TJA1043 - Normal Mode - Using for only Bus Diagnostic

[samfisher]

Hello all,

I want to detect if there is a problem in CAN Bus. At first, I thought that I can do it in listen only mode. As I understand from datasheet, bus diagnostic functions are only active when in normal mode. If so, what should I do to TXD pin? Should I connect it to ground or something else? Can I use TJA 1043 to only detect bus failures? I will not use a microcontroller. I want to show if there is an error with led with using ERRN pin. 

Thank you in advance.

[TomasVaverka]

Hello Sam,

You are correct that the TJA1043’s bus failure diagnostic is only active in Normal mode (STB_N = EN = 1). The ERRN pin will be pulled low when a bus error is detected. Keep in mind the current rating of the ERR_N pin as shown in table 8 of the datasheet. For more information, please refer to the AH1014, chapter 6.6 - Bus failure diagnosis.

BRs, Tomas

[samfisher]

Thank you for the reply, Thomas,

I will keep in mind about current rating. What about the TXD pin? Should it be connected to GND or 5V or something else to not to interfere the bus?

Sam

[TomasVaverka · Accepted solution]

Hello Sam,

I think the TXD pin can be left unconnected as it is internally pulled up to VIO.

BRs, Tomas