NINA-B1 series - System Integration Manual
UBX-15026175 - R06
System description
Page 12 of 48
1.6
Serial interfaces
As the NINA B1 module can be used with both the u-blox connectivity software and openCPU
based application, based on either the Nordic SDK or the ARM mbed platform, the available interfaces
and the pin mapping can differ. For detailed pin information see the Pin description section.
1.6.1
Universal Asynchronous Serial Interface (UART)
The NINA-B1 series module 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 4 wire UART with hardware flow control and 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-B1 module.
Depending on the bootloader used, the UART interface can also be used for firmware upgrade. See the Software
section for more information.
The u-blox connectivity 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-B1 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
See the
NINA-B1 series Data Sheet [2]
for characteristic information about the UART interface.
Interface
Default configuration
COM port
115200 baud, 8 data bits, no parity, 1 stop bit, hardware flow control
Table 4: Default settings for the COM port while using the u-blox connectivity Software
It is recommended to make the UART available either as test points or connected to a header for firmware
upgrade.
The IO level of the UART will follow the VCC voltage and it can thus be in the range of 1.8 V and 3.6 V. If you
are connecting the NINA-B1 module to a host with a different voltage on the UART interface, a level shifter
should be used.
1.6.2
Serial Peripheral Interface (SPI)
NINA-B1 supports up to 3 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 4 signals:
•
SCLK
•
MOSI
•
MISO
•
CS
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.
1.6.3
I
2
C interface
The Inter-Integrated Circuit (I
2
C) interfaces can be used to transfer or receive data on a 2-wire bus network. The
NINA-B1 modules can operate as both master and slave on the I
2
C bus using both standard (100 kbps) and fast
(400 kbps) transmission speeds. The interface uses the
SCL
signal to clock instructions and data on the
SDL
signal.
