How to modify the device information through BLE connection

In this blog, it shows how to modify the device parameters through the BLE connection. The example has included the NUS service, Battery Service and Thingy configuration service (TCS). On top of the TCS, some extra characteristic are added such as TX power, advertising content for non-connectable advertising) and password protection.

In additional, I provide a method how to dynamic change the advertising payload without restart the advertising module. The idea is to use the pointer instead of copying the value.

All the BLE characteristic of Thingy Configuration Services are showed as below.

  • Device Name
  • Advertising interval
  • Connection interval (Minimum and Maximum interval)
  • FW version (read)
  • MTU size
  • TX Power
  • Connection Protection Password
  • Advertising content (non-connectable advertising)
  • Verify the Password

All the parameters would be stored at the internal flash of nRF52 through FDS module.

Details on the implementation

Change the Device Name

#define DEVICE_NAME            "UART_ADV"                                    /**< Name of device. Will be included in the advertising data. */

The maximum length of the device name is 10 bytes.
The default device information is configured at THINGY_CONFIG_DEFAULT.
Configure the device name at gap_params_init


How to measure the battery information on the device

Select the VDD pin to check on the value through SAADC.
Read the battery on every 2 seconds.
Configure the SAADC to select the channel.

How to set the TX Power during the advertising

On the nrF52832, it has supported the following TX Power setting.

How to set the Password / Verify the Password after connection

  • pwd_char_add — read/write for 4 digits password protection
  • pwd_verify_char_add — use for verify the password

For the password verification, it is controlled by the compile switch at the sdk_config.h. The host needs to send/write the correct 4 digit password for verification within first 30 seconds (NRF_PWD_TIMEOUT_PERIOD) after connection. Otherwise, the BLE link is automatically disconnected.

Compare with the stored key.
The link would be disconnected after timeout.

How to set the non-connectable advertising payload

On this example, it supports two difference advertising mode.

  1. Non-connectable advertising
  2. Connectable undirected advertising

By pressing the button 0 during the power up, the device would run as the connectable advertising mode.

Dynamic change the Advertising content without stop/start the advertising module

Background

During the advertising init, you need to specify all the advertising parameter and then call the routine ble_advdata_encode. After that it passes the encoded data on the advertising payload.

Instead of dynamic change the advertising content, you can hardcode the enc_advdata.

And then, pass the hardcode_enc_adadata to the advertising module.

Requirement

  • SDK 15.3 / S132v6.1.1
  • NRF52832 DK
  • IDE: Segger Embedded Studio

Source Code:

https://github.com/jimmywong2003/nrf5-modify-device-parameter-through-host

2 thoughts on “How to modify the device information through BLE connection

  1. I don’t even know how I ended up here, but I thought this post
    was great. I don’t know who you are but certainly you’re going to
    a famous blogger if you aren’t already 😉 Cheers!

    Like

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