ZED-F9P-Integration Manual
UBX-18010802 - R02
4 Receiver description Page 34 of 114
Advance Information
The threshold should not be set above 2 kB, as the internal message buffer limit can be reached
before this, resulting in the TX-ready pin never being set as messages are discarded before the
threshold is reached.
4.5.2 Extended TX timeout
If the host does not communicate over SPI or DDC for more than approximately 2 seconds, the
device assumes that the host is no longer using this interface and no more packets are scheduled
for this port. This mechanism can be changed by enabling "extended TX timeouts", in which case
the receiver delays idling the port until the allocated and undelivered bytes for this port reach 4 kB.
This feature is especially useful when using the TX-ready feature with a message output rate of less
than once per second, and polling data only when data is available, determined by the TX-ready pin
becoming active.
4.5.3 UART Ports
One or two Universal Asynchronous Receiver/Transmitter (UART) ports are featured, that can be
used to transmit GNSS measurements, monitor status information and configure the receiver. See
our on-line product descriptions for availability.
The serial ports consist of an RX and a TX line. Neither handshaking signals nor hardware flow
control signals are available. These serial ports operate in asynchronous mode. The baud rates can
be configured individually for each serial port. However, there is no support for setting different baud
rates for reception and transmission.
As of Protocol version 18+, the UART RX interface will be disabled when more than 100 frame
errors are detected during a one-second period. This can happen if the wrong baud rate is used
or the UART RX pin is grounded. The error message appears when the UART RX interface is
re-enabled at the end of the one-second period.
Baud Rate Data Bits Parity Stop Bits
4800 8 none 1
9600 8 none 1
19200 8 none 1
38400 8 none 1
57600 8 none 1
115200 8 none 1
230400 8 none 1
460800 8 none 1
921600 8 none 1
Table 14: Possible UART Interface Configurations
Note that for protocols such as NMEA or UBX, it does not make sense to change the default word
length values (data bits) since these properties are defined by the protocol and not by the electrical
interface.
If the amount of data configured is too much for a certain port's bandwidth (e.g. all UBX messages
output on a UART port with a baud rate of 9600), the buffer will fill up. Once the buffer space is
exceeded, new messages to be sent will be dropped. To prevent message losses, the baud rate and
communication speed or the number of enabled messages should be selected so that the expected
number of bytes can be transmitted in less than one second.
4.5.4 USB Port
One Universal Serial Bus (USB) port is featured. See the Data Sheet of your specific product for
availability. This port can be used for communication purposes and to power the positioning chip
or module.
To Next Page
Loading...
Need help?
General
