IAR AVR 单从机 TWI源码

只看该作者 · 2009-11-30 22:29

//main.c

#include <ioavr.h>
#include <inavr.h>
#include "TWI_Slave.h"

// Sample TWI transmission commands
#define TWI_CMD_MASTER_WRITE 0x10
#define TWI_CMD_MASTER_READ 0x20

// The AVR can be waken up by a TWI address match from all sleep modes,
// But it only wakes up from other TWI interrupts when in idle mode.
// If POWER_MANAGEMENT_ENABLED is defined the device will enter power-down
// mode when waiting for a new command and enter idle mode when waiting
// for TWI receives and transmits to finish.
#define POWER_MANAGEMENT_ENABLED

// When there has been an error, this function is run and takes care of it
unsigned char TWI_Act_On_Failure_In_Last_Transmission ( unsigned char TWIerrorMsg );

void main( void )
{
unsigned char messageBuf[TWI_BUFFER_SIZE];
unsigned char TWI_slaveAddress;

// LED feedback port - connect port B to the STK500 LEDS
DDRB = 0xFF; // Set to ouput
PORTB = 0x55; // Startup pattern

// Own TWI slave address
TWI_slaveAddress = 0x10;

// Initialise TWI module for slave operation. Include address and/or enable General Call.
TWI_Slave_Initialise( (unsigned char)((TWI_slaveAddress<<TWI_ADR_BITS) | (TRUE<<TWI_GEN_BIT) ));

__enable_interrupt();

// Start the TWI transceiver to enable reseption of the first command from the TWI Master.
TWI_Start_Transceiver();

// This example is made to work together with the AVR315 TWI Master application note. In adition to connecting the TWI
// pins, also connect PORTB to the LEDS. The code reads a message as a TWI slave and acts according to if it is a
// general call, or an address call. If it is an address call, then the first byte is considered a command byte and
// it then responds differently according to the commands.

// This loop runs forever. If the TWI is busy the execution will just continue doing other operations.
for(;;)
{
  #ifdef POWER_MANAGEMENT_ENABLED
// Sleep while waiting for TWI transceiver to complete or waiting for new commands.
// If we have data in the buffer, we can't enter sleep because we have to take care
// of it first.
// If the transceiver is busy, we enter idle mode because it will wake up by all TWI
// interrupts.
// If the transceiver not is busy, we can enter power-down mode because next receive
// should be a TWI address match and it wakes the device up from all sleep modes.
if( ! TWI_statusReg.RxDataInBuf ) {
if(TWI_Transceiver_Busy()) {
   MCUCR = (1<<SE)|(0<<SM2)|(0<<SM1)|(0<<SM0); // Enable sleep with idle mode
} else {
   MCUCR = (1<<SE)|(0<<SM2)|(1<<SM1)|(0<<SM0); // Enable sleep with power-down mode
}
__sleep();
} else {
__no_operation(); // There is data in the buffer, code below takes care of it.
}
  #else // No power management
// Here you can add your own code that should be run while waiting for the TWI to finish
__no_operation(); // Put own code here.
  #endif

只看该作者 · 2009-11-30 22:30

// Check if the TWI Transceiver has completed an operation.
  if ( ! TWI_Transceiver_Busy() )
  {
// Check if the last operation was successful
if ( TWI_statusReg.lastTransOK )
{
// Check if the last operation was a reception
if ( TWI_statusReg.RxDataInBuf )
{
   TWI_Get_Data_From_Transceiver(messageBuf, 2);
   // Check if the last operation was a reception as General Call
   if ( TWI_statusReg.genAddressCall )
   {
      // Put data received out to PORTB as an example.
      PORTB = messageBuf[0];
   }
   else // Ends up here if the last operation was a reception as Slave Address Match
   {
      // Example of how to interpret a command and respond.

      // TWI_CMD_MASTER_WRITE stores the data to PORTB
      if (messageBuf[0] == TWI_CMD_MASTER_WRITE)
      {
      PORTB = messageBuf[1];
      }
      // TWI_CMD_MASTER_READ prepares the data from PINB in the transceiver buffer for the TWI master to fetch.
      if (messageBuf[0] == TWI_CMD_MASTER_READ)
      {
      messageBuf[0] = PINB;
      TWI_Start_Transceiver_With_Data( messageBuf, 1 );
      }
   }
}
else // Ends up here if the last operation was a transmission
{
      __no_operation(); // Put own code here.
}
// Check if the TWI Transceiver has already been started.
// If not then restart it to prepare it for new receptions.
if ( ! TWI_Transceiver_Busy() )
{
   TWI_Start_Transceiver();
}
}
else // Ends up here if the last operation completed unsuccessfully
{
TWI_Act_On_Failure_In_Last_Transmission( TWI_Get_State_Info() );
}
  }
}
}

unsigned char TWI_Act_On_Failure_In_Last_Transmission ( unsigned char TWIerrorMsg )
{
         // A failure has occurred, use TWIerrorMsg to determine the nature of the failure
         // and take appropriate actions.
         // Se header file for a list of possible failures messages.

         // This very simple example puts the error code on PORTB and restarts the transceiver with
         // all the same data in the transmission buffers.
PORTB = TWIerrorMsg;
TWI_Start_Transceiver();

return TWIerrorMsg;
}

/*
// A simplified example.
// This will store data received on PORTB, and increment it before sending it back.

TWI_Start_Transceiver( );

for(;;)
{
  if ( ! TWI_Transceiver_Busy() )
  {
if ( TWI_statusReg.RxDataInBuf )
{
TWI_Get_Data_From_Transceiver(&temp, 1);
PORTB = temp;
}
temp = PORTB + 1;
TWI_Start_Transceiver_With_Data(&temp, 1);
  }
  __no_operation(); // Do something else while waiting
}
}

只看该作者 · 2009-11-30 22:30

*/

//slave.c

#include "ioavr.h"
#include "inavr.h"
#include "TWI_slave.h"

static unsigned char TWI_buf[TWI_BUFFER_SIZE]; // Transceiver buffer. Set the size in the header file
static unsigned char TWI_msgSize = 0;       // Number of bytes to be transmitted.
static unsigned char TWI_state = TWI_NO_STATE; // State byte. Default set to TWI_NO_STATE.

// This is true when the TWI is in the middle of a transfer
// and set to false when all bytes have been transmitted/received
// Also used to determine how deep we can sleep.
static unsigned char TWI_busy = 0;

union TWI_statusReg_t TWI_statusReg = {0};    // TWI_statusReg is defined in TWI_Slave.h

/****************************************************************************
Call this function to set up the TWI slave to its initial standby state.
Remember to enable interrupts from the main application after initializing the TWI.
Pass both the slave address and the requrements for triggering on a general call in the
same byte. Use e.g. this notation when calling this function:
TWI_Slave_Initialise( (TWI_slaveAddress<<TWI_ADR_BITS) | (TRUE<<TWI_GEN_BIT) );
The TWI module is configured to NACK on any requests. Use a TWI_Start_Transceiver function to
start the TWI.
****************************************************************************/
void TWI_Slave_Initialise( unsigned char TWI_ownAddress )
{
TWAR = TWI_ownAddress;                // Set own TWI slave address. Accept TWI General Calls.
TWCR = (1<<TWEN)|                      // Enable TWI-interface and release TWI pins.
   (0<<TWIE)|(0<<TWINT)|             // Disable TWI Interupt.
   (0<<TWEA)|(0<<TWSTA)|(0<<TWSTO)|    // Do not ACK on any requests, yet.
   (0<<TWWC);                      //
TWI_busy = 0;
}

/****************************************************************************
Call this function to test if the TWI_ISR is busy transmitting.
****************************************************************************/
unsigned char TWI_Transceiver_Busy( void )
{
return TWI_busy;
}

/****************************************************************************
Call this function to fetch the state information of the previous operation. The function will hold execution (loop)
until the TWI_ISR has completed with the previous operation. If there was an error, then the function
will return the TWI State code.
****************************************************************************/
unsigned char TWI_Get_State_Info( void )
{
while ( TWI_Transceiver_Busy() ) {}       // Wait until TWI has completed the transmission.
return ( TWI_state );                // Return error state.
}

/****************************************************************************
Call this function to send a prepared message, or start the Transceiver for reception. Include
a pointer to the data to be sent if a SLA+W is received. The data will be copied to the TWI buffer.
Also include how many bytes that should be sent. Note that unlike the similar Master function, the
Address byte is not included in the message buffers.
The function will hold execution (loop) until the TWI_ISR has completed with the previous operation,
then initialize the next operation and return.
****************************************************************************/
void TWI_Start_Transceiver_With_Data( unsigned char *msg, unsigned char msgSize )
{
unsigned char temp;

while ( TWI_Transceiver_Busy() ) {}       // Wait until TWI is ready for next transmission.

TWI_msgSize = msgSize;                // Number of data to transmit.
for ( temp = 0; temp < msgSize; temp++ )    // Copy data that may be transmitted if the TWI Master requests data.
{
  TWI_buf[ temp ] = msg[ temp ];
}
TWI_statusReg.all = 0;
TWI_state    = TWI_NO_STATE ;
TWCR = (1<<TWEN)|                // TWI Interface enabled.
   (1<<TWIE)|(1<<TWINT)|          // Enable TWI Interupt and clear the flag.
   (1<<TWEA)|(0<<TWSTA)|(0<<TWSTO)|    // Prepare to ACK next time the Slave is addressed.
   (0<<TWWC);                //
TWI_busy = 1;
}

/****************************************************************************
Call this function to start the Transceiver without specifing new transmission data. Useful for restarting
a transmission, or just starting the transceiver for reception. The driver will reuse the data previously put
in the transceiver buffers. The function will hold execution (loop) until the TWI_ISR has completed with the
previous operation, then initialize the next operation and return.
****************************************************************************/

只看该作者 · 2009-11-30 22:31

void TWI_Start_Transceiver( void )
{
while ( TWI_Transceiver_Busy() ) {}       // Wait until TWI is ready for next transmission.
TWI_statusReg.all = 0;
TWI_state    = TWI_NO_STATE ;
TWCR = (1<<TWEN)|                // TWI Interface enabled.
   (1<<TWIE)|(1<<TWINT)|          // Enable TWI Interupt and clear the flag.
   (1<<TWEA)|(0<<TWSTA)|(0<<TWSTO)|    // Prepare to ACK next time the Slave is addressed.
   (0<<TWWC);                //
TWI_busy = 0;
}
/****************************************************************************
Call this function to read out the received data from the TWI transceiver buffer. I.e. first call
TWI_Start_Transceiver to get the TWI Transceiver to fetch data. Then Run this function to collect the
data when they have arrived. Include a pointer to where to place the data and the number of bytes
to fetch in the function call. The function will hold execution (loop) until the TWI_ISR has completed
with the previous operation, before reading out the data and returning.
If there was an error in the previous transmission the function will return the TWI State code.
****************************************************************************/
unsigned char TWI_Get_Data_From_Transceiver( unsigned char *msg, unsigned char msgSize )
{
unsigned char i;

while ( TWI_Transceiver_Busy() ) {}       // Wait until TWI is ready for next transmission.

if( TWI_statusReg.lastTransOK )          // Last transmission completed successfully.
{
  for ( i=0; i<msgSize; i++ )          // Copy data from Transceiver buffer.
  {
msg[ i ] = TWI_buf[ i ];
  }
  TWI_statusReg.RxDataInBuf = FALSE;    // Slave Receive data has been read from buffer.
}
return( TWI_statusReg.lastTransOK );
}

// ********** Interrupt Handlers ********** //
/****************************************************************************
This function is the Interrupt Service Routine (ISR), and called when the TWI interrupt is triggered;
that is whenever a TWI event has occurred. This function should not be called directly from the main
application.
****************************************************************************/
#pragma vector=TWI_vect
__interrupt void TWI_ISR( void )
{
static unsigned char TWI_bufPtr;

switch (TWSR)
{
  case TWI_STX_ADR_ACK:       // Own SLA+R has been received; ACK has been returned
// case TWI_STX_ADR_ACK_M_ARB_LOST: // Arbitration lost in SLA+R/W as Master; own SLA+R has been received; ACK has been returned
TWI_bufPtr = 0;                      // Set buffer pointer to first data location
  case TWI_STX_DATA_ACK:    // Data byte in TWDR has been transmitted; ACK has been received
TWDR = TWI_buf[TWI_bufPtr++];
TWCR = (1<<TWEN)|                      // TWI Interface enabled
      (1<<TWIE)|(1<<TWINT)|             // Enable TWI Interupt and clear the flag to send byte
      (1<<TWEA)|(0<<TWSTA)|(0<<TWSTO)|    //
      (0<<TWWC);                      //
TWI_busy = 1;
break;
  case TWI_STX_DATA_NACK:    // Data byte in TWDR has been transmitted; NACK has been received.
                     // I.e. this could be the end of the transmission.
if (TWI_bufPtr == TWI_msgSize) // Have we transceived all expected data?
{
TWI_statusReg.lastTransOK = TRUE;          // Set status bits to completed successfully.
}
else                // Master has sent a NACK before all data where sent.
{
TWI_state = TWSR;                   // Store TWI State as errormessage.
}

TWCR = (1<<TWEN)|                      // Enable TWI-interface and release TWI pins
      (1<<TWIE)|(1<<TWINT)|             // Keep interrupt enabled and clear the flag
      (1<<TWEA)|(0<<TWSTA)|(0<<TWSTO)|    // Answer on next address match
      (0<<TWWC);                      //

TWI_busy = 0; // Transmit is finished, we are not busy anymore
break;
  case TWI_SRX_GEN_ACK:       // General call address has been received; ACK has been returned
// case TWI_SRX_GEN_ACK_M_ARB_LOST: // Arbitration lost in SLA+R/W as Master; General call address has been received; ACK has been returned
TWI_statusReg.genAddressCall = TRUE;
  case TWI_SRX_ADR_ACK:       // Own SLA+W has been received ACK has been returned
// case TWI_SRX_ADR_ACK_M_ARB_LOST: // Arbitration lost in SLA+R/W as Master; own SLA+W has been received; ACK has been returned
                                 // Dont need to clear TWI_S_statusRegister.generalAddressCall due to that it is the default state.
TWI_statusReg.RxDataInBuf = TRUE;
TWI_bufPtr = 0;                      // Set buffer pointer to first data location

                                 // Reset the TWI Interupt to wait for a new event.
TWCR = (1<<TWEN)|                      // TWI Interface enabled
      (1<<TWIE)|(1<<TWINT)|             // Enable TWI Interupt and clear the flag to send byte
      (1<<TWEA)|(0<<TWSTA)|(0<<TWSTO)|    // Expect ACK on this transmission
      (0<<TWWC);
TWI_busy = 1;

break;
  case TWI_SRX_ADR_DATA_ACK:    // Previously addressed with own SLA+W; data has been received; ACK has been returned
  case TWI_SRX_GEN_DATA_ACK:    // Previously addressed with general call; data has been received; ACK has been returned
TWI_buf[TWI_bufPtr++] = TWDR;
TWI_statusReg.lastTransOK = TRUE;          // Set flag transmission successfull.
                                 // Reset the TWI Interupt to wait for a new event.
TWCR = (1<<TWEN)|                      // TWI Interface enabled
      (1<<TWIE)|(1<<TWINT)|             // Enable TWI Interupt and clear the flag to send byte
      (1<<TWEA)|(0<<TWSTA)|(0<<TWSTO)|    // Send ACK after next reception
      (0<<TWWC);                      //
TWI_busy = 1;
break;
  case TWI_SRX_STOP_RESTART:    // A STOP condition or repeated START condition has been received while still addressed as Slave
                                 // Enter not addressed mode and listen to address match
TWCR = (1<<TWEN)|                      // Enable TWI-interface and release TWI pins
      (1<<TWIE)|(1<<TWINT)|             // Enable interrupt and clear the flag
      (1<<TWEA)|(0<<TWSTA)|(0<<TWSTO)|    // Wait for new address match
      (0<<TWWC);                      //

TWI_busy = 0; // We are waiting for a new address match, so we are not busy

break;
  case TWI_SRX_ADR_DATA_NACK:    // Previously addressed with own SLA+W; data has been received; NOT ACK has been returned
  case TWI_SRX_GEN_DATA_NACK:    // Previously addressed with general call; data has been received; NOT ACK has been returned
  case TWI_STX_DATA_ACK_LAST_BYTE: // Last data byte in TWDR has been transmitted (TWEA = ??; ACK has been received
// case TWI_NO_STATE       // No relevant state information available; TWINT = ??
  case TWI_BUS_ERROR:    // Bus error due to an illegal START or STOP condition
TWI_state = TWSR;          //Store TWI State as errormessage, operation also clears noErrors bit
TWCR = (1<<TWSTO)|(1<<TWINT); //Recover from TWI_BUS_ERROR, this will release the SDA and SCL pins thus enabling other devices to use the bus
break;
  default:
TWI_state = TWSR;                      // Store TWI State as errormessage, operation also clears the Success bit.
TWCR = (1<<TWEN)|                      // Enable TWI-interface and release TWI pins
      (1<<TWIE)|(1<<TWINT)|             // Keep interrupt enabled and clear the flag
      (1<<TWEA)|(0<<TWSTA)|(0<<TWSTO)|    // Acknowledge on any new requests.
      (0<<TWWC);                      //

TWI_busy = 0; // Unknown status, so we wait for a new address match that might be something we can handle
}
}

//***********************
//slave.h
//***********************

/****************************************************************************
TWI Status/Control register definitions
****************************************************************************/

#define TWI_BUFFER_SIZE 4    // Reserves memory for the drivers transceiver buffer.
                  // Set this to the largest message size that will be sent including address byte.

/****************************************************************************
Global definitions
****************************************************************************/

union TWI_statusReg_t             // Status byte holding flags.
{
  unsigned char all;
  struct
  {
unsigned char lastTransOK:1;
unsigned char RxDataInBuf:1;
unsigned char genAddressCall:1;                // TRUE = General call, FALSE = TWI Address;
unsigned char unusedBits:5;
  };
};

extern union TWI_statusReg_t TWI_statusReg;

static unsigned char dont_sleep = 0;

只看该作者 · 2009-11-30 22:32

/****************************************************************************
Function definitions
****************************************************************************/
void TWI_Slave_Initialise( unsigned char );
unsigned char TWI_Transceiver_Busy( void );
unsigned char TWI_Get_State_Info( void );
void TWI_Start_Transceiver_With_Data( unsigned char * , unsigned char );
void TWI_Start_Transceiver( void );
unsigned char TWI_Get_Data_From_Transceiver( unsigned char *, unsigned char );

#pragma vector=TWI_vect
__interrupt void TWI_ISR( void );

/****************************************************************************
Bit and byte definitions
****************************************************************************/
#define TWI_READ_BIT 0 // Bit position for R/W bit in "address byte".
#define TWI_ADR_BITS 1 // Bit position for LSB of the slave address bits in the init byte.
#define TWI_GEN_BIT 0 // Bit position for LSB of the general call bit in the init byte.

#define TRUE    1
#define FALSE    0

/****************************************************************************
TWI State codes
****************************************************************************/
// General TWI Master staus codes
#define TWI_START          0x08 // START has been transmitted
#define TWI_REP_START       0x10 // Repeated START has been transmitted
#define TWI_ARB_LOST          0x38 // Arbitration lost

// TWI Master Transmitter staus codes
#define TWI_MTX_ADR_ACK       0x18 // SLA+W has been tramsmitted and ACK received
#define TWI_MTX_ADR_NACK    0x20 // SLA+W has been tramsmitted and NACK received
#define TWI_MTX_DATA_ACK    0x28 // Data byte has been tramsmitted and ACK received
#define TWI_MTX_DATA_NACK    0x30 // Data byte has been tramsmitted and NACK received

// TWI Master Receiver staus codes
#define TWI_MRX_ADR_ACK       0x40 // SLA+R has been tramsmitted and ACK received
#define TWI_MRX_ADR_NACK    0x48 // SLA+R has been tramsmitted and NACK received
#define TWI_MRX_DATA_ACK    0x50 // Data byte has been received and ACK tramsmitted
#define TWI_MRX_DATA_NACK    0x58 // Data byte has been received and NACK tramsmitted

// TWI Slave Transmitter staus codes
#define TWI_STX_ADR_ACK       0xA8 // Own SLA+R has been received; ACK has been returned
#define TWI_STX_ADR_ACK_M_ARB_LOST 0xB0 // Arbitration lost in SLA+R/W as Master; own SLA+R has been received; ACK has been returned
#define TWI_STX_DATA_ACK    0xB8 // Data byte in TWDR has been transmitted; ACK has been received
#define TWI_STX_DATA_NACK    0xC0 // Data byte in TWDR has been transmitted; NOT ACK has been received
#define TWI_STX_DATA_ACK_LAST_BYTE 0xC8 // Last data byte in TWDR has been transmitted (TWEA = ??; ACK has been received

// TWI Slave Receiver staus codes
#define TWI_SRX_ADR_ACK       0x60 // Own SLA+W has been received ACK has been returned
#define TWI_SRX_ADR_ACK_M_ARB_LOST 0x68 // Arbitration lost in SLA+R/W as Master; own SLA+W has been received; ACK has been returned
#define TWI_SRX_GEN_ACK       0x70 // General call address has been received; ACK has been returned
#define TWI_SRX_GEN_ACK_M_ARB_LOST 0x78 // Arbitration lost in SLA+R/W as Master; General call address has been received; ACK has been returned
#define TWI_SRX_ADR_DATA_ACK    0x80 // Previously addressed with own SLA+W; data has been received; ACK has been returned
#define TWI_SRX_ADR_DATA_NACK    0x88 // Previously addressed with own SLA+W; data has been received; NOT ACK has been returned
#define TWI_SRX_GEN_DATA_ACK    0x90 // Previously addressed with general call; data has been received; ACK has been returned
#define TWI_SRX_GEN_DATA_NACK    0x98 // Previously addressed with general call; data has been received; NOT ACK has been returned
#define TWI_SRX_STOP_RESTART    0xA0 // A STOP condition or repeated START condition has been received while still addressed as Slave

// TWI Miscellaneous status codes
#define TWI_NO_STATE          0xF8 // No relevant state information available; TWINT = ??
#define TWI_BUS_ERROR       0x00 // Bus error due to an illegal START or STOP condition