Step 4: Build and flash

Important

west flash --recover and nrfutil device recover erase the whole chip, including the device credentials you install in step 5. Use them only for the first flash. After you have installed credentials, re-flash with a plain west flash, or with nrfutil device program without the recover command, to keep them.

Flash the host firmware on the host DK. Choose one of the following options:
- Build from source: Run the following commands inside the toolchain shell (step 2.4 in Set up the repository and toolchain), from smha-workspace/project. Pick the build for your host setup:
  
  nRF54L15 DK:
```
cd applications/ppp
west build -b nrf54l15dk/nrf54l15/cpuapp/ns -p
```
  nRF54LM20B DK:
```
cd applications/ppp
west build -b nrf54lm20dk/nrf54lm20b/cpuapp/ns -p
```
  nRF54LM20B DK + nRF7002-EB II:
```
cd applications/ppp
west build -b nrf54lm20dk/nrf54lm20b/cpuapp/ns -p -- \
  -DSHIELD=nrf7002eb2 \
  -DEXTRA_CONF_FILE=overlay-location.conf \
  -DSB_EXTRA_CONF_FILE=sysbuild-location.conf
```
  Then flash the host DK:
```
west flash --recover
```
- Pre-built firmware: Download the zip for your host setup from the latest release: ppp-nrf54l15-* for the nRF54L15 DK, ppp-nrf54lm20b-* for the nRF54LM20B DK, or ppp-nrf54lm20b-location-* for the nRF54LM20B DK with the nRF7002-EB II. Extract it, and flash merged.hex on the host DK. See Release artifacts for what the zip contains.
```
nrfutil device recover --serial-number <host_dk_serial_number>
nrfutil device program --firmware merged.hex --serial-number <host_dk_serial_number>
nrfutil device reset --serial-number <host_dk_serial_number>
```
Open a serial terminal at 115200 baud on the host console: VCOM1 on the nRF54L15 DK, VCOM0 on the nRF54LM20B DK.
Reset the host DK.
Note the Device ID in the boot log. You need it in step 5:
```
<inf> nrf_cloud_info: Device ID: E4361AD8FD3E4554
```
This 16-character hex ID comes from the host SoC hardware ID. It is not the nRF91 modem UUID.
Wait for the PPP link through the modem to come up.

Checkpoint: The console logs the following:

<inf> main: Network connected