NINA-W1 series - System integration manual
UBX-17005730 - R11 System description Page 13 of 55
C1 - Public
In addition to UART support, NINA-W13 and NINA-W15 modules also include a Serial Peripheral
Interface (SPI) for data communication. The module acts as an SPI slave.
The following SPI signals are available:
• Chip select as input (SPI_CS)
• Data lines (SPI_MOSI as input, SPI_MISO as output)
• Clock (SPI_SCLK as input)
• Optional hardware flow control lines (SPI_NORX and SPI_DRDY as output)
For details on SPI operation, see the application note Communicating with a u-blox module over SPI
bus [10].
1.8 Antenna interfaces
Antenna interfaces are different for each module variant in the NINA-W1 series.
1.8.1 Antenna pin – NINA-W1x1
NINA-W1x1 modules are equipped with an RF pin. The pin has a nominal characteristic impedance of
50 Ω and must be connected to the antenna through a 50 Ω transmission line. This allows reception
of radio frequency (RF) signals in the 2.4 GHz frequency band.
Choose an antenna with optimal radiating characteristics for the best electrical performance and
overall module functionality. An internal antenna, integrated on the application board or an external
antenna connected to the application board through a proper 50 Ω connector, can be used.
When using an external antenna, the PCB-to-RF-cable transition must be implemented using either
a suitable 50 Ω connector, or an RF-signal solder pad (including GND) that is optimized for 50 Ω
characteristic impedance.
1.8.1.1 Antenna matching
The antenna return loss should be as good as possible across the entire band when the system is
operational to provide optimal performance. The enclosure, shields, other components, and
surrounding environment impacts the return loss that is seen at the antenna port. Matching
components are often required to retune the antenna and bring the return loss within an acceptable
range.
It is difficult to predict the actual matching values for the antenna in the final form factor. Therefore,
it is a good practice to have a placeholder in the circuit with a ”pi” network, with two shunt components
and a series component in the middle. This allows maximum flexibility while tuning the matching to
the antenna feed.
1.8.1.2 Approved antenna designs
NINA-W1 modules come with a pre-certified design that can be used to save costs and time during
the certification process. To take full advantage of this service, you must implement the antenna
layout in accordance with u-blox reference designs. Reference designs are available on request from
u-blox.
The designer integrating a u-blox reference design into an end-product is solely responsible for any
unintentional emission levels produced by the end product.
The module may be integrated with other antennas. In which case, the OEM installer must certify the
design with respective regulatory agencies.
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