LEA-M8F - Hardware Integration Manual
UBX-14000034 - R03
Early Production
Information
Hardware
description
Page 11 of 30
PIN
PIN 5 (D_SEL) = “high” (left open)
PIN 5 (D_SEL) = “Low” (connected to GND)
1
DDC SDA
SPI CS
2
DDC SCL
SPI CLK
3
UART TX
SPI MISO
4
UART RX
SPI MOSI
Table 3: D_SEL pin configuration
1.6.3
FREQ_PHASE_IN0 / EXINT0, FREQ_PHASE_IN1 / EXTINT1
These two frequency/phase inputs are provided for connecting an external source of phase (pulse stream) or
frequency reference into the module. The pulse stream can be derived from a frequency reference or external
synchronization source. The module will measure and report the phase or frequency offset of this input with
respect to the current synchronization source and optionally steer the related oscillator to bring the externally
derived pulses into alignment.
NB. These two pins have an alternate legacy function as external interrupts and are also called EXTINT0,EXTINT1
for compatibility with standard u-blox M8 functionality.
1.6.4
REF_FREQ_OUT
This pin carries a low phase noise buffered output from the module’s disciplined 30.72MHz VCTCXO (CMOS
buffer via on-module resistor).
1.6.5
TIMEPULSE / TP2
The timepulse signal is output from this pin. This pin is the standard u-blox M8 TP2 output, hence all timepulse
settings must be made with respect to TP2 in UBX control messages.
The timepulse output pin also functions as the SAFEBOOT_N input pin at start up, initiating a special Safe Boot
Mode operation from ROM if held LO during reset (for example for Flash firmware recovery). As a result,
applications using the timepulse output should ensure that this pin is not held LO during start-up in normal
operation. This can be achieved safely by re-buffering the timepulse output using the VDD_IO supply. This pin
has an internal pull-up resistor of nominally 11 k
Ω
.
1.7
Device Configuration
The device configuration can be modified using UBX protocol configuration messages. Configuration settings
for the FTS functionality are explored further in the accompanying Application Guide [3]. All modified settings
remain effective until power-down or reset. The configuration can be saved permanently in SQI flash using the
UBX-CFG-CFG
message. For a full explanation of all configuration messages, refer to the
u-blox M8 Receiver
Description Protocol Specification
