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Associate III
August 4, 2020
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ST25R95 IRQ_In low pulse?

  • August 4, 2020
  • 1 reply
  • 566 views

Hello ,

According to the st25r95 datasheet:

"After the power supply is established at power-on, the ST25R95 waits for a low pulse on the pin IRQ_IN (t1) before automatically selecting the external interface (SPI) and entering Ready state after a delay".

I have a custom board and I want to read the device id over spi, but the IRQ_IN pin is not connected.

Can it work without IRQ_IN low pulse? Can I communicate with the device, currently I have nothing on MISO line.

    This topic has been closed for replies.
    Best answer by Brian TIDAL

    Hi,

    IRQ_IN needs to be connected and needs to follow the power up sequence. SPI communications can only be performed once the power up sequence is completed.

    IRQ_OUT is recommended to be connected as well.

    X-CUBE-NFC3 firmware uses both IRQ_IN and IRQ_OUT.

    Rgds

    BT

    1 reply

    Brian TIDAL
    Brian TIDALBest answer
    Technical Moderator
    August 4, 2020

    Hi,

    IRQ_IN needs to be connected and needs to follow the power up sequence. SPI communications can only be performed once the power up sequence is completed.

    IRQ_OUT is recommended to be connected as well.

    X-CUBE-NFC3 firmware uses both IRQ_IN and IRQ_OUT.

    Rgds

    BT

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