Motorola M12+ GPS Engine

Functions to control the Motorola M12+ GPS engine in native binary protocol mode. More...

Defines
#define	GPS_BUFFER_SIZE   50
	The maximum length of a binary GPS engine message.
Enumerations
enum	GPS_PARSE_STATE_MACHINE {   GPS_START1, GPS_START2, GPS_COMMAND1, GPS_COMMAND2,   GPS_READMESSAGE, GPS_CHECKSUMMESSAGE, GPS_EOMCR, GPS_EOMLF }
	GPS parse engine state machine values. More...
Functions
GPS_FIX_TYPE	gpsGetFixType ()
	Get the type of fix.
int32_t	gpsGetPeakAltitude ()
	Peak altitude detected while GPS is in 3D fix mode since the system was booted.
void	gpsInit ()
	Initialize the GPS subsystem.
bool_t	gpsIsReady ()
	Determine if new GPS message is ready to process.
uint8_t	gpsNMEAChecksum (uint8_t *buffer, uint8_t length)
	Calculate NMEA-0183 message checksum of buffer that is length bytes long.
bool_t	gpsSetup ()
	Verify the GPS engine is sending the @Hb position report message.
void	gpsParsePositionMessage ()
	Parse the Motorola @Hb (Short position/message) report.
void	gpsPowerOn ()
	Turn on the GPS engine power and serial interface.
void	gpsPowerOff ()
	Turn off the GPS engine power and serial interface.
void	gpsUpdate ()
	Read the serial FIFO and process complete GPS messages.
Variables
uint8_t	gpsIndex
	Index into gpsBuffer used to store message data.
GPS_PARSE_STATE_MACHINE	gpsParseState
	State machine used to parse the GPS message stream.
uint8_t	gpsBuffer [GPS_BUFFER_SIZE]
	Buffer to store data as it is read from the GPS engine.
int32_t	gpsPeakAltitude
	Peak altitude detected while GPS is in 3D fix mode.
uint8_t	gpsChecksum
	Checksum used to verify binary message from GPS engine.

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Detailed Description

Functions to control the Motorola M12+ GPS engine in native binary protocol mode.

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Define Documentation

#define GPS_BUFFER_SIZE   50

The maximum length of a binary GPS engine message.

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Enumeration Type Documentation

enum GPS_PARSE_STATE_MACHINE

GPS parse engine state machine values.

Enumerator:

GPS_START1	1st start character '@'
GPS_START2	2nd start character '@'
GPS_COMMAND1	Upper case 'A' - 'Z' message type.
GPS_COMMAND2	Lower case 'a' - 'z' message type.
GPS_READMESSAGE	0 - xx bytes based on message type 'Aa'
GPS_CHECKSUMMESSAGE	8-bit checksum
GPS_EOMCR	End of message - Carriage Return.
GPS_EOMLF	End of message - Line Feed.

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Function Documentation

GPS_FIX_TYPE gpsGetFixType

(

)

Get the type of fix.

Returns:

gps fix type enumeration

References GPS_2D_FIX, GPS_3D_FIX, GPS_NO_FIX, and gpsPosition.

Referenced by ballastCheck(), cutDownCheck(), gpsParsePositionMessage(), main(), tncGPGGAPacket(), tncGPRMCPacket(), and tncStatusPacket().

int32_t gpsGetPeakAltitude

(

)

Peak altitude detected while GPS is in 3D fix mode since the system was booted.

Returns:

altitude in feet

References gpsPeakAltitude.

void gpsInit

(

)

Initialize the GPS subsystem.

References GPS_START1, gpsParseState, gpsPeakAltitude, and gpsPosition.

Referenced by main().

bool_t gpsIsReady

(

)

Determine if new GPS message is ready to process.

This function is a one shot and typically returns true once a second for each GPS position fix.

Returns:

true if new message available; otherwise false

References gpsPosition.

Referenced by gpsSetup(), and main().

uint8_t gpsNMEAChecksum	(	uint8_t *	buffer,
		uint8_t	length
	)

Calculate NMEA-0183 message checksum of buffer that is length bytes long.

Parameters:

	buffer	pointer to data buffer.
	length	number of bytes in buffer.

Returns:

checksum of buffer

Referenced by tncGPGGAPacket(), and tncGPRMCPacket().

void gpsParsePositionMessage

(

)

Parse the Motorola @Hb (Short position/message) report.

References GPS_3D_FIX, gpsBuffer, gpsGetFixType(), gpsPeakAltitude, and gpsPosition.

Referenced by gpsUpdate().

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void gpsPowerOff

(

)

Turn off the GPS engine power and serial interface.

References IO_GPS_PWR.

Referenced by diagPort().

void gpsPowerOn

(

)

Turn on the GPS engine power and serial interface.

References IO_GPS_PWR.

Referenced by diagPort().

bool_t gpsSetup

(

)

Verify the GPS engine is sending the @Hb position report message.

If not, configure the GPS engine to send the desired report.

Returns:

true if GPS engine operation; otherwise false

References gpsIsReady(), gpsUpdate(), TIME_DUTYCYCLE_20, timeGetTicks(), and timeSetDutyCycle().

Referenced by main().

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void gpsUpdate

(

)

Read the serial FIFO and process complete GPS messages.

References GPS_CHECKSUMMESSAGE, GPS_COMMAND1, GPS_COMMAND2, GPS_EOMCR, GPS_EOMLF, GPS_READMESSAGE, GPS_START1, GPS_START2, gpsBuffer, gpsChecksum, gpsIndex, gpsParsePositionMessage(), gpsParseState, serialHasData(), and serialRead().

Referenced by gpsSetup(), and main().

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Variable Documentation

uint8_t gpsBuffer[GPS_BUFFER_SIZE]

Buffer to store data as it is read from the GPS engine.

Referenced by gpsParsePositionMessage(), and gpsUpdate().

uint8_t gpsChecksum

Checksum used to verify binary message from GPS engine.

Referenced by gpsUpdate().

uint8_t gpsIndex

Index into gpsBuffer used to store message data.

Referenced by gpsUpdate().

GPS_PARSE_STATE_MACHINE gpsParseState

State machine used to parse the GPS message stream.

Referenced by gpsInit(), and gpsUpdate().

int32_t gpsPeakAltitude

Peak altitude detected while GPS is in 3D fix mode.

Referenced by gpsGetPeakAltitude(), gpsInit(), and gpsParsePositionMessage().