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TIOL1113: Master Wakeup TIOL

Adrian Ymeraj
Expert 3770 points
Part Number: TIOL1113

Hello team,

I have a question regarding the TIOL1113: In particular I have a question about the Wakeup signal generated by the TIOL when the Master intends to activate the IO-Link communication.
From datasheet I infer that the Enable EN pin must be high for the TIOL to activate the Wakeup (Table 4 page 14).
And in fact I verified that Wakeup is activated only if EN is at a high logical level.
The C / Q output can also be used as an N-Switch or P-Switch and page 17 it is written to use the EN to perform the open and closed function in this mode.
If I am in this state and the output is not active, the EN pin must be low.
If the master intends to start an IO-Link communication and activates the short circuit on the CQ line for the duration of 80us, in these conditions how does the TIOL activate the Wakeup if EN is equal to 0?

Thanks for the support.

Best regards,

Adrian

  • 0
    TI__Mastermind 24460 points

    Hi Adrian,

    You are correct in your understanding of how the TIOL1113 handles the Wake-up pulse.  This is an issue that has come up with different interpretations of the standard and how the purpose of the Wake-up pulse.  The TIOL1113 was designed according to the functionality defined in the standard.  Unfortunately the functionality you are asking about is not discussed in the standard, but we are aware that other IO-Link devices do pass the Wake-Up pulse on the WAKE pin when the EN pin is low.

    As described in the standard, when the device is in SIO mode and actively driving the CQ line, the Master is unable to send data on the line to the device without telling the device it needs to first stop driving the bus and disable it's output.  This is done by the Master sending the Wake-Up pulse on the CQ line.  When the Device detects this pulse it sends the indication to the MCU on the WAKE pin.  This is where the standard stops it's description of the WAKE pin functionality and does not define any behavior or expectation when the EN pin is already low and the Master tries to send a Wake-Up pulse on the line.

    The TIOL1113 was designed such that when the EN pin is low, there is no need for the MCU to respond to the Wake-Up pulse because the TIOL1113 is already capable of receiving data from the Master.  Therefore it does not send a pulse to the MCU on the WAKE pin.

    However, we know that since other IO-Link devices are designed to pass a Wake-up pulse on their WAKE pins regardless of their Driver status, that many MCU firmware stacks expect this pulse to always be present at the beginning of a communication message.  This is used as a form of interrupt. 

    From a physical layer perspective this use of the WAKE pin is not defined, but we now understand how desirable this function is from a firmware perspective.  We are looking into implementing this in our future devices.

    However, for now, the TIOL1113's RX pin will always reflect the value on the CQ pin.  When EN is low, the Master controls the voltage on the CQ pin and when it sends a Wake-up pulse, this too will be passed to the MCU on the RX pin.  Typically a slight firmware modification is used to monitor the RX pin for the Wake-Up pulse when EN is low.  This is fairly straight forward and the typical solution that only requires a few lines of extra code.

    If there are reasons that the MCU is unable to implement a firmware solution that monitors the RX pin, then a simple logic circuit can be used to combine the WAKE and RX outputs when the EN pin is low.

    Regards,

    Jonathan