TNC (Terminal Node Controller)

Functions that provide a subset of the TNC functions. More...

Defines

#define TNC_TX_DELAY   45

The number of start flag bytes to send before the packet message. (300mS).

#define TNC_TIMESLOT   55

The UTC time in seconds to send an APRS packet.

#define TNC_BUFFER_SIZE   80

#define TNC_DWELL_TIME   3600

Enumerations

enum TNC_MODE {
  TNC_TX_READY, TNC_TX_SYNC, TNC_TX_HEADER, TNC_TX_DATA,
  TNC_TX_END
}

TNC state machine. More...

Functions

void tncInit ()

bool_t tncIsFree ()

Determine if the hardware if ready to transmit a 1200 baud packet.

void tncTimeUpdate ()

void tncTxByte (uint8_t value)

Write value to the TNC buffer.

void tncNMEATime ()

Generate the GPS NMEA standard UTC time stamp.

void tncNMEAFix ()

Generate the GPS NMEA standard latitude/longitude fix.

void tncStatusPacket ()

Generate the plain text status packet.

void tncGPGGAPacket ()

Generate the GPS NMEA-0183 $GPGGA packet.

void tncGPRMCPacket ()

Generate the GPS NMEA-0183 $GPRMC packet.

void tncTxPacket (TNC_PACKET_TYPE tncPacketType)

Prepare an AX.25 data packet.

Variables

uint8_t TNC_AX25_HEADER [30]

uint8_t tncLastBit

uint8_t tncPacketType

TNC_MODE tncMode

Current mode of the 1200 bps state machine.

uint8_t tncBitCount

Counter for each bit (0 - 7) that we are going to transmit.

uint8_t tncShift

A shift register that holds the data byte as we bit shift it for transmit.

uint8_t tncIndex

Index into the APRS header and data array for each byte as we transmit it.

uint8_t tncLength

The number of bytes in the message portion of the AX.25 message.

uint8_t tncBitStuff

A copy of the last 5 bits we've transmitted to determine if we need to bit stuff on the next bit.

uint8_t * tncBufferPnt

Pointer to TNC buffer as we save each byte during message preparation.

uint8_t tncBuffer [TNC_BUFFER_SIZE]

Buffer to hold the message portion of the AX.25 packet as we prepare it.

uint16_t tncTestCount

uint16_t timeNCO

16-bit NCO where the upper 8-bits are used to index into the frequency generation table.

uint16_t timeNCOFreq

Audio tone NCO update step (phase).

uint8_t timeLowRateCount

Counter used to deciminate down from the 104uS to 833uS interrupt rate. (9600 to 1200 baud).

Detailed Description

Functions that provide a subset of the TNC functions.

Define Documentation

#define TNC_BUFFER_SIZE 80

#define TNC_DWELL_TIME 3600

#define TNC_TIMESLOT 55

The UTC time in seconds to send an APRS packet.

Referenced by main().

#define TNC_TX_DELAY 45

The number of start flag bytes to send before the packet message. (300mS).

Referenced by tncTimeUpdate().

Enumeration Type Documentation

enum TNC_MODE

TNC state machine.

Enumerator:

TNC_TX_READY	Ready to accept a new message.
TNC_TX_SYNC	Send the sync pattern at the start of the message. This is typically 200-300mS.
TNC_TX_HEADER	Send the header that contains the callsign, path, and SSID information.
TNC_TX_DATA	Send the text message data.
TNC_TX_END	Send the end sequence.

Function Documentation

void tncGPGGAPacket ( )

Generate the GPS NMEA-0183 $GPGGA packet.

Data is written through the tncTxByte callback function.

References GPS_NO_FIX, gpsGetFixType(), gpsNMEAChecksum(), gpsPosition, tncBuffer, tncLength, tncNMEAFix(), tncNMEATime(), and tncTxByte().

Referenced by tncTxPacket().

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void tncGPRMCPacket ( )

Generate the GPS NMEA-0183 $GPRMC packet.

Data is written through the tncTxByte callback function.

References GPS_NO_FIX, gpsGetFixType(), gpsNMEAChecksum(), gpsPosition, tncBuffer, tncLength, tncNMEAFix(), tncNMEATime(), and tncTxByte().

Referenced by tncTxPacket().

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void tncInit ( )

References timeLowRateCount, timeNCO, timeNCOFreq, TNC_BOOT_MESSAGE, TNC_TX_READY, tncLastBit, tncMode, tncPacketType, and tncTestCount.

Referenced by main().

bool_t tncIsFree ( )

Determine if the hardware if ready to transmit a 1200 baud packet.

Returns:: true if ready; otherwise false

References TNC_TX_READY, and tncMode.

Referenced by psk31TxPacket().

void tncNMEAFix ( )

Generate the GPS NMEA standard latitude/longitude fix.

Data is written through the tncTxByte callback function.

References gpsPosition, and tncTxByte().

Referenced by tncGPGGAPacket(), and tncGPRMCPacket().

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void tncNMEATime ( )

Generate the GPS NMEA standard UTC time stamp.

Data is written through the tncTxByte callback function.

References gpsPosition, and tncTxByte().

Referenced by tncGPGGAPacket(), and tncGPRMCPacket().

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void tncStatusPacket ( )

Generate the plain text status packet.

Data is written through the tncTxByte callback function.

References GPS_2D_FIX, GPS_3D_FIX, GPS_NO_FIX, gpsGetFixType(), gpsPosition, lm92GetTemp(), timeHours, timeMinutes, timeSeconds, and tncTxByte().

Referenced by tncTxPacket().

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void tncTimeUpdate ( )

References DDS_MODE_POWERDOWN, ddsPTT(), ddsSetFTW(), ddsSetMode(), freqTable, logSetDisableFlag(), sysPAOutput(), timeLowRateCount, timeNCO, timeNCOFreq, TNC_AX25_HEADER, TNC_TX_DATA, TNC_TX_DELAY, TNC_TX_END, TNC_TX_HEADER, TNC_TX_READY, TNC_TX_SYNC, tncBitCount, tncBitStuff, tncBuffer, tncIndex, tncLastBit, tncLength, tncMode, and tncShift.

Referenced by timeUpdate().

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void tncTxByte ( uint8_t value )

Write value to the TNC buffer.

Maintain the pointer and length to the buffer. The pointer tncBufferPnt and tncLength must be set before calling this function for the first time.

Parameters:

value

to save to telemetry buffer

References tncBufferPnt, and tncLength.

Referenced by tncGPGGAPacket(), tncGPRMCPacket(), tncNMEAFix(), tncNMEATime(), tncStatusPacket(), and tncTxPacket().

void tncTxPacket ( TNC_PACKET_TYPE tncPacketType )

Prepare an AX.25 data packet.

Each time this method is called, it automatically rotates through 1 of 4 messages.

References DDS_MODE_APRS, ddsPTT(), ddsSetAmplitude(), ddsSetMode(), logSetDisableFlag(), psk31IsFree(), sysCRC16(), sysPAOutput(), TIME_MODE_APRS, timeSetMode(), TNC_AX25_HEADER, TNC_BOOT_MESSAGE, TNC_GGA, TNC_RMC, TNC_STATUS, TNC_TX_READY, TNC_TX_SYNC, tncBitCount, tncBuffer, tncBufferPnt, tncGPGGAPacket(), tncGPRMCPacket(), tncIndex, tncLastBit, tncLength, tncMode, tncShift, tncStatusPacket(), and tncTxByte().

Referenced by main().

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Variable Documentation

uint8_t timeLowRateCount

Counter used to deciminate down from the 104uS to 833uS interrupt rate. (9600 to 1200 baud).

Referenced by tncInit(), and tncTimeUpdate().

uint16_t timeNCO

16-bit NCO where the upper 8-bits are used to index into the frequency generation table.

Referenced by tncInit(), and tncTimeUpdate().

uint16_t timeNCOFreq

Audio tone NCO update step (phase).

Referenced by tncInit(), and tncTimeUpdate().

uint8_t TNC_AX25_HEADER[30]

Initial value:

 
{ 
    'A' << 1, 'P' << 1, 'R' << 1, 'S' << 1, ' ' << 1, ' ' << 1, 0x60, 
    'K' << 1, 'D' << 1, '7' << 1, 'L' << 1, 'M' << 1, 'O' << 1, 0x76, 
    'G' << 1, 'A' << 1, 'T' << 1, 'E' << 1, ' ' << 1, ' ' << 1, 0x60, 
    'W' << 1, 'I' << 1, 'D' << 1, 'E' << 1, '3' << 1, ' ' << 1, 0x67, 
    0x03, 0xf0 
}

Referenced by tncTimeUpdate(), and tncTxPacket().

uint8_t tncBitCount

Counter for each bit (0 - 7) that we are going to transmit.

Referenced by tncTimeUpdate(), and tncTxPacket().

uint8_t tncBitStuff

A copy of the last 5 bits we've transmitted to determine if we need to bit stuff on the next bit.

Referenced by tncTimeUpdate().

uint8_t tncBuffer[TNC_BUFFER_SIZE]

Buffer to hold the message portion of the AX.25 packet as we prepare it.

Referenced by tncGPGGAPacket(), tncGPRMCPacket(), tncTimeUpdate(), and tncTxPacket().

uint8_t* tncBufferPnt

Pointer to TNC buffer as we save each byte during message preparation.

Referenced by tncTxByte(), and tncTxPacket().

uint8_t tncIndex

Index into the APRS header and data array for each byte as we transmit it.

Referenced by tncTimeUpdate(), and tncTxPacket().

uint8_t tncLastBit

Referenced by tncInit(), tncTimeUpdate(), and tncTxPacket().

uint8_t tncLength

The number of bytes in the message portion of the AX.25 message.

Referenced by tncGPGGAPacket(), tncGPRMCPacket(), tncTimeUpdate(), tncTxByte(), and tncTxPacket().

TNC_MODE tncMode

Current mode of the 1200 bps state machine.

Referenced by tncInit(), tncIsFree(), tncTimeUpdate(), and tncTxPacket().

uint8_t tncPacketType

Referenced by tncInit().

uint8_t tncShift

A shift register that holds the data byte as we bit shift it for transmit.

Referenced by tncTimeUpdate(), and tncTxPacket().

uint16_t tncTestCount

Referenced by tncInit().


Defines
#define	TNC_TX_DELAY 45
	The number of start flag bytes to send before the packet message. (300mS).
#define	TNC_TIMESLOT 55
	The UTC time in seconds to send an APRS packet.
#define	TNC_BUFFER_SIZE 80
#define	TNC_DWELL_TIME 3600
Enumerations
enum	TNC_MODE { TNC_TX_READY, TNC_TX_SYNC, TNC_TX_HEADER, TNC_TX_DATA, TNC_TX_END }
	TNC state machine. More...
Functions
void	tncInit ()
bool_t	tncIsFree ()
	Determine if the hardware if ready to transmit a 1200 baud packet.
void	tncTimeUpdate ()
void	tncTxByte (uint8_t value)
	Write value to the TNC buffer.
void	tncNMEATime ()
	Generate the GPS NMEA standard UTC time stamp.
void	tncNMEAFix ()
	Generate the GPS NMEA standard latitude/longitude fix.
void	tncStatusPacket ()
	Generate the plain text status packet.
void	tncGPGGAPacket ()
	Generate the GPS NMEA-0183 $GPGGA packet.
void	tncGPRMCPacket ()
	Generate the GPS NMEA-0183 $GPRMC packet.
void	tncTxPacket (TNC_PACKET_TYPE tncPacketType)
	Prepare an AX.25 data packet.
Variables
uint8_t	TNC_AX25_HEADER [30]
uint8_t	tncLastBit
uint8_t	tncPacketType
TNC_MODE	tncMode
	Current mode of the 1200 bps state machine.
uint8_t	tncBitCount
	Counter for each bit (0 - 7) that we are going to transmit.
uint8_t	tncShift
	A shift register that holds the data byte as we bit shift it for transmit.
uint8_t	tncIndex
	Index into the APRS header and data array for each byte as we transmit it.
uint8_t	tncLength
	The number of bytes in the message portion of the AX.25 message.
uint8_t	tncBitStuff
	A copy of the last 5 bits we've transmitted to determine if we need to bit stuff on the next bit.
uint8_t *	tncBufferPnt
	Pointer to TNC buffer as we save each byte during message preparation.
uint8_t	tncBuffer [TNC_BUFFER_SIZE]
	Buffer to hold the message portion of the AX.25 packet as we prepare it.
uint16_t	tncTestCount
uint16_t	timeNCO
	16-bit NCO where the upper 8-bits are used to index into the frequency generation table.
uint16_t	timeNCOFreq
	Audio tone NCO update step (phase).
uint8_t	timeLowRateCount
	Counter used to deciminate down from the 104uS to 833uS interrupt rate. (9600 to 1200 baud).