Ublox EVK-NORA-B1, User Manual

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EVK-NORA-B1 - User guide
UBX-20030319 - R06 Hardware description Page 12 of 31
C1-Public
Figure 6: UART level shifters and disable switches
☞
Figure 6 reflects Rev D and Rev E hardware versions.
☞
For Rev C or earlier hardware versions, applications need to map the following VCOM0 handshake
signals:
o
VCOM0_RTS = P0.12
o
VCOM0_CTS = P0.10
o
VCOM0_TxD = P1.00 (no change)
o
VCOM0_RxD = P1.01 (no change)
2.6 32.768 kHz low frequency clock
The low frequency (LF) clock of the NORA-B1 module can have one of four sources:
•
Internal ultra-low power RC oscillator – for low-precision timing where low power is the main
requirement
• Internal calibrated RC oscillator – for applications with no strict real-time requirements
• Internal synthesized clock – derived from the 32 MHz clock
•
External crystal oscillator – offers the most accurate and lowest power LF clock
The evaluation board has a 32.768 kHz crystal connected to the NORA-B1 module to allow use of the
external crystal oscillator option. Loading capacitors for the oscillator circuit are internal to the nRF53
within the module. Values of 6 pF, 7 pF, and 11 pF can be enabled through register XOSC32KI.INTCAP.