nRF5340 Bluetooth Controller with Support for LE ISO Timesync

This fork of the Zephyr HCI UART example adds a custom HCI Command to allow for timesync between the Bluetooth Host and the Bluetooth Controller. When the HCI LE Read ISO Clock command is received, the Controller raise a GPIO for a few microseconds and returns its current Bluetooth LE ISO Clock in the Command Complete Event.

We raise the GPIO instead of just toggling as e.g. STM32F4xx only supports timer capture on a specific edge.

It has been tested on the nRF5340 Audio DK, but it should work with any nRF5340 dev kit.

Requirements

• nRF Connect SDK v2.8 or newer

HCI LE Read ISO Clock Command

• OGF: 0x3f, OCF: 0x200
• Parameters: Flags (1 Octet) unused
• Response: HCI Command Complete Event with status and 4 bytes timestamp in microseconds

nRF58233 Development Kit

The first Virtual UART (UART1, ...) is Zephyr UART 0 The second Virtual UART (UART2, ...) is Zephyr UART 1

Pinout

Signal direction as seen from the nRF52833.

PIN	Arduino	MCU	Direction
TX	D0	P0.05	out
RX	D1	P0.06	in
RTS	D7	P0.07	out
CTS	D8	P0.08	in
Time Sync	D10	P1.01	out

HCI over UART 0 connected to first Virtual UART in J-Link Probe

Release build:

west build --pristine -b nrf52833dk/nrf52833

Debug build:

west build --pristine -b nrf52833dk/nrf52833 -- -DOVERLAY_CONFIG=debug.conf

To use UART 0 via Arduino headers, the virtual UART of the J-Link probe needs to be disabled, e.g. with the JLink Configuration Tool.

nRF5340 Development Kit

The first Virtual UART (UART1, ...) is Zephyr UART 1 The second Virtual UART (UART2, ...) is Zephyr UART 0

Pinout

Signal direction as seen from the nRF5340.

PIN	Arduino	MCU	Direction
TX	D0	P1.00	out
RX	D1	P1.01	in
RTS	D7	P1.11	out
CTS	D8	P1.10	in
Time Sync	D10	P1.06	out

HCI over USB CDC

west build --pristine -b nrf5340dk/nrf5340/cpuapp -- -DEXTRA_DTC_OVERLAY_FILE=usb.overlay -DOVERLAY_CONFIG=overlay-usb.conf

HCI over UART 0 connected to second Virtual UART in J-Link Probe

west build --pristine -b nrf5340dk/nrf5340/cpuapp

• HCI over second Virtual port / UART 0
• Boot banner on Arduino Header UART (P1.01) / UART 1

HCI over UART 1 connected to first Virtual UART in J-Link Probe as well as Arduino Headers

west build --pristine -b nrf5340dk/nrf5340/cpuapp -- -DEXTRA_DTC_OVERLAY_FILE=uart1.overlay

• No Boot Banner on Arduino Header UART

nRF5340 Audio DK

The first UART (UART1, P1.04, P1.05) is only available via test points (TP60, TP61, ...) The second UART (UART2, P1.08, P1.09) is connected to the Arduino headers.

Pinout

Signal direction as seen from the nRF5340.

PIN	Arduino	MCU	Direction
TX	D0	P1.09	out
RX	D1	P1.08	in
RTS	D7	P1.11	out
CTS	D8	P1.10	in
Time Sync	D10	P1.01	out

HCI over USB CDC

west build --pristine -b nrf5340_audio_dk/nrf5340/cpuapp -- -DEXTRA_DTC_OVERLAY_FILE=usb.overlay -DOVERLAY_CONFIG=overlay-usb.conf

HCI over UART 0 connected to Virtual UART in J-Link Probe

west build --pristine -b nrf5340_audio_dk/nrf5340/cpuapp

HCI over UART 1 connected to Virtual UART in J-Link Probe as well as Arduino Headers

Release build:

west build --pristine -b nrf5340_audio_dk/nrf5340/cpuapp -- -DEXTRA_DTC_OVERLAY_FILE=uart1.overlay

Debug build:

west build --pristine -b nrf5340_audio_dk/nrf5340/cpuapp -- -DEXTRA_DTC_OVERLAY_FILE=uart1.overlay -DOVERLAY_CONFIG=debug.conf

To use UART 1 via Arduino headers, the virtual UART of the J-Link probe needs to be disabled, e.g. with the JLink Configuration Tool.

nRF54L15

HCI over UART 1 connected to second Virtual UART in J-Link Probe

In Zephyr, the following DTS entry select the UART: zephyr,bt-c2h-uart = &uart20. (It's not clear, why it's called uart20, but data is routed over UART 1 w.r.t to nRF4L15 Hardware User Guide)

Release build:

west build -d nrf54l15-iso --pristine -b nrf54l15dk/nrf54l15/cpuapp

Debug build:

west build -d nrf54l15-iso --pristine -b nrf54l15dk/nrf54l15/cpuapp -- -DOVERLAY_CONFIG=debug.conf

To use UART 1 via pin headers, the virtual UARTs of the J-Link probe need to be disabled, e.g. with the JLink Configuration Tool. As you might want to change the VDDM voltage, see next section, you can also use the Board Configurator GUI to disable VCOM1 and set VDDM.

nRF54L15 Power Supply

Warning: On the nRF45L15 DK, the VDDM for the nRF54L15 is set to 1.8V by default!

Options to use it with 3.3V Bluetooth Host:

• Use the Board Configurator GUI, which is part of nRF Connect for Desktop, to change the VDDM to 3.3V
• remove the jumper from VDDM Current Measurement connector (P6) and connect 3.3V to VDDM (middle pin).

Pinout

Signal direction as seen from the nRF54L15.

PIN	MCU	Direction
TX	P1.04	out
RX	P1.05	in
RTS	P1.06	out
CTS	P1.07	in
Time Sync	P1.11	out

Maintainer Notes

• nRF5340 use Controller configuration in sybuild/ipc_radio/prj.conf, while others, e.g. nRF54L15, use configuration from prj.conf. Please update both at the same time.
• We can detect nRF5340 SoC in CMake with if(CONFIG_SOC STREQUAL "nrf5340") after find_package zephyr.