NINA-B2 series - System integration manual
UBX-18011096 - R05
Design-in
Page 23 of 35
C1- Public
On-board antenna design (NINA-B222)
Keep a minimum clearance of 5 mm between the antenna and the casing. Keep a minimum of 10 mm
free space from the metal around the antenna including the area below the antenna. If a metal
enclosure is required, NINA-B221 with antenna pin must be used.
It is recommended to place the NINA-B222 module so that the internal antenna is in the corner of the
host PCB (Pin 15/16 should be in the corner) as shown in Figure 7. The antenna side (short side closest
to the antenna), positioned along one side of the host PCB ground plane is the second-best option. It
is beneficial to have a large ground plane on the host PCB and have a good grounding on the NINA-B2
module.
Figure 7: NINA-B222 with internal antenna
⚠
Take care while handling the EVK-NINA-B222. Applying force to the module might damage the
internal antenna.
3.4
Data communication interfaces
Asynchronous serial interface (UART) design
The layout of the UART bus should be done so that noise injection and cross talk are avoided. It is
recommended to use the hardware flow control with RTS/CTS to prevent temporary UART buffer
overrun.
The
RTS/CTS
flow control signals are active low, which means that a 0 (ON state =low level) allows
the UART to transmit.
•
CTS
is an input to the NINA-B2 module. If the host sets this signal to 0 (ON state = low level) the
module is allowed to transmit.
•
RTS
is an output signal from the NINA-B2 module. The module sets this signal to a 0 (ON state =
low level) when it is ready to receive transmission.
3.5
General High Speed layout guidelines
These general design guidelines are considered as best practices and are valid for any bus present in
the NINA-B2 series modules; the designer should prioritize the layout of higher speed busses. Low
frequency signals are generally not critical for layout.
☞
One exception is represented by High Impedance traces (such as signals driven by weak pull
resistors) that may be affected by crosstalk. For those traces, a supplementary isolation of 4w
from other busses is recommended.
