u-blox MAX-8, MAX-M8 User Manual
Abstract
This document describes the features and specifications of the u-blox MAX-8 / MAX-M8 module
series.
www.u-blox.com
UBX-15030059 - R06
MAX-8 / MAX-M8
u-blox 8 / M8 GNSS modules
Hardware integration manual
MAX-8 / MAX-M8 - Hardware integration manual
Title
MAX-8 / MAX-M8
Subtitle
u-blox 8 / M8 GNSS modules
Document type
Hardware integration manual
Document number
UBX-15030059
Revision and date
R06
27-May-2020
Document status
Production Information
Product status
Corresponding content status
In Development /
Prototype
Objective Specification
Target values. Revised and supplementary data will be published later.
Engineering Sample
Advance Information
Data based on early testing. Revised and supplementary data will be published later.
Initial Production
Early Production Information
Data from product verification. Revised and supplementary data may be published later.
Mass Production /
End of Life
Production Information
Document contains the final product specification.
European Union regulatory compliance
MAX-8 / MAX-M8 complies with all relevant requirements for RED 2014/53/EU. The MAX-8 / MAX-M8 Declaration of
Conformity (DoC) is available at www.u-blox.com within Support > Product resources > Conformity Declaration.
Product name
Type number
Firmware version
PCN reference
MAX-M8C
MAX-M8C-0-10
ROM SPG 3.01
UBX-16013125
MAX-M8W
MAX-M8W-0-10
ROM SPG 3.01
UBX-16013125
MAX-M8Q
MAX-M8Q-0-10
ROM SPG 3.01
UBX-16013125
MAX-8Q
MAX-8Q-0-10
ROM SPG 3.01
N/A
MAX-8C
MAX-8C-0-10
ROM SPG 3.01
N/A
u-blox or third parties may hold intellectual property rights in the products, names, logos and designs included in this
document. Copying, reproduction, modification or disclosure to third parties of this document or any part thereof is only
permitted with the express written permission of u-blox.
The information contained herein is provided “as is” and u-blox assumes no liability for its use. No warranty, either express or
implied, is given, including but not limited to, with respect to the accuracy, correctness, reliability and fitness for a particular
purpose of the information. This document may be revised by u-blox at any time without notice. For the most recent
documents, visit www.u-blox.com.
Copyright © u-blox AG.
Document information
This document applies to the following products:
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MAX-8 / MAX-M8 - Hardware integration manual
Contents
Document information ................................................................................................................................ 2
Contents .......................................................................................................................................................... 3
1 Hardware description ........................................................................................................................... 5
1.1 Overview ........................................................................................................................................................ 5
1.2 Configuration ............................................................................................................................................... 5
1.3 Connecting power ....................................................................................................................................... 5
1.3.1 VCC_IO: IO supply voltage ................................................................................................................. 6
1.3.2 V_BCKP: Backup supply voltage ...................................................................................................... 6
1.3.3 VCC_RF: Output voltage RF ............................................................................................................. 7
1.3.4 V_ANT: Antenna supply (MAX-M8W) ............................................................................................. 7
1.4 Interfaces ...................................................................................................................................................... 7
1.4.1 UART ..................................................................................................................................................... 7
1.4.2 Display data channel (DDC) .............................................................................................................. 7
1.4.3 TX_READY ............................................................................................................................................ 7
1.5 I/O pins ........................................................................................................................................................... 8
1.5.1 RESET_N: Reset input ....................................................................................................................... 8
1.5.2 EXTINT: External interrupt ............................................................................................................... 8
1.5.3 SAFEBOOT_N ...................................................................................................................................... 8
1.5.4 TIMEPULSE.......................................................................................................................................... 8
1.5.5 LNA_EN: LNA enable .......................................................................................................................... 8
1.5.6 ANT_DET: Open circuit detection (MAX-M8) ............................................................................... 9
1.6 Electromagnetic interference on I/O lines ............................................................................................. 9
2 Design ..................................................................................................................................................... 11
2.1 Pin description ...........................................................................................................................................11
2.1.1 Pin name changes.............................................................................................................................11
2.2 Minimal design...........................................................................................................................................12
2.3 Layout: Footprint and paste mask ........................................................................................................12
2.4 Antenna and antenna supervision ........................................................................................................13
2.4.1 Antenna design with passive antenna .........................................................................................13
2.4.2 Antenna design with active antenna ............................................................................................14
2.4.3 Antenna design with active antenna using antenna supervisor (MAX-M8W) ....................15
2.4.4 Status reporting ...............................................................................................................................16
2.4.5 Power and short detection antenna supervisor (MAX-M8W) .................................................16
2.4.6 Power, short and open detection antenna supervisor (MAX-M8W) ......................................18
2.5 Layout design-in: Thermal management .............................................................................................18
3 Migration to u-blox 8 / M8 modules .............................................................................................. 20
3.1 Migrating u-blox 7 designs to u-blox 8 / M8 modules ........................................................................20
3.2 Hardware migration from MAX-6 to MAX-8 / M8 ...............................................................................20
3.3 Software migration ...................................................................................................................................21
4 Product handling ................................................................................................................................. 22
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4.1 Packaging, shipping, storage and moisture preconditioning ..........................................................22
4.2 Soldering .....................................................................................................................................................22
4.3 EOS/ESD/EMI precautions ......................................................................................................................25
4.4 Applications with cellular modules ........................................................................................................28
Appendix ....................................................................................................................................................... 30
A Glossary ................................................................................................................................................. 30
B Recommended components ........................................................................................................... 30
Related documents ................................................................................................................................... 32
Revision history .......................................................................................................................................... 32
Contact .......................................................................................................................................................... 33
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MAX-8 / MAX-M8 - Hardware integration manual
eFuse
String
turn-off single-crystal feature
B5 62 06 41 09 00 01 01 92 81 E6 39 93 2B EE 30 31
1 Hardware description
1.1 Overview
u-blox MAX-8 / MAX-M8 modules are standard precision GNSS positioning modules featuring the
high-performance u-blox 8 / M8 positioning engine. Available in the industry standard MAX form
factor in a leadless chip carrier (LCC) package, 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 and place and reflow-soldering equipment for costefficient, high-volume production enabling short time-to-market.
☞ For product features see the data sheet for MAX-8 [1] or MAX-M8 [2] .
☞ 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 the ublox 8 / u-blox M8 Receiver Description including Protocol Specification [3]. The modified settings
remain effective until power-down or reset. If these settings have been stored in BBR (battery backed
RAM), the modified configuration will be retained as long as the backup battery supply (V_BCKP) is
not interrupted.
⚠ eFuse is one-time-programmable; it cannot be changed if it has been programmed once.
In order to save backup current, a u-blox MAX-8C / MAX-M8C module configured in “single crystal“
mode can have the single-crystal feature turned off by means of a SW command. Hot start
performance will be degraded (no time information at startup).
Use the string in Table 1 to turn off the single-crystal feature. This is recommended for low-power
applications, especially if time will be delivered by GSM or uC.
Table 1: String to turn off single-crystal feature
1.3 Connecting power
u-blox MAX-8 / MAX-M8 positioning modules have up to three power supply pins: VCC, VCC_IO, and
V_BCKP.
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
data sheet for MAX-8 [1] or MAX-M8 [2] for specification).
☞ When switching from backup mode to normal operation or at start-up, u-blox MAX-8 / MAX-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.
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1.3.1 VCC_IO: IO supply voltage
VCC_IO from the host system supplies the digital I/Os. The wide range of VCC_IO allows seamless
interfacing to standard logic voltage levels independent of the VCC voltage level. In many applications,
VCC_IO is simply connected to the main supply voltage.
☞ Without a VCC_IO supply, the system will remain in reset state.
1.3.2 V_BCKP: Backup supply voltage
If there is a power failure on the module supply (VCC_IO), the real-time clock (RTC) and battery backed
RAM (BBR) are supplied through the V_BCKP pin. Thus orbit information and time can be maintained
and will allow a hot or warm start. If no backup battery is connected, the module performs a cold start
at every power up if no aiding data are sent to the receiver
☞ 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_IO.
☞ As long as power is supplied to the u-blox 8 / M8 modules through the VCC_IO pin, the backup
battery is disconnected from the RTC and the BBR to avoid unnecessary battery drain (see Figure
1). In this case, VCC_IO supplies power to the RTC and BBR.
Figure 1: Backup battery and voltage (for exact pin orientation, see the data sheet for MAX-8 [1] or MAX-M8 [2] )
Single-crystal feature on MAX-8C / MAX-M8C
On MAX-8C / MAX-M8C, the reference frequency for the RTC clock will be internally derived from the
main clock frequency (26 MHz) when in backup mode (does not have a 32 kHz oscillator). This feature
is called “single-crystal” operation. In the event of a power failure, the backup battery at V_BCKP will
supply the 26 MHz crystal oscillator, as needed to maintain the time. This makes MAX-8C / MAX-M8C
a more cost-efficient solution at the expense of a higher backup current, as compared to other MAX8 / MAX-M8 variants that use an ordinary RTC crystal. Therefore, the capacity of the backup battery
at V_BCKP must be increased if hardware backup mode is needed (see the data sheet for MAX-8 [1]
or MAX-M8 [2] for specification).
If the battery used cannot provide the increased current consumption for the needed time on MAX8C / MAX-M8C, the “single-crystal” feature can be permanently disabled. The backup current will be
the same as on MAX-8 / MAX-M8 modules without the “single-crystal” feature. But the time
information is not maintained during off time. So the customer either aides the time to the receiver
at every startup, or the hot and warm start performance will be degraded because of missing time
information.
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Send this string to disable the “single-crystal” feature:
“B5 62 41 09 00 01 01 92 81 E6 39 93 2B EE 30 31”.
⚠ This string has to be sent once in production and will permanently turn off the single-crystal
feature on MAX-8C / MAX-M8C. The hot start and warm start performance will be degraded if time
information is not provided to the receiver at every startup.
1.3.3 VCC_RF: Output voltage RF
The VCC_RF pin can be used to supply an active antenna or an external LNA. For more information,
see section 2.4.
1.3.4 V_ANT: Antenna supply (MAX-M8W)
At V_ANT pin an antenna supply voltage can be connected which will be provided at RF_IN to supply
an active antenna. For more information see section 2.4.3.
☞ If not used, connect the V_ANT pin to GND.
1.4 Interfaces
1.4.1 UART
u-blox MAX-8 / MAX-M8 positioning modules include a Universal Asynchronous Receiver Transmitter
(UART) serial interface RXD/TXD that supports configurable baud rates. The UART output and input
levels are 0 V to VCC_IO. 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 Display data channel (DDC)
An I2C-compatible display data channel (DDC) interface is available with u-blox MAX-8 / MAX-M8
modules for serial communication with an external host CPU. The interface only supports operation
in slave mode (master mode is not supported). The DDC protocol and electrical interface are fully
compatible with the fast-mode of the I2C industry standard. DDC pins SDA and SCL have internal
pull-up resistors to VCC_IO.
For more information about the DDC implementation, see the u-blox 8 / u-blox M8 Receiver
Description including Protocol Specification [3]. For bandwidth information, see the MAX-8 Data
sheet [1] and MAX-M8 Data sheet [2]. For timing, parameters consult the I2C-bus specification [6].
☞ The u-blox MAX-8 / MAX-M8 DDC interface supports serial communication with u-blox cellular
modules. See the specification of the applicable cellular module to confirm compatibility.
1.4.3 TX_READY
The TX_READY function is used to indicate when the receiver has data to transmit. A listener can wait
on the TX_READY signal instead of polling the DDC or SPI interfaces. The UBX-CFG-PRT message lets
you configure the polarity and the number of bytes in the buffer before the TX READY signal goes
active. The TX_READY function can be mapped to TXD (PIO 06). The TX_READY function is disabled
by default.
☞ The TX_READY functionality can be enabled and configured by AT commands sent to the u-blox
cellular module supporting the feature. For more information, see the GPS Implementation and
Aiding Features in u-blox wireless modules [7].
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1.5 I/O pins
All I/O pins make use of internal pull-ups. Thus, there is no need to connect unused pins to VCC_IO.
1.5.1 RESET_N: Reset input
Driving RESET_N low activates a hardware reset of the system. Use this pin only to reset the module.
Do not use RESET_N to turn the module on and off, since the reset state increases power
consumption. In u-blox MAX-8 / MAX-M8 modules, RESET_N is an input only.
1.5.2 EXTINT: External interrupt
EXTINT is an external interrupt pin with fixed input voltage thresholds with respect to VCC_IO (see
the data sheet for MAX-8 [1] and MAX-M8 [2] for more information). It can be used for wake-up
functions in power save mode in all u-blox 8 / M8 modules and for aiding. Leave open if unused; the
functions are disabled by default.
If the EXTINT is not used for an external interrupt function, it can be used for some other purpose, for
example, as an output pin for the TX_READY feature to indicate that the receiver has data to
transmit.
Power control
The power control feature allows overriding the automatic active/inactive cycle of power save mode.
The state of the receiver can be controlled through the EXTINT pin. The receiver can also be forced
OFF using EXTINT when power save mode is not active.
Frequency aiding
The EXTINT pin can be used to supply time or frequency aiding data to the receiver.
For time aiding, hardware time synchronization can be achieved by connecting an accurate time pulse
to the EXTINT pin.
Frequency aiding can be implemented by connecting a periodic rectangular signal with a frequency up
to 500 kHz and an arbitrary duty cycle (low/high phase duration must not be shorter than 50 ns) to
the EXTINT pin. Provide the applied frequency value to the receiver using UBX messages.
1.5.3 SAFEBOOT_N
The SAFEBOOT_N pin is for future service, updates and reconfiguration.
1.5.4 TIMEPULSE
A configurable time pulse signal is available with all u-blox 8 / u-blox M8 modules. By default, the time
pulse signal is configured to 1 pulse per second. For more information, see the u-blox 8 / u-blox M8
Receiver Description including Protocol Specification [3].
1.5.5 LNA_EN: LNA enable
In the power save mode in MAX-M8Q, MAX-M8C, MAX-8C and MAX-8Q modules, the system can
turn on/off an optional external LNA using the LNA_EN signal to optimize power consumption.
Signals: "high" = Turn ON LNA, "low" = Turn OFF LNA
Antenna short circuit detection (ANT_OK) (MAX-M8W)
MAX-M8W module includes internal short circuit antenna detection. For more information, see
section 2.4.5.
"high" = Antenna is OK (e.g. no short)
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"low" = Antenna is not OK (e.g. short)
Antenna supervision is configurable using message UBX-CFG-ANT.
☞ Refer to the u-blox 8 / u-blox M8 Receiver Description including Protocol Specification [3] for
information about further settings.
1.5.6 ANT_DET: Open circuit detection (MAX-M8)
Antenna open circuit detection (ANT_DET) is not activated by default on the MAX-8 / MAX-M8
modules. ANT_DET can be mapped to PIO13 (EXTINT).
ANT_DET is an input used to report whether an external circuit has detected an external antenna or
not.
"high" = Antenna detected (antenna consumes current)
"low" = Antenna not detected (no current drawn)
Antenna supervision is configurable using message UBX-CFG-ANT.
☞ Refer to the u-blox 8 / u-blox M8 Receiver Description including Protocol Specification [3] for
information about further settings.
1.6 Electromagnetic interference on I/O lines
Any I/O signal line with a length greater than approximately 3 mm can act as an antenna and may pick
up arbitrary RF signals transferring them as noise into the GNSS receiver. This specifically applies to
unshielded lines, in which the corresponding GND layer is remote or missing entirely, and lines close
to the edges of the printed circuit board.
If, for example, a cellular signal radiates into an unshielded high-impedance line, it is possible to
generate noise in the order of volts and not only distort receiver operation but also damage it
permanently.
On the other hand, noise generated at the I/O pins will emit from unshielded I/O lines. Receiver
performance may be degraded when this noise is coupled into the GNSS antenna (see Figure 19).
To avoid interference by improperly shielded lines, it is recommended to use resistors (for example,
R>20 ), ferrite beads (for example, BLM15HD102SN1) or inductors (for example, LQG15HS47NJ02)
on the I/O lines in series. Choose these components with care because they also affect the signal rise
times.
Figure 2 shows an example of EMI protection measures on the RX/TX line using a ferrite bead. More
information can be found in section 4.3.
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Figure 2: EMI precautions
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