The nRF5340 DK has multiple analog switches that are used to connect and disconnect signals based on different scenarios.
The USB and SW6 control the signal switches by using the USB_DETECT signal as an input to SW6. The interface MCU can be disconnected either by unplugging the USB cable from J2 or by toggling the nRF ONLY switch SW6.
The signal controls switches U3, U5, and U6 that break the connection between the nRF5340 SoC and the interface MCU and control the power for the interface MCU. For more information, see Interface MCU power.
Switches U3 and U5 break the connection of the Universal Asynchronous Receiver/Transmitter (UART) lines and Serial Wire Debug (SWD)/RESET lines. Depending on user preference, the signal controls the routing of the RESET signal when the interface MCU is connected or disconnected as follows:
- When the interface MCU is connected, shorting SB46 connects the RESET pin in the Arduino interface to the BOOT input of the interface MCU.
- Shorting SB43 connects the RESET pin in the Arduino interface to the RESET button.
When a shield is connected, two analog switches connect the pull-up resistors to the SDA and SCL I2C bus lines. This function uses one ground pin on the Arduino shield to control the switch. This feature can be disabled by cutting SB33. To permanently enable pull-up resistors, short SB32.