u-blox UBX-G7020, Руководство по интеграции оборудования, Страница: 20 / 74

UBX-G7020 - Hardware Integration Manual
Design-in
GPS.G7-HW-10003 Objective Specification Page 20 of 74
2.2.3.2 Display Data Channel (DDC) Interface
An I
2
C compatible Display Data Channel (DDC) interface is available for serial communication with a host CPU.
The PIO8 (SCL) and PIO9 (SDA) pins have internal pull-up resistors sufficient for most applications. However,
depends on the speed of the host and the load on the DDC lines it might happen that additional external pull-up
resistors are necessary.
To make use of DDC interface the PIO10 (D_SEL) has to be left open.
The UBX-G7020 DDC interface provides serial communication with u-blox LEON-G100/G200 wireless
modules from version LEON-G100/G200-05S and above and on all LISA modules.
The TX-ready feature is supported on version LEON FW 7.xx and LISA-U2 01S and above.
For more information about DDC implementation refer to the u-blox 7 Receiver Description including Protocol
Specification [3].
2.2.3.3 SPI Interface
The SPI port provides a serial communication interface with a host CPU.
To make use of the SPI interface, PIO10 (D_SEL) has to be connected to GND.
2.2.3.4 Electromagnetic interference on interface signal lines
Any interface signal line (length > ~3 mm) may pick up high frequency signals and transfer this noise into the
GPS/GNSS receiver. This specifically applies to unshielded lines, lines were the corresponding GND layer is remote
or missing entirely, and lines close to the edges of the printed circuit board. If a GSM signal radiates into an
unshielded high-impedance line, noise in the order of Volts can be generated and eventually not only distort
receiver operation but also damage it permanently.
In such case it is recommended to use feed-thru capacitors with a good GND connection close to the GPS/GNSS
receiver in order to filter such high-frequency noise. See Section 3.19 for component recommendations.
Alternatively, ferrite beads (see Section 3.18) can be used. These work without GND connection but may
adversely affect signal rise time.
EMI protection measures are recommended when RF emitting devices are near the GPS/GNSS receiver. To
minimize the effect of EMI a robust grounding concept is essential. To achieve electromagnetic robustness follow
the standard EMI suppression techniques. Some references are provided in [4] and [5].
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