CAN wake up in SBC UJA1169A

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CAN wake up in SBC UJA1169A

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victor_pompido
Contributor I

Hello all,

I´m in a project working with the "SBC" UJA1169A. When I put the SBC in standby or sleeep mode, the CAN transcevier goes to offline. In that state, I need to wake up the transceiver with a "dominant-recessive-dominat" wake-up. 

the question is:

If I use a normal CAN frame to achive the wake-up, the information of the payload of that signal is lost? Shall I send always a wake-up signal and then the first "important" signal or just sending the important signal(achiving the wake-up) si enough?

Best regards,

Victor

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TomasVaverka
NXP TechSupport
NXP TechSupport

Hi Victor,

Normal CAN frame should be: Start of Frame (1 bit Dominant) -> ID (11bits, ID number), therefore, it may not be equal as Wake up pulse pattern.

After Wake up detection by host controller (checking RXD), the controller send MC=111 to set UJA1169A to Normal mode and CAN control mode enters to CAN Active mode, but delay to make CAN Active mode takes tstartup(CAN)<220us (CTS=1 is indicated when UJA1169A enters CAN Active mode).

So, many bytes of CAN data would be lost until UJA1169A entered to CAN Active mode and received data appears at RXD, if UJA1169A had to wake up by normal CAN frame.

Best regards,

Tomas

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