Hi @Asmita
First I’ll talk about your second post
On document Gateway Quick Development Guide you have all instructions to setup a DRTLS systems. You need at least 6 boards DWM1001-DEV:
- 1 Initiator
- 3 Anchors
- 1 Tag
- 1 Gateway
To setup the Gateway you’ll need a Raspberry Pi 3 Model B.
Following the instructions, at end you will see your tag and anchors on your screen.
Now, that you are with your DRTLS working fine, let’s move to your first post.
Please, see my question about this here [1]. I want to connect others sensors and one button on the board and change messages with gateway through MQTT server. To do this you have a “space” on the flash memory for a user program. To do this see examples below DWM1001\Source_Code\DWM1001_on_board_package directory. In my post [1], @Weibo_Pan give a very detailed explanation.
To do everything working together in your board, please see document DWM1001 Firmware
User Guide.
Finally about functions dwm_shell_compile(), dwm_le_compile(), dwm_serial_spi_compile(), I also don’t know (yet) why they are there and what exactly they do. For now, I’m just using it as a “dogma” 
It will be great if anyone can explain it to us.
All the best
[1] Sending Accelerometer data, and data from other sensors through MQTT - #2 by Weibo_Pan