Hardware description¶
This section of the documentation specifies and describes the nRF54L15 Connect Kit mainly from a hardware point of view.
Hardware diagram¶
The following figure illustrates the nRF54L15 Connect Kit hardware diagram. The design has loose or pre-soldered pin headers available.
Mechanical dimensions¶
The nRF54L15 Connect Kit is a 4-layer chem. Gold, 55.88mm x 20.32mm (2.2" x 0.8") 1mm thick PCB with a USB Type-C port, LEDs, Buttons, U.FL receptacles and 40x castellated/through-hole pins.
Power supply¶
The nRF54L15 Connect Kit can be powered through either the USB-C port or the VSYS pin (1.8-5.5V input range). The board contains a TPS63901 buck-boost converter with 75-nA quiescent current and 1.8V/3.3V configurable power supply for I/Os.
The following figure describes the power supply architecture:
VBUS is the 5V input from the USB-C port. There are two parallel Schottky diodes between VBUS and VSYS, which add flexibility by allowing power ORing of different supplies into VSYS.
Set ENABLE HIGH to enable VDD_GPIO output and LOW to disable VDD_GPIO output. This pin has a pull-up resistor (1MOhm) and can be tied to GND to place the board in Power-Down mode.
IF_P0.8 controls VDD_GPIO voltage selection: HIGH = 1.8 V, LOW = 3.3 V. This pin has a pull-down resistor (1MOhm), which sets the default VDD_GPIO voltage to 3.3 V.
Powering the board
The nRF54L15 Connect Kit features flexible power management, supporting USB-C, external power supplies, or batteries.
This is the simplest way to power the board, which will power VSYS (and therefore the system) from the 5V USB VBUS voltage, through two internal Schottky diodes (so VSYS becomes VBUS minus the Schottky diode forward voltage).
If the USB-C port is NOT going to be used, it is safe to power the board by directly connecting VSYS to your preferred power source (in the range 1.8V to 5.5V).
To safely add a second power source to the board, simply feed VSYS through an external Schottky diode.
An improved way to power from a second source is using an external P-MOSFET to replace the Schottky diode as shown in the following figure.
The nRF54L15 Connect Kit can be also used with a battery charger with power path manager which will automatically and seamlessly switch between the input source and the battery power.
Interface MCU¶
The nRF54L15 Connect Kit features an nRF52820-based Interface MCU that enables onboard debugging and programming, eliminating the need for external tools. The Interface MCU also includes a USB-UART bridge for log, trace and terminal emulation, and an Interface Shell bundled with helpful commands to access the board-specific functionality.
The following figure describes the functional architecture of the Interface MCU:
The following table describes the pin functions of the Interface MCU:
| Pin name | Description |
|---|---|
| P0.0 | GPIO pin used for SWCLK output. Connect to the SWCLK pin of nRF54L15. |
| P0.1 | GPIO pin used for SWDIO input/output. Connect to the SWDIO pin of nRF54L15. |
| P0.2 | General purpose I/O. SDA pin of the I2C bus. |
| P0.3 | General purpose I/O. SCL pin of the I2C bus. |
| P0.4/RX | RXD pin of the UART bridge. Connect to the P0.0 pin of nRF54L15. |
| P0.5/TX | TXD pin of the UART bridge. Connect to the P0.1 pin of nRF54L15. |
| P0.7 | GPIO pin used for RESET output. Connect to the RESET pin of nRF54L15. |
| P0.8 | GPIO pin used to select the voltage of VDD_GPIO. Connect to the SEL pin of TPS63901 through a 1-MΩ pulldown resistor. Selects 1.8V when a high level is applied to this pin. Selects 3.3V when a low level is applied to this pin. |
| P0.14 | GPIO pin used to control the Blue LED of RGB LED driven by a MOS switch. A high level applied to this pin turns on the LED and a low level turns it off. |
| P0.15 | GPIO pin used to control the Green LED of RGB LED driven by a MOS switch. A high level applied to this pin turns on the LED and a low level turns it off. |
| P0.20 | GPIO pin used to control the Red LED of RGB LED driven by a MOS switch. A high level applied to this pin turns on the LED and a low level turns it off. |
| P0.30 | GPIO pin used to detect button press of the DFU/RST button. This pin pulls to GND when the button is pressed. |
General purpose I/Os¶
There are up to 31 multi-function General Purpose I/Os (8 can be configured as ADC inputs) available on the header pins. These GPIOs are powered from the VDD_GPIO rail which is 1.8V or 3.3V configurable.
Dedicated pins
Some pins on the device are dedicated for a specific purpose. GPIO pin routing and configuration is flexible. Some pins have limitations or recommendations for configuration and use. For details, see Pin assignments.
The following figure illustrates the GPIOs pinout:
Buttons¶
The nRF54L15 Connect Kit has two on-board push-buttons, one labeled with USR is connected to the P0.3 of nRF54L15, the other labeled with DFU/RST is connected to the P0.30 of the Interface MCU (nRF52820).
The following table describes the function of the buttons:
| Button | GPIO | Description |
|---|---|---|
| USR | P0.3 nRF54L15 | User programmable push-button controlled by nRF54L15. The P0.3 pin pulls to GND when the button is pressed |
| DFU/RST | P0.30 nRF52820 | This push-button is controlled by nRF52820 and its behavior depends on the Interface MCU firmware. The P0.30 pin pulls to GND when the button is pressed. Push and hold this button and then power up the board, the board will run into the Interface MCU UF2 Bootloader Mode. In Interface MCU Normal Mode, pushing this button resets the nRF54L15. |
LEDs¶
The nRF54L15 Connect Kit has one Green LED controlled by nRF54L15 and one RGB LED controlled by the Interface MCU (nRF52820). Each LED is driven by a MOS switch and powered from the VSYS rail. A high level applied to the GPIO pin turns on the LED and a low level turns it off.
The following figure shows the connection and behavior of each LED:
| LED | GPIO | Description |
|---|---|---|
| Green LED | P0.2 nRF54L15 | User programmable LED. |
| RGB LED - Green | P0.15 nRF52820 | Indicates the UF2 Bootloader state. Blinks fast when updating the firmware, and breathes slow when in idle state. |
| RGB LED - Red | P0.20 nRF52820 | Indicates the UART bridge state. Blinks fast when any UART bridge transmission is enabled, and stays off when in idle state. |
| RGB LED - Blue | P0.14 nRF52820 | Indicates the CMSIS-DAP state. Blinks fast when any DAP transmission is enabled, and stays off when in idle state. |
2.4 GHz antenna interface¶
The nRF54L15 Connect Kit has a U.FL receptacle for the external 2.4 GHz antenna. Included with the kit is a U.FL cabled 2.4 GHz antenna.
The following figure shows how to attach the U.FL cabled 2.4 GHz antenna:
NFC antenna interface¶
The nRF54L15 Connect Kit has a U.FL receptacle for the external NFC antenna. Included with the kit is a U.FL cabled 13.56MHz NFC antenna.
NFC uses pins NFC1 and NFC2 to connect the antenna. These pins are shared with GPIOs P1.02 and P1.03. The PROTECT field of the NFCPINS register in User Information Configuration Registers (UICR) defines the usage of these pins and their protection level against abnormal voltages. The content of the NFCPINS register is reloaded at every reset.
The following figure shows how to attach the U.FL cabled NFC antenna:
Debug interface¶
The nRF54L15 Connect Kit supports Arm Serial Wire Debug (SWD) port, which makes it possible to connect external debuggers for debugging and programming. Note that the signal voltage levels of SWD should match to VDD_GPIO.
The following figure illustrates the SWD port of the nRF54L15:
Connect the external debugger to nRF54L15
The SWD port of nRF54L15 is default connected to the Interface MCU's DAP interface. If an external debugger is wired to the SWD port of nRF54L15, the Interface MCU's DAP interface should be disabled.
The SWD port of Interface MCU (nRF52820) is also available for use. Note that the signal voltage levels of SWD should match to VDD_GPIO.
The following figure illustrates the SWD port of the Interface MCU (nRF52820):
Test points¶
The test points are exposed on the bottom of the board for debugging, testing, and validation purposes during development and production.
The following figure illustrates the test points:
The following table describes the functions of the test points:
| Test Point | Name | Description |
|---|---|---|
| TP1 | IF_USB_DP | USB D+ signal of the Interface MCU (nRF52820). |
| TP2 | IF_USB_DM | USB D- signal of the Interface MCU (nRF52820). |
| TP3 | IF_RESET | RESET pin of the Interface MCU (nRF52820). |
| TP4 | IF_SWCLK | Serial wire debug clock input of the Interface MCU (nRF52820). |
| TP5 | IF_SWDIO | Serial wire debug I/O of the Interface MCU (nRF52820). |