operation at MC(Mode Control) 0x01h register, to send the device into normal mode.

CMD 2:  (0x4002) - Write operation at CAN Control register 0x20h, to disable CAN transceiver shutdown(CSC bits) and select operating mode(CMC bits) to Active Mode(under voltage disabled).

I have made sure that data is available on TXDC pin . But still, I m not able to see data on CANBUS i.e. CANH and CANL (pin 21 and pin 22). I tried to see data on CANBUS through logic analyser but both both lines are at LOW level.

Are there any more registers which need to be configured ?

[dietmarschmid]

Hello,

which device are you programming?

Do you have proper supplies on Vbat, did you connect Vcan?

If you are after inital power up in Forced normal mode CAN Transceiver should be already working.

did you lock MTP after programming reg 70 to 74 with CRC value and did you see reset happen afterwards?

Take a look with the scope if you see your CAN H , CAN L pin moving

[abhi1992]

Hello Dietmar,

Thanks for your support.

Earlier the device was booting up to Forced Normal Mode and CAN communication was working perfectly. Later, I programmed the NVM(0x71 to 0x74) and 0x75(CRC) with correct value as the device powers up and goes to standby mode after performing a reset.

>which device are you programming?

Im Programming UJA1131F5V0 device.

>Do you have proper supplies on Vbat, did you connect Vcan?

Yes, Vbat is 12.3v,  Currently, On my Board VCAN is showing 0 v. I'm assuming that getting out of Forced Normal Mode has caused this transition to happen from 5v to 0v or I might have damaged the board while testing :smileysilly: due to which VCAN is showing 0v.

>If you are after inital power up in Forced normal mode CAN Transceiver should be already working.

No, As I reprogrammed the NVM. Currently FNMC = 0(Forced Normal Mode Disabled) & SDMC = 1(Software Development Mode Enabled). So, On power up It goes to standby mode and then I send command (0x0207) to send it into normal mode(I want to operate the chip in NORMAL Mode in future rather than Forced Normal Mode).

>did you lock MTP after programming reg 70 to 74 with CRC value and did you see reset happen afterwards?

Yes I placed the correct CRC Value in 0x75 register and reset occurred.

>Take a look with the scope if you see your CAN H , CAN L pin moving

CANH and CANL both are at 2.524 Volts.

I have a Question to ask:

- PIN NO. 20 on SBC (VCAN), does it generate a 5v o/p or should it be given a 5v i/p ???

Regards,

Abhishek

[abhi1992]

Hello Dietmar,

Sorry, I had one more doubt.

I have enabled the SDMC bit (SDMC = 1) in 0x74 register of NVM. i.e. Software development mode is enabled

In datasheet page no. 20 they(*manufacturers) have mentioned it as " Software Development mode (Software Development mode is provided
for test purposes and is not an SBC operating mode " can it be a possible reason for VCAN to be 0v?

Regards,

Abhishek

[dietmarschmid]

Hello Abishek,

Vcan is an input,  needs concection to a 5V  for example V1 or V2.  

did you leave it open?

[abhi1992]

Hello Dietmar,

Thanks for your support. It helped a lot.

On My board pin no. (2&3) i.e V2 and VEXT are shorted and are connected to VCAN. The output from V2 is connected to VCAN and I noticed that V2C bits(3& 2) were set to '00' in Regulator Control register (0x10h). So, I reprogrammed it '10' and now VCAN is getting 5v . CAN communication is working fine now.

Regards,

Abhishek

[abhi1992]

Hello Dietmar,

I'm facing a problem in restoring factory preset values. As mentioned in datasheet, pg no - 88  '7.13.2 Restoring factory preset values'. I applied the mentioned changes as follows:

1. Reset pin directly connected to GND.

2. CANH is pulled up to VBAT(12V in my case), with a 33K (1/4 W) resistor.

3. CANL is pulled down to GND, with a 33K (1/4 W) resistor.

After applying this configuration I switch ON the power supply for 5 secs and then turn it OFF. After this when I turn ON the supply it again enters into Stand-By Mode rather than Forced Normal Mode.

Please let me know if you have tried to restore factory preset values and what configuration you applied.

Regards,

Abhishek