User interface

All nRF5340 Audio applications implement the same, simple user interface based on the available PCB elements of the nRF5340 Audio development kit. You can control the application using predefined switches and buttons while the LEDs display information.

Some user interface options are only valid for some nRF5340 Audio applications.

Switches

The application uses the following switches on the supported development kit:

Switch	Function	Applications
POWER	Turns the development kit on or off.	All
DEBUG ENABLE	Turns on or off power for debug features. This switch is used for accurate power and current measurements.	All

Buttons

The application uses the following buttons on the supported development kit:

Button	Function	Applications
VOL-	Long-pressed during startup: Changes the headset to the left channel one.	nRF5340 Audio: Broadcast sink nRF5340 Audio: Unicast server
	Pressed on the headset or the CIS gateway during playback: Turns the playback volume down.	nRF5340 Audio: Broadcast sink nRF5340 Audio: Unicast server nRF5340 Audio: Unicast client
VOL+	Long-pressed during startup: Changes the headset to the right channel one.	nRF5340 Audio: Broadcast sink nRF5340 Audio: Unicast server
	Pressed on the headset or the CIS gateway during playback: Turns the playback volume up.	nRF5340 Audio: Broadcast sink nRF5340 Audio: Unicast server nRF5340 Audio: Unicast client
PLAY/PAUSE	Starts or pauses the playback of the stream or listening to the stream.	All
BTN 4	Long-pressed during startup: Turns on the DFU mode, if the device is configured for it.	All
	Pressed on the gateway during playback: Toggles between the normal audio stream and different test tones generated on the device. Use this tone to check the synchronization of headsets.	nRF5340 Audio: Broadcast source nRF5340 Audio: Unicast client
	Pressed on the gateway during playback multiple times: Changes the test tone frequency. The available values are 1000 Hz, 2000 Hz, and 4000 Hz.
	Pressed on a BIS headset during playback: Change stream (different BIS), if more than one is available.	nRF5340 Audio: Broadcast sink
BTN 5	Long-pressed during startup: Clears the previously stored bonding information.	nRF5340 Audio: Unicast server nRF5340 Audio: Unicast client
	Pressed during playback: Mutes the playback volume.	nRF5340 Audio: Unicast server nRF5340 Audio: Unicast client
	Pressed on a BIS headset during playback: Change the gateway, if more than one is available.	nRF5340 Audio: Broadcast sink
RESET	Resets the device to the originally programmed settings. This reverts any changes made during testing, for example the channel switches with VOL buttons.	All

LEDs

To indicate the tasks performed, the application uses the LED behavior described in the following table:

LED	Indication	Applications
LED1	Off - No Bluetooth connection.	All
	Solid blue on the CIS gateway and headset: Kits have connected.	nRF5340 Audio: Unicast server nRF5340 Audio: Unicast client
	Solid blue on the BIS headset: Kits have found a broadcasting stream.	nRF5340 Audio: Broadcast sink
	Blinking blue on headset: Kits have started streaming audio (BIS and CIS modes).	nRF5340 Audio: Broadcast sink nRF5340 Audio: Unicast server
	Blinking blue on the CIS gateway: Kit is streaming to a headset.	nRF5340 Audio: Unicast client
	Blinking blue on the BIS gateway: Kit has started broadcasting audio.	nRF5340 Audio: Broadcast source
LED2	Off - Sync not achieved.	All
	Solid green - Sync achieved (both drift and presentation compensation are in the LOCKED state).	nRF5340 Audio: Broadcast sink nRF5340 Audio: Unicast server
LED3	Blinking green - The nRF5340 Audio DK application core is running.	All
CODEC	Off - No configuration loaded to the onboard hardware codec.	All
	Solid green - Hardware codec configuration loaded.	All
RGB (bottom side LEDs around the center opening)	Solid green - The device is programmed as the gateway.	nRF5340 Audio: Broadcast source nRF5340 Audio: Unicast client
	Solid blue - The device is programmed as the left headset.	nRF5340 Audio: Broadcast sink nRF5340 Audio: Unicast server
	Solid magenta - The device is programmed as the right headset.	nRF5340 Audio: Broadcast sink nRF5340 Audio: Unicast server
	Solid yellow - The device is programmed with factory firmware. It must be re-programmed as gateway or headset.	All
	Solid red (debug mode) - Fault in the application core has occurred. See UART log for details and use the RESET button to reset the device. In the release mode, the device resets automatically with no indication on LED or UART.	All
ERR	PMIC error or a charging error (or both). Also turns on when charging the battery exceeds seven hours, since the PMIC has a protection timeout, which stops the charging.	All
CHG	Off - Charge completed or no battery connected.	All
	Solid yellow - Charging in progress.
OB/EXT	Off - No 3.3 V power available.	All
	Solid green - On-board hardware codec selected.
	Solid yellow - External hardware codec selected. This LED turns solid yellow also when the devices are reset, for the time then pins are floating.
FTDI SPI	Off - No data is written to the hardware codec using SPI.	All
	Yellow - The same SPI is used for both the hardware codec and the SD card. When this LED is yellow, the shared SPI is used by the FTDI to write data to the hardware codec.
IFMCU (bottom side)	Off - No PC connection available.	All
	Solid green - Connected to PC.
	Rapid green flash - USB enumeration failed.
HUB (bottom side)	Off - No PC connection available.	All
	Green - Standard USB hub operation.