Hi,
My nRF51802QFAA Module without an external 32khz oszillator.
I use SDK 12.3.0 with keil,the ble_app_uart template works well the configs as below.
#define NRF_CLOCK_LFCLKSRC {.source = NRF_CLOCK_LF_SRC_RC, \
.rc_ctiv = 16, \
.rc_temp_ctiv = 2, \
.xtal_accuracy = NRF_CLOCK_LF_XTAL_ACCURACY_20_PPM}
but the experimental_ant_bootloader and bootloader_secure/pca10028 template can not wrok,I have experience with 52832 DFU and I tried many ways, but it didn't work.
my bootloader_secure/pca10028 configs for keil:

I bulid it according to your experimental_ant_bootloader template,It also has a DFU service successful,However, Dfutarg broadcast cannot into.

And Is this script right with nRF51802QFAA?
nrfutil settings generate --no-backup --family NRF51 --application app.hex --application-version 1 --bootloader-version 1 --bl-settings-version 1 settings.hex
mergehex --merge bootloader.hex settings.hex --output bl_temp.hex
mergehex --merge bl_temp.hex app.hex s130_nrf51_2.0.1_softdevice.hex --output BLE_Latest.hex
nrfutil pkg generate --hw-version 52 --sd-req 0x87 --application-version 1 --application app.hex --key-file private.pem BLE_ota.zip


