u-blox NEO-D9C, Integration Manual

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NEO-D9C - Integration manual
message content in any way. The only processing done on the raw subframe-level data is error
detection and correction, according to the receiver’s configuration.
There are three possible modes of operation:
1. No error detection or correction. The data is sent out as is, framed at the QZSS L6 250-byte
boundary.
2. Error detection only. The data is sent out as is, but the frame is accompanied by a meta-data
header indicating whether or not the message passed to the Reed-Solomon error detection.
3. Error detection and correction.
The received complete subframes are passed to Reed-
Solomon error correction. If the data contains any errors, either preamble or payload,
error recovery is attempted. If the error correction results in a frame that passes the error
detection, the corrected frame is sent out accompanied with a meta-data header indicating
how many bytes were corrected. This includes the preamble bytes. Hence, the maximum
number of correctable errors is 20 (up to 4 errors in the preamble and up to 16 in the payload
in the Reed-Solomon). If the error correction fails, the received data is sent out as is (without
applying any correction attempts, including the preamble) and the frame is marked as
erroneous.
The NEO-D9C will output the raw QZSS L6 data messages in the UBX-RXM-QZSSL6 message. This
message can contain both the L6D and L6E service data if required.
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-D9C 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 [
2 ].
The following table shows the port numbers reported in the UBX-MON-COMMS messages.
Port no. UBX-MON-COMMS portId Electrical interface
0 0x0000 I2C
1 0x0100 UART1
2 0x0200 UART2
3 0x0300 USB
4 0x0400 SPI
Table 2: Port number assignment
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-21031631 - R02 3 Receiver functionality Page 14 of 53
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