https://devzone.nordicsemi.com/f/nordic-q-a/37536/buttonless_dfu-can-t-work-with-gnu-in-nrf51822Hi, I use SDK 12.3 to run experimental_ble_app_buttonless_dfu on nrf51822 after reference this blog , but still can not work. It works fine with PCA10028 board. I want to open log to see what happened, but log function can&#39;t work in PCA10028 oren-USTelligent Community 13Thu, 16 Aug 2018 12:19:36 GMThttps://devzone.nordicsemi.com/thread/144529?ContentTypeID=1Thu, 16 Aug 2018 12:19:36 GMT137ad170-7792-4731-bb38-c0d22fbe4515:a7fa2715-2966-414f-9843-52f56a4a62a3Einar Thorsrud<p>Hi,</p> <p>1. Do you want logging in the bootloader or application? If you want logging in the bootloader, use the project you can find under &lt;SDK 12.3&gt;\examples\dfu\bootloader_secure\pca10028_debug\. This has a sdk_config.h file that enables RTT logging. Note that it is also a bit larger than the project without logging, so the flash start address is lower than the normal project (without the _debug suffix). If you want logging in the experimental_ble_app_buttonless_dfu&nbsp; application, you need to enable it in sdk_config.h.</p> <p>2. SDK 12.3 comes with support for nRF52822. You can find the example project under &lt;SDK 12.3&gt;\examples\ble_peripheral\experimental_ble_app_buttonless_dfu\pca10028\. It should work out of the box. Can you elaborate how it does not work in your case?</p><div style="clear:both;"></div>