topic Re: S32k3x wakeup using CAN receive in S32K

S32k3x wakeup using CAN receive

aadhi_402 — Wed, 08 May 2024 10:24:12 GMT

Dear NXP Team

MCU-S32K3xx

We are working for a project which needs to run the system in low power mode. So, our system should be in sleep/standby mode most of the time. And MCU needs to wakeup when there is a CAN message detected on the network. We have gone through few of the posts(Also in ref manual) in NXP, and found there is no direct source to wakeup the MCU from CAN. But we can do Multiplexing and using the same pin(PTA6(172 pin package)) for both CAN_RX and WKPU[15]. We also looked into the demo codes provided by NXP, we are trying to understand the demo codes. I don't think we can test this in simulation.

Is there any way to prove this behavior is working i.e we can wakeup MCU from CAN message ? Here we are blocking to go with this NXP S32K3xx MCU. If this cleared we can go with this MCU. Please clarify this. Let us know if i miss any details to provide.

Is there any other ways to wakeup the MCU with CAN message, by using CAN controller or external CAN transceiver.

One more thing, we can able to receive the first message itself and no miss of the first message right.

Thanks

Aadhi

Re: S32k3x wakeup using CAN receive

aadhi_402 — Wed, 08 May 2024 13:37:53 GMT

Hello Team,

Could you please respond ASAP, we need to finalize the micro immediately. Thanks.

Re: S32k3x wakeup using CAN receive

Julián_AragónM — Wed, 08 May 2024 20:12:51 GMT

Hi @aadhi_402,

FlexCAN itself is also not in Standby Power Domain, so you can't use the FlexCAN module directly to wake up the chip. But you can use the WKPU unit and the external pins. Refer to this post: Solved: S32K3 Wake up method - NXP Community. So yes, you can multiplex the pins to wake up the MCU, but it is not possible to simulate the MCU behavior, this needs to be tested with HW.

You can use these following examples as reference (S32DS 3.4 RTD 2.0.0): S32K3 Low Power Management AN and demos - NXP Community. There is a specific case for FlexCAN wake up.

The first CAN frame can't be fully received since there will be some time for the MCU to warm up from standby mode to run mode, so the application needs to ignore this CAN frame.

For the GPIO of S32K3, it can be set to multiple input functions simultaneously while it can be set to 1 output function (writing MSCR) at once. You can refer to the IO table attached to the S32K3's reference manual.

Also, as a note, if your inquiry is urgent, next time you enter a ticket please ensure that you use your company email address when communicating with NXP so that we can prioritize your question accordingly. Thank you for your understanding.

Best regards,
Julián

Re: S32k3x wakeup using CAN receive

aadhi_402 — Thu, 09 May 2024 12:33:30 GMT

@Julián_AragónM Thanks for your reply.

We have gone through the community post, which you have referred.

Do we need to have any wakeup patterns to wake up the MCU ?

Do we have any mechanism not to miss out the first frame ? Is this(Missing First Frame) common across the other MCUs as well ?

Can you suggest any other micro controller which can able to read/store the first message(not to miss any) when wake up ?

Can you refer us to the specific scenario in the given demo code, where we are waking up the MCU ?

Thanks

Aadhi

Re: S32k3x wakeup using CAN receive

Julián_AragónM — Thu, 09 May 2024 20:47:20 GMT

Hi @aadhi_402,

Are you referring to wake up sequences? The pdf attached to the S32K3 Low Power AN describes the required sequences for entering or exiting the different power modes in chapter 6 (Power Mode Entry/Exit).

This first missing frame is common in low power applications. Normally the first message is a wake-up frame or wake-up message/pattern.

The CAN controller will see the NACK and will automatically send the message again. This is known as automatic re-transmission and is a common feature on many CAN Controllers. This is behaviour is per CAN standard. If the message is not ACKed from another node it is transmitted repeatedly.

Could you clarify what is meant by "specific scenario"? The example configures the MCU for low power, and waits for the respective signal (GPIO, RTC, etc.) for wakeup (or fast wakeup).

Best regards,
Julián