UBX-G7020 - Hardware Integration Manual
Design-in
GPS.G7-HW-10003
Objective Specification
Page 21 of 74
2.2.4
Time pulse
There are 2 configurable time pulse output signals available with the UBX-G7020 chip; TIMEPULSE1 and
TIMEPULSE2. These two time pulse signals can only run on PIO11 and PIO12. By default only TIMEPULSE1 on
PIO11 is enabled and outputs a 1PPS signal.
The PIO12 is also used as the SAFEBOOT_N pin at start up, which is needed to enter the Safe Boot Mode, see
2.2.6.
For further information see
u-blox 7 Receiver description including protocol specification
2.2.5
External interrupt
There are 2 configurable external interrupt inputs available with the UBX-G7020 chip; EXTINT0 and EXTINT1
available at PIO13 and PIO14 respectively. By default both external interrupts, EXTINT0 and EXTINT1, are
disabled.
External Interrupts can be used for:
Wake-up in Power Save Mode.
For time mark aiding.
For frequency aiding.
For on/off control of the GPS/GNSS receiver
For further information see
u-blox 7 Receiver description including protocol specification
If the EXTINT pin is configured for on/off switching of the UBX-G7020 chip, the internal pull-up
becomes disabled. Thus make sure the EXTINT input is always driven within the defined voltage level by
the host.
2.2.6
SAFEBOOT_N Pin/ Safe Boot Mode
PIO12 is the SAFEBOOT_N pin. If this pin is “low” at start up, the UBX-G7020 will start up in Safe Boot Mode
and will not enter GPS/GNSS operation. In Safe Boot Mode the UBX-G7020 runs from an internal ring oscillator
and starts regardless of any configuration provided by the configuration pins or configuration saved in SQI flash.
Thus it can be used to recover from a situation where the SQI flash was corrupted or programmed with incorrect
Low Level Configuration settings.
Owing to the inaccurate frequency of the internal ring oscillator the UBX-G7020 is unable to communicate by
USB in Safe Boot Mode! For communication by UART in Safe Boot Mode a training sequence can be sent by the
host to the UBX-G7020 in order to enable communication. For further information see
u-blox 7 Receiver
description including protocol specification
[3]. The optional remapped UART interface is not available in Safe
Boot Mode.
Safe Boot Mode is used in production to program the SQI FLASH and to set the Low Level Configuration in the
eFuse or in the SQI flash.
It is recommended to have the possibility to pull the SAFEBOOT_N pin “low” at startup of the UBX-G7020. This
can be provided using an externally connected test point or via a host CPUs digital I/O port.
The UBX-G7020 is not able to communicate by USB in Safe Boot Mode.
All UBX-G7020 designs using SQI flash which do not use the default settings regarding oscillator, e.g.
26MHz crystal with 19pF load capacitance must be able to enter the Safe Boot Mode at production to
set the Low Level Configuration and program the SQI flash!
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