Отправлено Sdl 18 июля 2003 г. 11:35 В ответ на: Помогите разобраться сTWI в ATMega8, с передачей всё ясно, а как принять байт не врублюсь, примерчик бы... отправлено Барсук 17 июля 2003 г. 17:01

// state machine 
// ff  - error bus
// 7f  - OK
#define SLA_W               0x00
#define SLA_R               0x01
#define START_I2C          ( ( 1 << TWINT) | ( 1 << TWSTA) | ( 1 << TWEN)| ( 1<< TWIE) ) 
#define STOP_I2C           ( ( 1 << TWINT) | ( 1 << TWSTO) | ( 1 << TWEN) )
#define OUT_BYTE_I2C       ( ( 1 << TWINT) | ( 1 << TWEN)  | ( 1 << TWIE) )
#define IN_BYTE_I2C_ACK    ( ( 1 << TWINT) | ( 1 << TWEN)  | ( 1 << TWEA) | ( 1 << TWIE) )
#define IN_BYTE_I2C_NACK   ( ( 1 << TWINT) | ( 1 << TWEN)  | ( 1 << TWIE) )
// if rd_wr = 0  - write
void init_i2c_int( uchar rd_wr, uchar adr_chip, uchar adr_mem, uchar count_byte, uchar *buf)
{
  clr_bit_reg( DDRC, PC4);
  clr_bit_reg( DDRC, PC5);
  
  clr_bit_reg( PORTC, PC4);
  clr_bit_reg( PORTC, PC5);
  
  
  TWAR = 0x00;       
  TWBR = 100;  // 97 kHz
  TWSR = 0x00;  
  adr_chip_i2c = adr_chip;
  adr_mem_i2c  = adr_mem;
  len_i2c    = count_byte; 
  ptr_i2c = buf;
  direct_i2c_rd = rd_wr; // !0 - read
  state_i2c = 1;
  
// START 
  _SEI();           //       global interrupt enable
  TWCR = START_I2C; 
}
// EXIT 0 - OK
uchar   wait_i2c(void)
{
  while(1) {
  if( state_i2c == 0x00 )   return( 0);  
  if( state_i2c == 0x7f )   return( 0x7f);  
  if( state_i2c == 0xFF )   return( 0xff);  
  } // while
}
#pragma vector=  TWI_vect
 __interrupt void interrupt_i2c( void)
{
  uchar c;
  c = TWSR;
//  rs_out_232( state_i2c);
  // 0   -  start i2c bus call from main program (init_i2c_interrupt)
  switch( state_i2c) {  
  case 1:   // write byte  adr_chip cmd SLA+W
           if( !((c == 0x08) || (c == 0x10))) break;  // not start
           TWDR = adr_chip_i2c | SLA_W;     
           TWCR = OUT_BYTE_I2C; 
           state_i2c++;
           return;
  case 2:  // write adr_mem
           if( c != 0x18 ) break;                  // not write adr_chip
           TWDR = adr_mem_i2c;
           TWCR = OUT_BYTE_I2C;
           state_i2c++;
           return;
  case 3:  // write bytes data if write ops
           if( c != 0x28 ) break;                  // not write adr_chip
           if( direct_i2c_rd ){ 
                                // stop                                  
                                TWCR = STOP_I2C; 
                                state_i2c++;
                                while( ( get_bit_reg( TWCR, TWSTO)));  // wait stop
                                TWCR = START_I2C;                      // start for read
                                return;
                               }  
           if ( !len_i2c ) {
                                // stop, end interrupt
                                TWCR      = STOP_I2C;  
                                state_i2c = 0x00;                      // OK
                                while( ( get_bit_reg( TWCR, TWSTO)));  // wait stop  
                                TWCR = (1 << TWINT);                   // end write
                                return;
                               }              
           TWDR = *ptr_i2c;         
           TWCR = OUT_BYTE_I2C;
           len_i2c--;
           ptr_i2c++;  
           return;
  case 4:
           if( !((c == 0x08) || (c == 0x10))) break;  
           TWDR = adr_chip_i2c | SLA_R;     
           TWCR = OUT_BYTE_I2C;
           state_i2c++;
           return;
  case 5:  
           if( c != 0x40 ) break;                  
           if ( !len_i2c )  
                              {
                                // stop, end interrupt
                                TWCR      = STOP_I2C;  
                                state_i2c = 0x00;                       // OK
                                while( ( get_bit_reg( TWCR, TWSTO)));  // wait stop  
                                TWCR = (1 << TWINT);                   // end read
                                return;
                               }
           if ( len_i2c == 1) 
                              {
                                TWCR = IN_BYTE_I2C_NACK;
                                state_i2c+=2;
                              }
                      else
                              {
                                TWCR = IN_BYTE_I2C_ACK; 
                                state_i2c++;
                              }
           return;
  case 6:           
           if( (c != 0x50) ) break;                  
           *ptr_i2c = TWDR;                   
           len_i2c--;
           ptr_i2c++;  
           if ( len_i2c == 1) 
                              {
                                TWCR = IN_BYTE_I2C_NACK;
                                state_i2c++;
                              }
                      else
                              {
                                TWCR = IN_BYTE_I2C_ACK; 
                              }
           return;
  case 7:           
           if( (c != 0x58) ) break;                  
           *ptr_i2c = TWDR;                   
           TWCR      = STOP_I2C;  
           state_i2c = 0x00;
           while( ( get_bit_reg( TWCR, TWSTO)));  // wait stop  
           TWCR = (1 << TWINT);                   // end read
           return;
    default:
           TWCR = (1 << TWINT);
           state_i2c = 0x7f;
           return;
    } //switch ( state_i2c)
    TWCR = (1 << TWINT);
    state_TWSR = c;
    state_i2c = 0xff;
}
#pragma function=default