BLE UART and Thread MTD CoAP Client Example

Table of Contents

• BLE-Thread switched MTD CoAP client example
• Setup
• Testing

This BLE-Thread switched multiprotocol example requires you to run the following example:

• Simple CoAP Server example

BLE-Thread switched MTD CoAP client example

This example application is based on the UART/Serial Port Emulation over BLE example available in nRF5 SDK. It has been modified to support switching between two connection modes, BLE and Thread:

• BLE mode – In this mode, the example works just like ble_app_uart, using Nordic's BLE UART Service.
• Thread mode – In this mode, the node that is running the example application starts attaching to a Thread mesh network. When the attachment procedure succeeds, the node sends a multicast CoAP message to toggle the LED on the simple_coap_server example board. After transmission of the CoAP message, the device switches back to the BLE mode.

The mode is switched from BLE to Thread in the following situations:

• Button 3 is pressed.
• String led is received through the Bluetooth connection.

The mode is switched from Thread to BLE in these situations:

• CoAP message containing the LED toggle request is sent.
• Thread timeout expires (10 seconds).

LED assignments:

• BSP_LED_0: Network state:
  • Blinking - BLE advertising.
  • Solid - Connected over BLE or over Thread.
• BSP_LED_1: Active network stack:
  • Disabled - BLE.
  • Solid - Thread.

Button assignments:

• BSP_BUTTON_0: Wake up from BLE Sleep mode.
• BSP_BUTTON_2: Switch protocol from BLE to Thread.

Interaction of ble_thread_switched_mtd_coap_client and simple_coap_server examples

Setup

You can find the source code and the makefile in the following folder: <InstallFolder>\examples\multiprotocol\ble_thread\ble_thread_swi_mtd_coap_cli

Testing

Note

The following procedure refers to using an Android smartphone. You can also use an iOS smartphone, but some screenshots can differ, pairing popups can appear, and for an iOS app you must ensure to convert all strings to ASCII HEX codes.

1. Prepare two nRF52840 Preview Development Kits and an Android smartphone.
2. On the smartphone, install nRF Connect for Mobile.
3. Run the following commands to flash the simple_coap_server example to one of the boards and switch it on. LED 1 starts blinking (attaching to a Thread network) and, after a few seconds, it turns solid (attached to a Thread network or Thread network created):

   $ cd <InstallFolder>/examples/thread/simple_coap_server/hex
   $ nrfjprog -f nrf52 -r --program nrf52840_xxaa.hex --chiperase

4. Build the example according to the instructions in Building examples.
5. Flash SoftDevice and the example according to the instructions in Running examples and switch the board on. LED 1 starts blinking (BLE advertising).
6. Open nRF Connect for Mobile and tap SCAN.
   

   nRF Connect for Mobile

   Note

   To auto-connect to the BLE device after it finishes operation on Thread network, select Use autoConnect in nRF Connect settings.

7. Tap CONNECT next to the Nordic_UART device. LED 1 on the ble_thread_switched_mtd_coap_client should be solid.
   

   nRF Connect for Mobile
8. Tap Nordic UART Service. The service information appear.
   

   nRF Connect for Mobile
9. Tap the arrow pointing up next to TX Characteristic. The Write value window appears.
   

   nRF Connect for Mobile
10. Enter the string led and tap SEND. The following happens:
    • LED 2 on the ble_thread_switched_mtd_coap_client board switches on for a few seconds and the client board starts the Thread attachment procedure.
    • When the Thread attachment procedure is finished, the client board sends a CoAP message to the simple_coap_server board through Thread.
    • When the message is received, the server board toggles LED 4.
    • The client board disconnects the Thread network and LED 2 switches off.
    • The client board starts BLE advertising, and LED 1 starts blinking.
11. When the ble_thread_switched_mtd_coap_client node starts advertising again, you can repeat the procedure starting from the step where you open nRF Connect for Mobile and tap SCAN.