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TCAN2451-Q1: May I use the 4ch wake-up inputs as a general digital input and transfer to MCU via SPI communication, not wake-up?

Bing Li
Prodigy 50 points
Part Number: TCAN2451-Q1

Tool/software:

The TCAN2451-Q1 has the 4ch wake-up inputs and it has the wake-up feature. My questions are,

1. may I just use the 4ch wake-up as the general digital inputs without wake-up feature, and state of the 4ch inputs is transferred to MCU via the SPI communication?

2. For 4ch wake-up inputs, could I disable the internal pullup which is connected with VSUP?

3. The integrated CAN communication need to support wake-up feature. Does the wake-up event send to MCU via SPI communication, not via nINT?

  • 0
    TI__Mastermind 26806 points

    Bing,

    Yes, you can read the status of these pins via SPI, but keep in mind you should use the LWU_EN bit to mask the LWU interrupt so that changes on this pin are not indicated on nINT (unless this is desired).

    You can use WAKE_IDx_PU_PD = 00b to turn off the pull-up/pull-down across all states of the pin. However, the pull-up/pull-down should only be active if this pin becomes configured as an ID pin.

    When the device wakes up, it will indicate the wake-up to the MCU by activating the supplies (if programmed), and also by asserting nINT. The device does not have the capability to operate as a SPI controller. It is only a SPI target/slave.

    Best,

    Danny

  • 0 in reply to Danny Bacic
    Prodigy 50 points

    Hello Danny

    Thanks for your reply on my questions. 

    Regarding the 3rd question, I think I have the wrong description. The CAN wake-up can be done via RxD pull down activation. You can skip this question.

    Then, if the WAKE_IN does not request wake-up feature, the nINT pin can leave open, right?

  • 0 in reply to Bing Li
    TI__Mastermind 26806 points

    Bing,

    The nINT pin also indicates other interrupts, which are listed in the Register Maps section of the data sheet. Look for anything in the INT_GLOBAL register 0x50. These will be indicated on nINT.

    Best,

    Danny

  • 0 in reply to Danny Bacic
    Prodigy 50 points

    Hello Danny

    Follow your comments, I checked all these events triggering interrupt can be transferred via SPI communication, so the nINT connection to MCU is not necessary, right?

    Do you know any mandatory events which must delivery vis nINT pin?

    Thanks.

  • 0 in reply to Bing Li
    TI__Mastermind 26806 points

    Bing,

    It depends on what your system needs to know. For many of the events listed in INT_GLOBAL (i.e. registers 0x51, 0x52, 0x53, 0x54, 0x55, 0x5A, 0x5C), this could be the only way they're indicated. You can check these by polling the device as well, but without connection to the nINT pin, you might lose the ability for the device to generate interrupts to the MCU.

    Best,

    Danny