LEA-M8F - Hardware Integration Manual
UBX-14000034 - R03
Early Production
Information
Hardware
description
Page 7 of 30
1.3
Pin description for LEA-M8F designs
Function
PIN
No
I/O Description
Remarks
Power
VCC
6
I
Supply Voltage
Provide a clean and stable supply.
GND
7,
13-
15,
17
I
Ground
Assure a low impedance
GND
connection to all
GND
pins of
the module, preferably with a large ground.
V_BCKP
11
I
connect to
VCC
. (Back-up mode not supported)
VDDUSB
24
I
USB Power Supply
To use the USB interface connect this pin to 3.0 – 3.6 V
derived from VBUS.
If no USB serial port used connect to GND.
Antenna
RF_INPUT
16
I
GPS/GLONASS/
BeiDou/signal input
from antenna
Use a controlled impedance transmission line of 50
Ω
to
connect to RF_IN.
Don’t supply DC through this pin. Use
V_ANT
pin to supply
power.
VCC_RF
18
O
Output Voltage RF
section
Can be used to power an external active antenna
Ω
). The max
power consumption of the Antenna must not exceed the
datasheet specification of the module.
Leave open if not used.
V_ANT
19
I
Antenna Bias voltage Connect to
GND
(or leave open) if Passive Antenna is used. If
an active Antenna is used, add a 10
Ω
resistor in front of
V_ANT
input to the Antenna Bias Voltage or
VCC_RF
Reserved
20
I
Leave open
UART
TxD1/MISO/
TX ready
3
O
Serial Port 1 or SPI
Data i/p
Communication interface o/p function dependent on D_SEL. It
can also can be programmed as TX ready for DDC interface.
Leave open if not used.
RxD1/MOSI
4
I
Serial Port 1 or SPI
Data o/p
Communication interface i/p dependent on D_SEL with
internal pull-up resistor to VCC. Leave open if not used. Don’t
use external pull up resistor.
USB
USB_DM
25
I/O
USB I/O line
USB2.0 bidirectional communication pin. Leave open if
unused. For example implementations see
section 1.5.2
USB_DP
26
I/O
USB I/O line
System
RESET_N
10
I
Hardware Reset
(Active Low)
Leave open if not used.
TIMEPULSE/TP2/
SAFEBOOT_N
28
I/O
Timepulse Signal
Configurable Timepulse signal (one pulse per second by
default). Leave open if not used.
FREQ_PHASE_IN0/
EXTINT0
27
I
TimePulse/Frequency
General purpose frequency/phase measurement input 0,
Alternate function: External Interrupt 0
FREQ_PHASE_IN1/
EXTINT1
21
I
TimePulse/Frequency
General purpose frequency/phase measurement input 1
Alternate function: External Interrupt 1
REF_FREQ_OUT
9
I
VCTCXO o/p
Buffered output from the disciplined internal 30.72MHz
VCTCXO
SDA
/CS_N
1
I/O
DDC Data Pin
or SPI chip sel.
DDC Data. Leave open if not used.
or SPI chip select: dependent on DSEL
SCL
/SCLK
2
I/O
DDC Clk Pin
or SPI clk
DDC Clock. Leave open if not used.
or SPI clock: dependent on DSEL
SAFEBOOT_N
12
I
Test-point for service access. Leave open, do not drive low.
D_SEL
5
Selects the
interface protocol
Used to select UART+DDC or SPI
Open = UART+DDC; low = SPI on pins 1,2,3,4
SDA_DAC
22
I/O
DDC Data pin
For DAC control of external Freq Reference Only
SCL_DAC
23
O
DDC Clk pin
For DAC control of external Freq Reference Only
Table 1: LEA-M8F Pinout
