2385198_en-US

[#1]

UJA1169ATK/F/3

I'm using UJA1169ATK/F/3 connected to a S32K146 CPU on FlexCAN1. The UJA1169ATK/F/3 is used in Partial Networking with WakeUp Frame (no FD!) to wakeup the whole system from a deep sleep mode.

Actually every thing works correctly if a valid Frame is sent within the CAN BUS (for valid Frame a mean a frame which is compatible with the filtering masks selected).

The problem arise when an unwanted Frame (i.e. a frame, non FD, which is syntactically correct but do not pass the WUP filtering in use) is sent. What happen is that, quit often, if one such frame is sent, than any successive valid Frame does not wakeup the transceiver any more. It seems that, when an unwanted Frame, often, locks the capability of the UJA1169ATK/F/3 to correctly recognize valid Frames and hence to wakeup.

At first i suppose the problem could be something on the bus which generate a bus error which in turns switch the UJA1169ATK/F/3 in reset mode without moving RX signal and thus without advise CPU. But this is not the case, since i used a CAN monitor and no bus error are recorded (note that i use a Windows application to generate messages on CAN BUS and another application to monitor the bus; both application use separate USB/CAN converter).

Do you have any idea of which could be the problem ?

Re: UJA1169ATK/F/3

Hello Michele,

The behavior you describe is most likely related to the internal PN error handling of the UJA1169A.

The device maintains an internal frame detection error counter. If a sequence of frames is received that do not match the configured PN filters (or are interpreted as invalid in PN evaluation), this counter can overflow and trigger a PN frame detection error (PNFDE).

Once this condition occurs, the SBC may temporarily stop correctly recognizing valid wake-up frames, which could explain why subsequent valid frames no longer wake the device.

I recommend checking the PNFDE status bit and verifying the PN configuration (ID/mask, DLC, data mask and data rate settings). As a debug step, you can try disabling data field evaluation (PNDM = 0) to determine whether the issue is related to data filtering.

Please let me know the observed PNFDE state and PN configuration so I can further support your analysis.

BRs, Tomas