Integration Manual

NINA-B4 series - System integration manual
UBX-19052230 - R09 Design-in Page 17 of 60
C1-Public
2.4 Serial interfaces
⚠ As NINA B4 can be used with both the u-connectXpress and open CPU based applications based
on the Nordic SDK, the available interfaces and pin mapping vary. See also Pin configurations and
functions.
2.4.1 Universal Asynchronous Serial Interface (UART)
NINA B4 provides a Universal Asynchronous Serial Interface (UART) for data communication.
The following UART signals are available:
• Data lines (RXD as input, TXD as output)
• Hardware flow control lines (CTS as input, RTS as output)
• DSR and DTS are used to set and indicate system modes
The UART can be used as both a 4-wire UART with hardware flow control and a 2-wire UART with only
TXD and RXD. If using the UART in 2-wire mode, CTS should be connected to GND on the
NINA-B4 module.
Depending on the bootloader used, the UART interface can also be used for software upgrades. See
also Software options.
The u-connectXpress software adds the DSR and DTR pins to the UART interface. These pins are not
used as originally intended, but to control the state of the NINA-B4 module. Depending on the current
configuration, the DSR can be used to:
• Enter command mode
• Disconnect and/or toggle connectable status
• Enable/disable the rest of the UART interface
• Enter/wake up from the sleep mode
For more information about the characteristics of the UART interface, see also the respective data
sheets [2][3].
Interface
Default configuration
COM port
115200 baud, 8 data bits, no parity, 1 stop bit, hardware flow control
Table 10: Default settings for the COM port while using the u-connectXpress software
It is advisable to make the UART available either as test points or have them connected to a header
for a software upgrade. The I/O level of the UART follows the VCC voltage, which means that it can
consequently be in the range of 1.8 V and 3.6 V. Use a level shifter if you are connecting NINA-B4 to a
host with a different voltage on the UART interface.
2.4.2 Serial Peripheral Interface (SPI)
NINA-B40 (only) supports up to three serial peripheral interfaces that can operate in both master and
slave modes with a maximum serial clock frequency of 8 MHz in both these modes. The SPI interfaces
use the following signals:
• SCLK
• MOSI
• MISO
• CS
• DCX (Data/Command signal). This signal is optional but is sometimes used by the SPI slaves to
distinguish between SPI commands and data.
When using the SPI interface in master mode, it is possible to use GPIOs as additional Chip Select (CS)
signals to allow addressing of multiple slaves.