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4890AS–GPS–09/05

ATR0621 [Preliminary]

3.3.3

Serial I/O Configuration

The ATR0621 features a two-stage I/O message and protocol selection procedure for the two

available serial ports. At the first stage, a certain protocol can be enabled or disabled for a

given USART port. Selectable protocols are RTCM, NMEA and UBX. At the second stage,

messages can be enabled or disabled for each enabled protocol on each port. In all configura-

tions discussed below, all protocols are enabled on all ports. But output messages are

enabled in a way that ports appear to communicate at only one protocol. However, each port

will accept any input message in any of the three implemented protocols.

Both USART ports accept input messages in all three supported protocols (NMEA, RTCM and

UBX) at the configured baud rate. Input messages of all three protocols can be arbitrarily

mixed. Response to a query input message will always use the same protocol as the query

input message.

In Auto Mode, no output message is sent out by default, but all input messages are accepted

at any supported baud rate. Response to query input commands will be given the same proto-

col and baud rate as it was used for the query command. Using the respective configuration

commands, periodic output messages can be enabled.

The following message settings are used in Table 3-6:

Table 3-6.

Serial I/O Configuration

GPSMODE12

(Reset = PU)

GPSMODE6

(Reset = PU)

GPSMODE5

(Reset = PD)

USART1

(Output Protocol/

Baud Rate (kBaud))

USART2

(Output Protocol/

Baud Rate (kBaud)) Messages

Information Messages

0

0

0

UBX/57.6

NMEA/19.2

High

User, Notice, Warning, Error

0

0

1

UBX/38.4

NMEA/9.6

Medium

User, Notice, Warning, Error

0

1

0

UBX/19.2

NMEA/4.8

Low

User, Notice, Warning, Error

0

1

1

–/Auto

–/Auto

Off

None

1

0

0

NMEA/19.2

UBX/57.6

High

User, Notice, Warning, Error

1

0

1

NMEA/4.8

UBX/19.2

Low

User, Notice, Warning, Error

1

1

0

NMEA/9.6

UBX/38.4

Medium

User, Notice, Warning, Error

1

1

1

UBX/115.2

NMEA/19.2

Debug

All

Table 3-7.

Supported Messages at Setting Low

NMEA Port

Standard

GGA, RMC

UBX Port

NAV

SOL, SVINFO

Table 3-8.

Supported Messages at Setting Medium

NMEA Port

Standard

GGA, RMC, GSA, GSV, GLL, VTG, ZDA

UBX Port

NAV

SOL, SVINFO, POSECEF, POSLLH, STATUS, DOP, VELECEF,

VELNED, TIMEGPS, TIMEUTC, CLOCK