https://devzone.nordicsemi.com/f/nordic-q-a/62916/can-i-control-csn-pin-as-output-in-slave-mode-on-nrf52840I think spi slave pins should set as input but I want to control CSN pin as output in spi slave mode on nrf52840. Is it possible it? I know that CSN pin is controlled by external chip but my external chip can not control it. so I want to control iten-USTelligent Community 13Tue, 23 Jun 2020 11:56:28 GMThttps://devzone.nordicsemi.com/thread/256421?ContentTypeID=1Tue, 23 Jun 2020 11:56:28 GMT137ad170-7792-4731-bb38-c0d22fbe4515:83cc1241-cceb-47f0-b8e0-7c3c43972555Karl Ylvisaker<p>Hello,<br /><br />The SPI protocol specification dictates the behavior of a SPI slave device, and it may not be the one controlling the slave select pin.<br />The slave select pin is used by the SPI master device to initiate comunication with specific devices on a bus shared by multiple slaves - it would therefore violate the SPI specification and possibly cause lock-ups and errorous communication if a slave was to control the slave select bus.<br /><br />How many devices is sharing the SPI bus in question, and what is the design reason behind why you would like the SPI slave to controll the slave select pin?<br />If you can elaborate more on the use-case / the functionality you would like to achieve I can advice you on how to implement it.<br /><br />Best regards,<br />Karl</p><div style="clear:both;"></div>