hndshake.c

CML CMX868 modem

unsigned char orig_V22_600()
{
	return(NYI);
}

unsigned char orig_V21()
{
	return(NYI);
}

unsigned char orig_212a()
{
	return(NYI);
}

unsigned char orig_202()
{
	return(NYI);
}

unsigned char orig_202r()
{
	return(NYI);
}

unsigned char orig_103()
{
// Stage 1
	CMXRXMODE &= 0x0E00;					// Mask Rx Gain settings
	CMXRXMODE ^= 0x7038;					// Setup Rx for high band Bell 103 300bps and auto-equaliser disabled
								// Descrambler Disabled and synchronous operation
	wr16_cbus(CMXRXMODE_ADDR,CMXRXMODE);			// Update Rx Mode CBUS register

	if (unscram1sdet(5) != OK) return(NOCARRIER);		// Detect unscram 1's for 150ms (1's detect has approx 100ms (32bits) response time)

// Stage 2
	DCDN = 0;						// Clear DCDN line.
	DCDIND = 1;						// Turn on CD LED.

	GPT1 = 77;						// Start 770ms timer

	do {
		if (KEYABORT || (GPT6 == 0))
		{						// Return No Carrier message if key pushed or
			return(NOCARRIER);			// if wait carrier after dial timer has expired
		}
	} while (GPT1 >= 32);					// Wait until 450ms has expired

// Stage 3
	CMXTXDATA = 0xFF;
	wr_cbus(CMXTXDATA_ADDR,CMXTXDATA);			// Ensure Tx data reg is all 1's

	CMXTXMODE &= 0x0E00;					// Mask Tx Gain settings
	CMXTXMODE ^= 0x601F;					// Setup Tx for low band Bell 103 300bps, no guard tone
								// No Guard tone, scram disabled, sync operation, Tx data byte reg
	wr16_cbus(CMXTXMODE_ADDR,CMXTXMODE);			// Update Tx Mode CBUS register
// Stage 4
	do {
		if (KEYABORT || (GPT6 == 0))
		{						// Return No Carrier message if key pushed or
			return(NOCARRIER);			// if wait carrier after dial timer has expired
		}
	} while (GPT1 != 0);					// Ensure 770ms timer has expired

// Stage 5
	async_setup();						// Configure Tx/Rx for async operation (settings extracted from S25 and S26)

	return(CON300);						// Return Connect 300
}

void ans_tone()
{
// Stage 1 Tx No Tone for 2.2s
	CMXTXMODE &= 0x0E00;					// Mask Tx Gain settings
	CMXTXMODE ^= 0x1000;					// Initially setup Tx for tones, no guard tone
								// No Guard tone, scrambler Disabled, fixed tone, no tone
	wr16_cbus(CMXTXMODE_ADDR,CMXTXMODE);			// Update Tx Mode CBUS register

	GPT3 = 22;						// Start 2.2s timer
	while(GPT3 != 0)
		continue;

// Stage 2 Tx 2100Hz for 3.3s
	CMXTXMODE ^= 0x000A;					// No Guard tone, scrambler Disabled, fixed tone, 2100Hz
	wr16_cbus(CMXTXMODE_ADDR,CMXTXMODE);			// Update Tx Mode CBUS register

	GPT3 = 33;						// Start 3.3s timer
	while(GPT3 != 0)
		continue;

// Stage 3 Tx No Tone for 80ms
	CMXTXMODE &= 0xFF00;					// No Guard tone, scrambler Disabled, fixed tone, no tone
	wr16_cbus(CMXTXMODE_ADDR,CMXTXMODE);			// Update Tx Mode CBUS register

	GPT1 = 8;						// Start 80ms timer
	while(GPT1 != 0)
		continue;
}

unsigned char ans_V22bis()
{
	unsigned char det32ones = 0;
	unsigned char tx2400flag = 0;
	unsigned char gotS1pattern = 0;

// Stage 1 Tx unscrambled 1's
	CMXRXMODE &= 0x0E00;					// Mask Rx Gain settings
	CMXRXMODE ^= 0xC0F8;					// Setup Rx for low band V.22 1200bps and auto-equaliser disabled
								// Descrambler enabled, synchronous operation
	wr16_cbus(CMXRXMODE_ADDR,CMXRXMODE);			// Update Rx Mode CBUS register

	CMXTXDATA = 0xFF;
	wr_cbus(CMXTXDATA_ADDR,CMXTXDATA);			// Ensure Tx data reg is all 1's

	CMXTXMODE &= 0x0E00;					// Mask Tx Gain settings
	CMXTXMODE ^= (((int) S23) << 1) & 0x0180;		// Extract Guard Tone setting from S23.
	CMXTXMODE ^= 0xD01F;					// Initially setup Tx for high band V.22 1200bps
								// Scrambler Disabled, sync and Tx data byte
	wr16_cbus(CMXTXMODE_ADDR,CMXTXMODE);			// Update CBUS register

// Stage 2 Look for scrambled 1's and also S1 pattern if V22bis selected
	GPT1 = 24;						// Start 270ms timer (scram 1's detect has approx 30ms (32 bits) response time)
	do {
		DelayMs(5);					// Insert 5ms polling delay 
		if (KEYABORT || (GPT6 == 0))
		{						// Return No Carrier message if key pushed or
			return(NOCARRIER);			// if general purpose timer (S18) has expired
		}
		CMXSTAT = rd16_cbus(CMXSTAT_ADDR);		// Read status register and update shadow register

		if (!RXENERGYDET || !CONTA || !CONTB)		// If rx energy or scram 1's are not detected
		{
			GPT1 = 24;				// Restart scram 1's detect timer
		}

		if ((S27 & 0b11110000) == PROTB0)		// Look for S1 Pattern if V22bis was selected 
		{
			if (!FALLBACK)				// If modulation fallback is not enabled 
			{					// prevent detection of V22 handshaking sequence
				GPT1 = 24;			// by restarting scram 1's detect timer
			}
			if (RXENERGYDET && S1DET)
			{
				gotS1pattern = 1;		// Set flag to indicate S1 pattern was found
			}
		}
	} while(GPT1 != 0 && !gotS1pattern);			// Continue to loop until scram 1's detected for approx 270ms

	if (gotS1pattern)
	{
// Stage 3 If the S1 pattern was detected wait until it goes away
		do {						// Wait until end of S1 pattern
			DelayMs(5);				// Insert 5ms polling delay 
			if (KEYABORT || (GPT6 == 0))
			{					// Return No Carrier message if key pushed or
				return(NOCARRIER);		// if wait carrier after dial timer has expired
			}
			CMXSTAT = rd16_cbus(CMXSTAT_ADDR);	// Read status register and update shadow register
		} while(S1DET);					// Wait until S1 Pattern has gone

// Stage 4 Tx S1 pattern for 100ms
		CMXTXMODE &= 0xFFF8;				// Now Tx S1 pattern
		wr16_cbus(CMXTXMODE_ADDR,CMXTXMODE);		// Update Tx Mode CBUS register

		GPT1 = 60;					// Start 600ms timer
		do {
			if (KEYABORT || (GPT6 == 0))
			{					// Return No Carrier message if key pushed or
				return(NOCARRIER);		// if general purpose timer (S18) has expired
			}
		} while(GPT1 >= 50);				// Wait for 100ms timer to expire

// Stage 5 Tx scrambled 1's
		CMXTXMODE &= 0xFF98;				// Unmask scrambler and Tx Data source bit settings
		CMXTXMODE ^= 0x0067;				// Scrambler enabled and Tx data byte
		wr16_cbus(CMXTXMODE_ADDR,CMXTXMODE);		// Update Tx Mode CBUS register

// Stage 6 Wait for 300ms timer to expire before enabling Rx Auto-Equaliser (will ensure it is receiving randomised data)
		do {
			if (KEYABORT || (GPT6 == 0))
			{					// Return No Carrier message if key pushed or
				return(NOCARRIER);		// if general purpose timer (S18) has expired
			}
		} while (GPT1 >= 30);				// Wait until 300ms has expired

		AUTO_EQU = 1;					// Enable Rx Auto-Equaliser for training (must be enabled for 2400bps operation)
		wr16_cbus(CMXRXMODE_ADDR,CMXRXMODE);		// Update Rx Mode CBUS register

// Stage 7 wait for 450ms timer to expire
		do {
			if (KEYABORT || (GPT6 == 0))
			{					// Return No Carrier message if key pushed or
				return(NOCARRIER);		// if general purpose timer (S18) has expired
			}
		} while (GPT1 >= 15);				// Wait until 450ms has expired

// Stage 8 Switch Rx Mode to 2400bps (Detectors and associated status flags will be reset)
		CMXRXMODE &= 0x0FFF;				// Unmask Rx Mode bit settings
		CMXRXMODE ^= 0xE000;				// Setup Rx for low band V.22bis 2400bps
		wr16_cbus(CMXRXMODE_ADDR,CMXRXMODE);		// Update Rx Mode CBUS register

// Stage 9 Wait until 32 continuous scram 1's at 2400bps are detected and the transmitter has switched to 2400bps scram 1's
		do {
			DelayMs(5);				// Insert 5ms polling delay 
			if (KEYABORT || (GPT6 == 0))
			{					// Return No Carrier message if key pushed or
				return(NOCARRIER);		// if wait carrier after dial timer has expired
			}
			if (!tx2400flag)
			{
				if (GPT1 == 0)			// Check if 600ms timer has expired
				{
					CMXTXMODE &= 0x0FFF;	// Unmask Tx Mode bit settings
					CMXTXMODE ^= 0xF000;	// Setup Tx for high band V.22 bis 2400bps
					wr16_cbus(CMXTXMODE_ADDR,CMXTXMODE);	// Update Tx Mode CBUS register	

					GPT1 = 20;		// Load 200ms Timer
					tx2400flag = 1;
				}
			}
			CMXSTAT = rd16_cbus(CMXSTAT_ADDR);	// Read status register and update shadow register

			if (RXENERGYDET && CONTA && CONTB && !det32ones)
			{
				DCDN = 0;			// Clear DCDN line.
				DCDIND = 1;			// Turn on CD LED.
				det32ones = 1;			// Set detect 32 1's flag
			}
		} while(!RXENERGYDET || !CONTA || !CONTB || !tx2400flag);	// Wait until 2400bps cont 1's is detected and
										// 2400bps has started transmitting
// Stage 10 Ensure final 200ms timer has expired
		do {
			if (KEYABORT || (GPT6 == 0))
			{					// Return No Carrier message if key pushed or
				return(NOCARRIER);		// if general purpose timer (S18) has expired
			}
		} while (GPT1 != 0);				// Ensure 200ms timer has expired
	}
	else
	{
// Stage 11 Tx scrambled 1's
		CMXTXMODE &= 0xFF9F;				// Unmask scrambler bit settings
		CMXTXMODE ^= 0x0060;				// Enable scrambler
		wr16_cbus(CMXTXMODE_ADDR,CMXTXMODE);		// Update Tx Mode CBUS register

		AUTO_EQU = USER_AUTO_EQU;			// Extract Auto Equaliser setting from S24.
		wr16_cbus(CMXRXMODE_ADDR,CMXRXMODE);		// Update Rx Mode CBUS register

// Stage 12 Wait for 770ms timer to expire
		GPT1 = 77;					// Start 770ms timer
		do {
			if (KEYABORT || (GPT6 == 0))
			{					// Return No Carrier message if key pushed or
				return(NOCARRIER);		// if general purpose timer (S18) has expired
			}
		} while (GPT1 != 0);				// Wait until 770ms has expired

		DCDN = 0;					// Clear DCDN line.
		DCDIND = 1;					// Turn on CD LED.
	}
// Stage 13
	async_setup();						// Configure Tx/Rx for async operation (settings extracted from S25 and S26)

	if (!gotS1pattern)
	{
		return(CON1200);				// Return Connect 1200
	}
	else
	{
		return(CON2400);				// Return Connect 2400
	}
}

unsigned char ans_V23()
{
// Stage 1 Tx unscrambled cont 1's
	CMXRXMODE &= 0x0E00;					// Mask Rx Gain settings
	CMXRXMODE ^= 0x4038;					// Setup Rx for V23 75bps and auto-equaliser disabled
								// Descrambler disabled, synchronous operation
	wr16_cbus(CMXRXMODE_ADDR,CMXRXMODE);			// Update Rx Mode CBUS register

	CMXTXDATA = 0xFF;
	wr_cbus(CMXTXDATA_ADDR,CMXTXDATA);			// Ensure Tx data reg is all 1's

	CMXTXMODE &= 0x0E00;					// Mask Tx Gain settings
	CMXTXMODE ^= 0x501F;					// Setup Tx for V23 1200bps, no guard tones
								// Scrambler disabled, sync operation, Tx data byte
	wr16_cbus(CMXTXMODE_ADDR,CMXTXMODE);			// Update CBUS register

// Stage 2 Detect unscram 1's for 150ms (use FSK demod output for this low baud rate detection)
	GPT1 = 15;						// Start timer
	do {
		if (KEYABORT || (GPT6 == 0))
		{						// Return No Carrier message if key pushed or
			return(NOCARRIER);			// if GPT6 has expired
		}
		CMXSTAT = rd16_cbus(CMXSTAT_ADDR);		// Read status register and update shadow register
		if (!RXENERGYDET || !FSKOUT)			// If rx energy not detected or FSK demod output low
		{
			GPT1 = 15;				// Restart unscram 1's detect timer
		}
	} while(GPT1 != 0);					// Continue to loop until unscram 1's detected for 150ms

// Stage 3
	async_setup();						// Configure Tx/Rx for async operation (settings extracted from S25 and S26)

	DCDN = 0;						// Clear DCDN line.
	DCDIND = 1;						// Turn on CD LED.

	return(CON120075);					// Return Connect 1200/75
}

unsigned char ans_V23r()
{
	return(NYI);
}

unsigned char ans_V22_600()
{
	return(NYI);
}

unsigned char ans_V21()
{
	return(NYI);
}

unsigned char ans_212a()
{
	return(NYI);
}

unsigned char ans_202()
{
	return(NYI);
}

unsigned char ans_202r()
{
	return(NYI);
}

unsigned char ans_103()
{
// Stage 1 Tx unscrambled cont 1's
	CMXRXMODE &= 0x0E00;					// Mask Rx Gain settings
	CMXRXMODE ^= 0x6038;					// Setup Rx for low band Bell 103 300bps and auto-equaliser disabled
								// Descrambler disabled, synchronous operation
	wr16_cbus(CMXRXMODE_ADDR,CMXRXMODE);			// Update Rx Mode CBUS register

	CMXTXDATA = 0xFF;
	wr16_cbus(CMXTXDATA_ADDR,CMXTXDATA);			// Ensure Tx data reg is all 1's

	CMXTXMODE &= 0x0E00;					// Mask Tx Gain settings
	CMXTXMODE ^= 0x701F;					// Setup Tx for high band Bell 103 300bps, no guard tones
								// Scrambler disabled, sync operation and Tx data byte
	wr16_cbus(CMXTXMODE_ADDR,CMXTXMODE);			// Update CBUS register

// Stage 2
	if (unscram1sdet(5) != OK) return(NOCARRIER);		// Detect unscram 1's for 150ms (1's detect has approx 100ms (32bits) response time)

// Stage 3
	async_setup();						// Configure Tx/Rx for async operation (settings extracted from S25 and S26)

	DCDN = 0;						// Clear DCDN line.
	DCDIND = 1;						// Turn on CD LED.

	return(CON300);						// Return Connect 300
}

void async_setup()
{
	CMXTXMODE &= 0xFFE0;					// Unmask Tx Data format bit settings
	CMXTXMODE ^= ((((int) S25) >> 3) & 0x001F);		// Extract Tx Data/Stop bit and async mode settings from S25.
	wr16_cbus(CMXTXMODE_ADDR,CMXTXMODE);			// Update Tx Mode CBUS register

	RXUSART = 1;						// Ensure Rx USART is enabled 
	CMXRXMODE &= 0xFFE0;					// Unmask Rx USART bit settings
	CMXRXMODE ^= ((((int) S26) >> 3) & 0x001F);		// Extract Rx Data/parity and async mode settings from S26.
	wr16_cbus(CMXRXMODE_ADDR,CMXRXMODE);			// Update Rx Mode CBUS register
}

unsigned char unscram1sdet(unsigned char dettime)		// Uses general purpose timers GPT1 and GPT6
{
	GPT1 = dettime;						// Start timer
	do {
		DelayMs(5);					// Insert 5ms polling delay 
		if (KEYABORT || (GPT6 == 0))
		{						// Return No Carrier message if key pushed or
			return(NOCARRIER);			// if GPT6 has expired
		}
		CMXSTAT = rd16_cbus(CMXSTAT_ADDR);		// Read status register and update shadow register
		if (!RXENERGYDET || !CONTA || CONTB)		// If rx energy or unscram 1's are not detected
		{
			GPT1 = dettime;				// Restart unscram 1's detect timer
		}
	} while(GPT1 != 0);					// Continue to loop until unscram 1's detected for specified time
	
	return(OK);
}