https://devzone.nordicsemi.com/f/nordic-q-a/71615/using-cypress-s25fs512s-as-qspi-block-deviceI am using the nRF52840 (with SDKv17.0.0 + s140_7.0.1) and made a custom FW based on the ble_app_hrs example. My custom HW has a 64MB S25FS512S flash memory chip. I found this ticket which use either 32MB or 128MB (256MB?) flash memory as QSPI blocken-USTelligent Community 13Mon, 15 Feb 2021 12:46:57 GMThttps://devzone.nordicsemi.com/thread/294380?ContentTypeID=1Mon, 15 Feb 2021 12:46:57 GMT137ad170-7792-4731-bb38-c0d22fbe4515:acfe7431-0ca2-4063-9712-83f4f0cd52e6Kenneth<p>I don&#39;t expect they have considered the sectors sizes may differ over the flash, so unless you want to modify the lower layer driver, I expect that you will need to choose a NOR flash with fixed sector size.&nbsp;Macronix MX66 and MX25 devices should all work.</p><div style="clear:both;"></div>