u-blox EVK-NINA-B3 Series, User Manual

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EVK-NINA-B3 - User Guide
UBX-17056481 - R03 Product description Page 17 of 31
Conn. Pin
No. Raspberry
Pi pin Description Schematic
net name nRF52
pin Alternate functions and notes
32 GPIO12 Digital I/O GPIO_38 P1.10
33 GPIO13 Digital I/O GPIO_37 P1.03
34 GND Ground GND GND
35 GPIO19 Digital I/O GPIO_36 P1.02
36 GPIO16 Digital I/O GPIO_35 P1.01
37 GPIO26 Digital I/O GPIO_34 P1.08
38 GPIO20 Digital I/O GPIO_33 P1.09
39 GND Ground GND GND
40 GPIO21 Digital I/O GPIO_32 P0.11
Table 10: Pinout of the Raspberry Pi compatible interface
1.8.1 Powering considerations
There are two voltage nets used in the Raspberry Pi interface - 3V3_PI and 5V. Both the 3V3_PI and
5V nets can be used to power HATs, but should not be used when connecting to a Raspberry Pi. See
section 1.6.6 for more information.
⚠
The 3V3_PI power net must not be connected to the 3.3 V supply when connected to a Raspberry
Pi board. It could damage both the boards.
1.8.2 UART
The Raspberry Pi interface provides two pins that can be used for UART communications GPIO14 and
GPIO15 . In UART communications, signals are always connected RX <-> TX and vice versa. This means
that on a Raspberry Pi board GPIO14 will be TX and on a HAT it will be RX. To support talking to both
HATs and Pi boards, the zero
Ω
resistors - R57, R58, R59 and R60 can be used to toggle the NINA TX
and RX pins between GPIO14 and GPIO15 . If a NINA-B30 is used, this switch can also be made in the
software. By default, the EVK-NINA-B3 will be configured to simulate a HAT, and GPIO14 is connected
to the NINA UART_RXD pin and GPIO15 is connected to the NINA UART_TXD pin.
1.8.3 EEPROM support
The Raspberry Pi interface supports a unique EEPROM solution to store the HAT specific GPIO
configurations on the HAT board, to be read by the Raspberry Pi before configuring its GPIOs. The two
pins used for this -
ID_SD and ID_SC , are connected to the NINA-B3 module. The NINA module can
thus either read the GPIO configuration from a HAT, or simulate an EEPROM and send configurations
to a connected Pi. This requires a NINA-B30 module and a custom built application.
It is not mandatory to use this EEPROM solution; if not used, the two NINA pins GPIO_42 and GPIO_41
can be left unconfigured.
Two pull-up resistors - R44 and R50, can be added to the I
2
C lines if needed. They are not mounted on
the evaluation board by default.
Visit https://github.com/raspberrypi/hats/blob/master/designguide.md for more information on the
ID EEPROM specification.