Integration Manual

ANNA-B4 series - System integration manual
UBX-21000517 - R03 Contents Page 19 of 76
C1-Public
ANNA-B4 modules have been tested with a 3 x 3 cm PCB trace antenna, so it is advisable to keep these
measurements as closely as possible to antenna design. You can still use a smaller or larger antenna
if it is tuned to resonate at 13.56 MHz. To comply with European regulatory demands, the NFC
antenna must be placed in such a way that the space between the ANNA-B4 module and the remote
NFC transmitter is always within three meters during transmission.
Battery protection
If the antenna is exposed to a strong NFC field, parasitic diodes and unintended ESD structures can
cause the current to flow in the opposite direction of the supply.
If the battery used does not tolerate a return current, protect the battery with a series diode placed
between the battery and the device.
2.9 Debug interface
ANNA-B402 modules support Serial Wire debug (SWD) and Serial Wire Viewer, but not JTAG debug.
When designing your application with the ANNA-B402, the SWD interface (pins SWDCLK and
SWDIO) to the module should ideally be made available in the application design.
So that ANNA-B402 can be flashed over the UART or SWD interface, the module is preloaded with
bootloader software that is without security. A debug connector to the module is also useful during
the software development.
For security reasons, the debug interface should be disabled to prevent the upload or download of
insecure software – or software that has not been validated.
Figure 6 shows the pinout of the 10-pin, 50 mil pitch connector used on the EVK-ANNA-B402. This
compact debug header can also be used on a host board design. Keep in mind that the GND and
VDD_IO references are needed for the SWD interface to work.
Figure 6: Cortex debug connector pin out for SWD
Thermal guidelines
ANNA-B4 series modules have been successfully tested from –40 °C to +105 °C. ANNA-B4 modules
are low-power devices that generate only a small amount of heat during operation. A good grounding
should nonetheless be observed for temperature relief during high ambient temperatures.
2.10 Reserved pins (RSVD)
Do not connect any reserved (RSVD) pins. The reserved pins can be allocated for future interfaces and
functionality.