NEO-M8 - Hardware Integration Manual
Hardware description
UBX-13003557 - R01 Objective Specification Page 4 of 26
1 Hardware description
1.1 Overview
u-blox M8 modules are standalone GNSS positioning modules featuring the high performance u-blox M8
positioning engine. Available in industry standard form factors in leadless chip carrier (LCC) packages, they are
easy to integrate and combine exceptional positioning performance with highly flexible power, design, and
connectivity options. SMT pads allow fully automated assembly with standard pick & place and reflow-soldering
equipment for cost-efficient, high-volume production enabling short time-to-market.
For product features see the NEO-M8 Data Sheet [1].
To determine which u-blox product best meets your needs, see the product selector tables on the u-blox
website www.u-blox.com.
1.2 Configuration
The configuration settings can be modified using UBX protocol configuration messages, see u-blox M8-V15
Receiver Description Protocol Spec [2]. The modified settings remain effective until power-down or reset. If
these settings have been stored in BBR (Battery Backed RAM), then the modified configuration will be retained,
as long as the backup battery supply is not interrupted.
For NEO-M8N module, configuration can be saved permanently in SQI flash.
1.3 Connecting power
u-blox M8 positioning modules have up to three power supply pins: VCC, V_BCKP and VDD_USB.
VCC: Main supply voltage
The VCC pin provides the main supply voltage. During operation, the current drawn by the module can vary by
some orders of magnitude, especially if enabling low-power operation modes. For this reason, it is important
that the supply circuitry be able to support the peak power for a short time (see the NEO-M8 Data Sheet [1] for
specification).
When switching from backup mode (see section 1.3.2) to normal operation or at start-up, u-blox M8
modules must charge the internal capacitors in the core domain. In certain situations, this can result in a
significant current draw. For low power applications using Power Save and backup modes it is important
that the power supply or low ESR capacitors at the module input can deliver this current/charge.
Use a proper GND concept. Do not use any resistors or coils in the power line.
V_BCKP: Backup supply voltage
If there is a power failure on the module supply, the real-time clock (RTC) and battery backed RAM (BBR) are
supplied through the V_BCKP pin. Use of valid time and the GNSS orbit data at start up will improve the GNSS
performance, as with hot starts, warm starts, AssistNow Autonomous and AssistNow Offline. If no backup
battery is connected, the module performs a cold start at power up.
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.
If no backup supply voltage is available, connect the V_BCKP pin to VCC.
As long as power is supplied to the u-blox M8 module 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.
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