Integration Manual

NINA-B4 series - System integration manual
UBX-19052230 - R09 Open CPU software Page 40 of 60
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3.2.2.4 Hardware prerequisites for using the boot loader
To use the pre flashed boot loader the HW pins for UART and SWITCH_2 need to be mapped according
to Table 18. This is the same pin mapping used by the u-connectXpress software.
Signal
Pin mapping (nRF pin nr)
UART_RX
IO_23 (P0.29)
UART_TX
IO_22 (P1.05)
UART_CTS (optional)
IO_21 (P0.23)
UART_RTS (optional)
IO_20 (P0.31)
SWITCH_2
IO_18 (P0.02)
Table 18 Pin mapping used by boot loader
The UART_CTS and UART_RTS (flow control signals) are optional, but u-blox recommend using flow
control over the UART.