NEO-D9S - Integration manual
3.1.6.1 Continuous mode
u-blox receivers use dedicated signal processing engines optimized for signal acquisition and
tracking. The acquisition engine delivers rapid signal searches during cold starts or when insufficient
signals are available for data download. The tracking engine delivers signal measurements for
message decoding.
3.1.6.2 Power on/off command - software back-up
With message UBX-RXM-PMREQ the receiver can be forced to enter
Inactive
state (software back-
up mode) with main power still applied. It will stay in
Inactive
state for the time specified in the
message or until it is woken up by activity on the RXD1, NRESET pin or EXTINT pin.
3.1.6.2.1 Wake up
The receiver can be woken up by generating an edge on one of the following pins:
• Rising or falling edge on one of the EXTINT pins
• Rising or falling edge on the RXD1 pin
• Rising edge on NRESET pin
All wake-up signals are interpreted as an acquisition request, where the receiver wakes up and tries
to obtain the satellite. Wake-up signals have no effect if the receiver is already in
Acquisition
,
Tracking
state.
3.1.6.2.2 Behavior while USB host connected
As long as the receiver is connected to a USB host, it will not enter the lowest possible power state.
This is because it must retain a small level of CPU activity to avoid breaching requirements of the
USB specification. The drawback, however, is that power consumption is higher.
Wake up by N_RESET, EXTINT pin or UART RX is possible even if the receiver is connected
to a USB host. In this case the state of the pin must be changed for a duration longer than
one millisecond.
3.2 Communication interfaces
u-blox receivers are equipped with a communication interface which is multi-protocol capable. The
interface ports can be used to transmit GNSS measurements, monitor status information and
configure the receiver.
A protocol (e.g. UBX, NMEA) can be assigned to several ports simultaneously, each configured with
individual settings (e.g. baud rate, message rates, etc.). More than one protocol (e.g. UBX protocol
and NMEA) can be assigned to a single port (multi-protocol capability), which is particularly useful
for debugging purposes.
The NEO-D9S provides UART1, UART2, SPI, I2C and USB interfaces for communication with a
host CPU. The interfaces are configured via the configuration methods described in the applicable
interface description [
].
It is important to isolate interface pins when VCC is removed. They can be allowed to float
or be connected to a high impedance (Float or tri-state: Hi-Z state). Open collector circuits
powered by module VCC are also suitable. They must be powered by module VCC to ensure
correct pin state when module VCC is removed.
Example isolation circuit is shown below.
UBX-19026111 - R07
3 Receiver functionality
Page 10 of 52
C1-Public
