u-blox EVK-NINA-B50, Руководство пользователя

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EVK-NINA-B50 - User guide
UBX-23007761 - R02 Interfaces and peripherals Page 29 of 37
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Extra memory – external Flash
NINA-B50 series modules can accommodate extra memory outside of the module. The memory space
can be used to store data and/or expand the application code size.
NINA-B50 modules support an SPI (Serial Peripheral Interface) to communicate with the external
flash memory. For information about the supported modes, clock frequencies and other features of
the SPI, see the NINA-B50 series data sheet
[1] .
SPI signals are shared with other interfaces and GPIO functions and are routed to the GPIO pin header
J14 (Raspberry Pi interface) and flash memory footprint on the bottom side of the evaluation board.
To reduce the risk of interference on the SPI, solder bridges have been added to the signal lines. Before
soldering the flash memory to the board, the solder bridges must be cut to isolate the copper traces
routed to J14.
Figure 19 shows where to cut the bridges.
Figure 19: Cut these solder bridges before soldering the external memory
The board outline is designed with a footprint for SOIC-8 packages with 5.3 mm body width. The
smaller footprint above this can accommodate a 0402 sized ~100 nF decoupling capacitor, which is
recommended to stabilize the memory supply.
Extra USB to UART interface
If the evaluation board is connected to a PC using the USB connector J8, two serial COM ports are
available. The COM port labeled
“ JLink CDC UART” (on a Windows PC) is not normally connected to
anything. It is instead routed as a 4-pin UART interface to the pin header J20. This interface could be
connected to a secondary UART interface on the NINA-B50 module, or to a UART interface on an
Arduino shield for example.
CPU trace interface
The Arm Cortex-M33 processor in NINA-B50 modules supports tracing of CPU instructions through
the 20-pin, 50 mil pitch, Cortex Debug + ETM connector. This extended connector has the same
features as J12, but also accommodates instruction trace operations through the Embedded Trace
Macrocell (ETM) of the Cortex-M33 microcontroller in the NINA-B50 module. Tracing instructions
through this connector requires a special external debugger.
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Note that the 50 mil pitch pin header is not soldered onto the evaluation board by default.