Hardware Description; Overview; Configuration; Connecting Power - u-blox NEO-M8U Hardware Integration Manual

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Hardware description

1.1 Overview

The NEO-M8U is an Untethered Dead Reckoning module bringing the benefits of dead reckoning to a
wider range of road-vehicle applications by eliminating the need for a speed or wheel-tick connection
to the vehicle. The module uses built-in gyroscope and accelerometer sensors and features the high
performance u-blox M8 concurrent positioning engine. Available in the NEO industry standard
leadless chip carrier (LCC) package, it is easy to integrate and combines 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.
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For more about product features see the
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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 Receiver Description Including Protocol Specification
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 there is no backup battery supply interrupt.
For NEO-M8U modules, the configuration can be saved permanently in SQI flash.

1.3 Connecting power

The NEO-M8U positioning module has up to three power supply pins: VCC, V_BCKP and VDD_USB.

1.3.1 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. For this reason, it is important that the supply circuitry be able to
support the peak power for a short time (see the
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When switching from backup mode to normal operation or at start-up, the NEO-M8U module must
charge the internal capacitors in the core domain. In certain situations, this can result in a
significant current draw. It is important that the power supply or low ESR capacitors at the module
input can deliver this current/charge.
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Use a proper GND concept. Do not use any resistors or coils in the power line.

1.3.2 V_BCKP: Backup supply voltage

If the module supply has a power failure, the V_BCKP pin supplies the real-time clock (RTC) and
battery backed RAM (BBR). 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.
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A backup supply voltage should be provided to the NEO-M8U to enable navigation by Dead
Reckoning before the first GNSS fix.
UBX-15016700 - R07
Production Information
NEO-M8U - Hardware Integration Manual
NEO-M8U Data Sheet
NEO-M8U Data Sheet
Hardware description
[1].
[2]). The modified settings remain
[1] for specification).
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