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NEO-M8L - Hardware integration manual
UBX-16010549 - R08
Hardware description
Page 6 of 28
C1-Public
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Avoid high resistance on the V_BCKP line: During the switch from main supply to backup supply,
a short current adjustment peak can cause high voltage drop on the pin with possible
malfunctions.
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If no backup supply voltage is available, connect the V_BCKP pin to VCC.
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As long as power is supplied to the NEO-M8L modules through the VCC pin, the backup battery is
disconnected from the RTC and the BBR to avoid unnecessary battery drain (see Figure 1). In this
case, VCC supplies power to the RTC and BBR.
Figure 1: Backup battery and voltage (for exact pin orientation, see the corresponding product Data sheet)
1.3.3
VDD_USB: USB interface power supply
VDD_USB supplies the USB interface. If the USB interface is not used, the VDD_USB pin must be
connected to GND. For more information about correctly handling the VDD_USB pin, see section 1.4.
1.3.4
VCC_RF: Output voltage RF
The VCC_RF pin can supply an active antenna or external LNA. For more information, see section 2.4.
1.4
Interfaces
For more information about the interfaces (baud rates, bandwidth, speed and clock frequency, and so
on), see the corresponding product data sheet [1], [2], or [3] in the Related documents section.
1.4.1
UART
NEO-M8L 3D dead reckoning modules include a Universal Asynchronous Receiver Transmitter
(UART) serial interface RXD/TXD supporting configurable baud rates.
The signal output and input levels are 0 V to VCC. An interface based on RS232 standard levels (+/-
12 V) can be implemented using level shifters such as Maxim MAX3232. Hardware handshake signals
and synchronous operation are not supported.
1.4.2
USB
A USB version 2.0 FS (full speed, 12 Mb/s) compatible interface is available for communication as an
alternative to the UART. The USB_DP integrates a pull-up resistor to signal a full-speed device to the
host. The VDD_USB pin supplies the USB interface.
u-blox provides Microsoft® certified USB drivers for Windows Vista, Windows 7, Windows 8 and
Windows 10. These drivers are available at our website,
USB external components
The USB interface requires some external components to implement the physical characteristics
required by the USB 2.0 specification. These external components are shown in Figure 2 and listed in
