Silicon Laboratories SI2493/57/34/15/04, SI2494/39 manual Modem Interrupt Service Sample Code

AN93

Modem Interrupt Service Sample Code

The following is the C code for the modem ISR. Also refer to "Figure 76. Parallel- or SPI-PortInterrupt-Service Flowchart" for more explanations. Please contact Silicon Labs to obtain a complete C8051F12xx project bundle.

// Macros for modem ISR readability

#define RXFInterrupt	( modem_status	& SiRXF )
#define TXEInterrupt	( modem_status	& (		SiTXE &	modem_control ) )
#define TimerInterrupt ( !( modem_status &			SiREM ) &&		!RXFInterrupt && !rxf_processed )
#define U70Interrupt	( modem_status	& (		SiINT &	( modem_status >> 1 ) ) )
#define RTSIsSet	( modem_status	& SiRTSb )
#define ClearRTS	( modem_control		&=	~SiRTSb	)
#define ClearRXF	( modem_control		&=	~SiRXF )
#define ClearTXE	( modem_control		&=	~SiTXE )
#define ClearINTM	( modem_control		&=	~SiINTM	)
#define rxBufferSize	gModemToUARTBufferSize
#define ReadModemStatus	modem_status =	readModem( HIR1 )
#define readModemByte	pushByteToUART(		readModem(		HIR0 ) )
//-----------------------------------------------------------------------------

// Interrupt service routine

//-----------------------------------------------------------------------------

// modemInterrupt()

//-----------------------------------------------------------------------------

//Invoked whenever the modem issues an interrupt: this is meant as reference

//code for parallel-port/SPI interrupt service.

//
// Parameters:		None
// Return value: None
//-----------------------------------------------------------------------------
void modemInterrupt( void ) interrupt 2
{
char	modem_status;
char	modem_control; // Modem			control before writing (written only if modifed)
char	control_update = 0;		//	Tracks whether control register was modified, needs updating
char	rxf_processed = 0;
int BytesSent;
int BytesReceived = 0;
char	SFRPAGE_SAVE;
EA =	0;		//	Disable global interrupt
EA =	0;		//	Dummy operation required by MCU, as per MCU data sheet
SFRPAGE_SAVE = SFRPAGE;			//	Save Current SFR page
ReadModemStatus;			//	Read HIR1 to get current status

//Set default write value. Always write the RXF and TXE bits to 1 by default

//to avoid inadvertently clearing those interrupts

modem_control = modem_status SiTXE SiRXF;

//Clear the RTS bit if it's set. The part comes out of reset with RTS set.

//RTS will have no effect unless the modem gets the AT\Q3 command.

//If RTS isn't needed this code can be removed.

if ( RTSIsSet )
{
ClearRTS;	// Clear the RTSb so data enters FIFO

control_update = 1;

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