3: Quick Start
GPS/GLONASS Receiver Module A5100-A User Guide
18
3.3 Serial Port Settings
In UART operation (defined by the external pull-up resistor as outlined in Minimum
Configuration) the default settings are:
•
NMEA, 9600 baud, 8 data bits, no parity, 1 stop bit, no flow control
3.3.1 Change Serial Port setting
This command message is used to set the protocol (SiRF binary or NMEA) and/or
the communication parameters (Baud rate, data bits, stop bits, and parity). The com-
mand is used to switch the module back to SiRF binary protocol mode where a more
extensive command message set is available. When a valid message is received,
the
parameters are stored in battery-backed SRAM and, after a reset, the receiver re-
sumes using the saved parameters.
Table 4 contains the input values for the following example:
Switch to Serial Port Band rate at 4800
Example: $PSRF100,1,4800,8,1,0*0E <CR><LF>
Name
Example
Description
MID
$PSRF100
PSRF100 Protocol header
Protocol
1
0 = SiRF binary
1 = NMEA
Baud
4800
1200, 2400, 4800, 9600, 19200, 38400, 57600, or
115200
DataBits
8
8 only
StopBits
1
1 only
Parity
0
0 = None only
Checksum *0E
-
<CR><LF> -
End of message termination
Table 4: Set Serial Port Data Format
3.4 Improved TTFF
In order to improve the TTFF (Time To First Fix), it is recommended to keep Vcc
supplied or backup battery at V_BAK at all times so that Navigation data and initial
condition (timing and approximate location) are kept current. To reduce power con-
sumption, customers can take advantage of the many sophisticated low power mode
features available in the SiRFstarV chipset.
