https://devzone.nordicsemi.com/f/nordic-q-a/124076/pa21540-spi-interface-questionhi support team, customer is preparing to use 21540, only use gpio mode, not using spi interface, may i ask how to deal with spi pins of 21540, float or pull up to vdd? Regards, William.en-USTelligent Community 13Tue, 02 Sep 2025 11:47:25 GMThttps://devzone.nordicsemi.com/thread/547456?ContentTypeID=1Tue, 02 Sep 2025 11:47:25 GMT137ad170-7792-4731-bb38-c0d22fbe4515:190818ba-2f2d-4ff4-a41a-82819e0e1c01Bendik Heiskel<p>Hi William,</p> <p>Due to <a href="https://docs.nordicsemi.com/bundle/errata_nRF21540_Rev2/page/ERR/nRF21540/Rev2/latest/anomaly_540_13.html">errata 13</a>&nbsp;all the input pins of the nRF21540 needs to be pulled low when the device is in power down. This the SCK, MOSI pin of the SPI interface can be directly connected to GND. The CSN pin needs to be high when the&nbsp; device is powered on, but low when power off, so the CSN pin can be connected to the PDN pin to achieve this. The MISO pin is a output from the nRF21540 so this pin should be left floating when the SPI interface is not used.</p> <p>&nbsp;</p> <p>Best regards,<br />Bendik</p><div style="clear:both;"></div>