diff --git a/examples/readme.md b/examples/readme.md
index f48e897d6..dc4c563dd 100644
--- a/examples/readme.md
+++ b/examples/readme.md
@@ -30,9 +30,16 @@ $ make BOARD=feather_nrf52840_express all
 
 ## Flash
 
-TODO: write more on flashing
+`flash` target will use the on-board debugger (jlink/cmsisdap/stlink/dfu) to flash the binary. We should install those debugger/programmer software in advance. Futhermore, since external jlink can be used with most of the board, there is also `flash-jlink` target for out convenience.
 
 ```
 $ make BOARD=feather_nrf52840_express flash
+$ make BOARD=feather_nrf52840_express flash-jlink
+```
+
+Some board use uf2 bootloader for drag & drop in to mass storage device, uf2 can be generated with `uf2` target
+
+```
+$ make BOARD=feather_nrf52840_express all uf2
 ```