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Original question:

TCAN1145-Q1: PWRON flag set condition

TCAN1145-Q1: Behavior of SW_EN flag in fault condition

Punith Chandra
Prodigy 110 points
Part Number: TCAN1145-Q1

Tool/software:

Hi Team,

The user manual says that the selective wake enable flag SW_EN is disabled when a fault condition or FRAME_OVF occurs.




The transceiver is configured with all the selective wakeup parameters, set SW_CFG to 1 followed by SW_EN to 1, then put it into NORMAL mode and all the interrupt registers are cleared, there is no bus activity for tINACTIVE time, then the device is transitioning to SLEEP mode. As per the expectation, the device should wake up (switch to STANDBY) when the valid WUF is received. However, in our testing we found that the device is switching to STANDBY state when any CAN message is sent. Basically, selective wakeup is not enabled in this time. However, if we put the device to sleep mode and then the device is waking up only for valid WUF as per the configured conditions.

That's when I found the above snip, where it says SW_EN will be disabled if the fault condition occurs.

1. So, if the device switches to SLEEP because of tINACTIVE expiry is it considered as error conditions? Which interrupt flag would be set for this condition?

2. What are the other errors conditions and their respective flags which will be set which can result in SW_EN to be disabled?

Regards,

Punith Chandra

  • +1
    TI__Mastermind 27690 points

    Hi Punith,

    1. Yes it is considered as a fault. It will set CANSLNT flag in this case. The SW_EN bit should be set at the same time entering sleep mode (same SPI write). It is not recommended to have SW_EN set when the device is in any active mode such as normal mode. 

    2. It could be TSD, UVCC, frame overflow. There are corresponding interrupts in INT_1 and INT_2 registers. 

    Regards,

    Sean