ZOE-M8 series - Hardware integration manual
UBX-16030136 - R09
Design-in
Page 14 of 34
Production information
2.6
Safe boot mode (SAFEBOOT_N)
If the SAFEBOOT_N pin is “low” at startup, the ZOE-M8 GNSS SiPs start in safe boot mode and does
not begin GNSS operation. In safe boot mode, the SiP runs from an internal LC oscillator and starts
regardless of any configuration provided by the configuration pins. Thus, it can be used to recover
from situations where the SQI flash has become corrupted.
For communication by UART in safe boot mode, a training sequence (0x 55 55 at 9600 baud) can be
sent by the host to the ZOE-M8 GNSS SiPs in order to enable communication. After sending the
training sequence, the host must wait for at least 2 ms before sending messages to the receiver. For
further information, see the u-blox 8 / u-blox M8 Receiver Description including Protocol Specification
[2].
Safe boot mode is used in production to program the SQI flash. It is recommended to have the
possibility to pull the SAFEBOOT_N pin “low” when the SiP starts up. This can be provided using an
externally connected test point or via a host CPUs digital I/O port.
2.7
System reset (RESET_N)
The ZOE-M8 GNSS SiPs provide a RESET_N pin to reset the system. The RESET_N is input-only with
internal pull-up resistor. It must be at low level for at least 10 ms to make sure RESET_N is detected.
Leave RESET_N open for normal operation. The RESET_N complies with the VCC level and can be
actively driven high.
☞
Use RESET_N in critical situations only to recover the system. The real-time clock (RTC) will also
be reset and thus immediately afterwards the receiver cannot perform a hot start.
☞
In reset state, the SiP consumes a significant amount of current. It is therefore recommended to
use RESET_N only as a reset signal and not as an enable/disable.
2.8
Pin description
Pin # SiP
Name
I/O Description
Remark
A1
All
GND
Ground
Ensure good GND connection
A2
All
SDA / SPI CS_N I/O Serial interface.
See section 2.2
A3
All
GND
Ground
Ensure good GND connection
A4
All
RF_IN
I
GNSS signal input
See section 2.5
A5
All
GND
Ground
Ensure good GND connection
A6
All
Reserved
I/O Reserved. Do not connect.
Must be left open!
A7
All
GND
Ground
Ensure good GND connection
A8
All
GND
Ground
Ensure good GND connection
A9
All
GND
Ground
Ensure good GND connection
B1
All
SCL / SPI CLK
I
Serial interface.
See section 2.2
B9
All
GND
Ground
Ensure good GND connection
C1
All
SQI_D1
I
Data line 1 to external SQI flash memory
or DC/DC configuration pin.
Leave open if not used.
C3
All
TIMEPLUSE
O
Time pulse output
Leave open if not used.
C4
All
SAFEBOOT_N
I
Used for programming the SQI flash
memory and testing purposes.
Leave open if not used.
C5
All
LNA_EN
O
LNA on/off signal connected to internal
LNA
Leave open if not used.
C6
All
PIO15
I/O Digital I/O
Leave open if not used.
C7
All
GND
Ground
Ensure good GND connection
