SWRU301

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3.6 Device Discovery

Before the two devices can connect, the central device must first discover the

peripheral device. To perform device discovery, press up on joystick U1 once. The

LCD on the central device should display “Discovering…”.

After a few seconds, it should display “Devices Found 1 / <- To Select”. This means

that the central device successfully discovered the peripheral. Press left on joystick

U1 to view the address of the peripheral device. This address should match the

address seen on the peripheral’s LCD.

3.7 Establish Connection

To establish a connection with the peripheral, press joystick U1 in towards the

board (push it inwards, like it is a button). Once the connection is established,

the central device will automatically perform service discovery on the peripheral

using the BLE GATT protocol. This should complete within a few seconds.

The two LCD screens should appear as in the images below, with the central still

displaying the peripheral’s address and the peripheral having changed from

“Advertising” to “Connected”:

Be careful that you don’t “double tap” U1 which would terminate the connection immediately, giving

Disconnected Reason: 22.

3.8 Connected Operations

Once the connection has been established and service discovery is complete, you can perform the

following operations using joystick U1 on the central device:

UP:

Read / Write Data

RIGHT: Connection Parameter Update

DOWN: RSSI Monitoring

IN:

Terminate Link

3.9 Read / Write Data

Pressing up on U1 will send a read request to the peripheral device. One byte of data will be read, and the

value will be displayed. Pressing up again will send a write request, and one byte of data will be written to

the peripheral. The peripheral’s LCD should display the written value each time this is done.

Bluetooth low energy is an ideal technology for transmission of small amounts of data between two

devices while consuming very little power, as is demonstrated here.

Continuing to press up on the joystick will alternate between reads and writes, with the value

incrementing each time.