topic TJA1043 - Normal Mode - Using for only Bus Diagnostic in Other NXP Products

TJA1043 - Normal Mode - Using for only Bus Diagnostic

samfisher — Thu, 05 Dec 2024 08:10:37 GMT

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.

Re: TJA1043 - Normal Mode - Using for only Bus Diagnostic

TomasVaverka — Thu, 05 Dec 2024 10:11:46 GMT

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

Re: TJA1043 - Normal Mode - Using for only Bus Diagnostic

samfisher — Tue, 10 Dec 2024 05:30:40 GMT

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

Re: TJA1043 - Normal Mode - Using for only Bus Diagnostic

TomasVaverka — Tue, 10 Dec 2024 08:01:05 GMT

Hello Sam,

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

BRs, Tomas