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  1. #include <avr/io.h>
  2.  
  3. #ifndef F_CPU
  4. #define F_CPU 16000000UL
  5. #endif
  6.  
  7. #include <util/delay.h>
  8.  
  9. #define I2C_SDA_DDR  DDRB
  10. #define I2C_SCL_DDR  DDRB
  11. #define I2C_TEST_DDR DDRB
  12.  
  13. #define I2C_SDA_PORT  PORTB
  14. #define I2C_SCL_PORT  PORTB
  15. #define I2C_TEST_PORT PORTB
  16.  
  17. #define I2C_SDA_PIN  PB1
  18. #define I2C_SCL_PIN  PB2
  19. #define I2C_TEST_PIN PB5
  20.  
  21. #define STARTB 0x00 //star bit
  22. #define STOPB  0x01 //stop bit
  23.  
  24. #define setPin(pport, ppin, pbit)         \
  25.       (pport = pbit                       \
  26.                ? pport |  (0x01 << ppin)  \
  27.                : pport & (~(0x01 << ppin)))
  28.  
  29. uint8_t ack;
  30.  
  31. void setStaSto(const uint8_t pStaSto){
  32.    //reset SCL and SDA
  33.    pStaSto                                         \
  34.          ? setPin(I2C_SDA_PORT, I2C_SDA_PIN, 0x01) \
  35.          : setPin(I2C_SDA_PORT, I2C_SDA_PIN, 0x00);
  36.    setPin(I2C_SCL_PORT, I2C_SCL_PIN, 0x00);
  37.  
  38.    //SDA HIGH for StartBit, SDA LOW, for StopBit
  39.    pStaSto
  40.          ? setPin(I2C_SDA_PORT, I2C_SDA_PIN, 0x00)  //begin stop bit
  41.          : setPin(I2C_SDA_PORT, I2C_SDA_PIN, 0x01); //begin start bit
  42.    setPin(I2C_SCL_PORT, I2C_SCL_PIN, 0x01);
  43.    _delay_us(0x01); //7 - tSU:sTA > 600nS
  44.  
  45.    //SDA LOW for StartBit, SDA HIGH for StopBit
  46.    pStaSto
  47.          ? setPin(I2C_SDA_PORT, I2C_SDA_PIN, 0x01)  //end stop bit
  48.          : setPin(I2C_SDA_PORT, I2C_SDA_PIN, 0x00); //end start bit
  49.    _delay_us(0x01); //6 - tHD:sTA > 600nS
  50.  
  51.    //set SCL LOW, end of Start or Stop Conditions
  52.    setPin(I2C_SCL_PORT, I2C_SCL_PIN, 0x00);
  53.    _delay_us(0x02); //3 - tLOW > 1.3uS - maybe it's not needed
  54. }
  55.  
  56. void sendByte(uint8_t pByte){
  57.    uint8_t tmppByte = pByte;
  58.  
  59.    for(uint8_t i = 0x00; i < 0x08; i++){
  60.       //set SCL to LOW to allow Data change
  61.       setPin(I2C_SCL_PORT, I2C_SCL_PIN, 0x00);
  62.       _delay_us(0x01); // 3 - tLOW > 1.3uS - not sure if needed - I set it to the 1sthalf of waht is needed
  63.       setPin(I2C_SDA_PORT, I2C_SDA_PIN, tmppByte >> 0x07); //Get MSB of pByte
  64.       tmppByte <<= 0x01; //Get next bit
  65.       _delay_us(0x01); //3 - tLOW > 1.3 uS - not sure if needed - I set it to the 2nd half of what is needed
  66.       //set SCL to HIGH
  67.       setPin(I2C_SCL_PORT, I2C_SCL_PIN, 0x01);
  68.       _delay_us(0x01); //2 - tHIGH > 600nS
  69.       setPin(I2C_SCL_PORT, I2C_SCL_PIN, 0x00);
  70.       //8 - tHD:DAT > 0 - therefore, not needed
  71.    }
  72.    ack = checkACK();
  73. }
  74.  
  75. uint8_t checkACK(void){
  76.    //set SDA as input to allow SDA reading
  77.    setPin(I2C_SDA_DDR, I2C_SDA_PIN, 0x00);
  78.    //set SDA pin to tri-state mode, disable internal pull-up
  79.    setPin(I2C_SDA_PORT, I2C_SDA_PIN, 0x00);
  80.    //read ACK value
  81.    ack = ( I2C_SDA_PORT & (0x01 << I2C_SDA_PIN) ) \
  82.                   ? 0x01                          \
  83.                   : 0x00;
  84.    //set SDA as output back again
  85.    setPin(I2C_SDA_DDR, I2C_SDA_PIN, 0x01);
  86.    return ack;
  87. }
  88.  
  89. void writeByte(uint8_t pByte){
  90.    setStaSto(STARTB);
  91.    sendByte(0xA0);
  92.    checkACK();
  93.    sendByte(pByte);
  94.    checkACK();
  95.    setStaSto(STOPB);
  96.    checkACK();
  97. }
  98.  
  99. int main(void){
  100.    //one time run code goes here
  101.    //set DDR SDA and SCL pins as output
  102.    setPin(I2C_SDA_DDR, I2C_SDA_PIN, 0x01);
  103.    setPin(I2C_SCL_DDR, I2C_SCL_PIN, 0x01);
  104.    setPin(I2C_TEST_DDR, I2C_TEST_PIN, 0x01);
  105.  
  106.    //loop code goes here
  107.    while(0x01){
  108.       setPin(I2C_TEST_PORT, I2C_TEST_PIN, 0x01);
  109.        _delay_ms(50);
  110.       setPin(I2C_TEST_PORT, I2C_TEST_PIN, 0x00);
  111.       _delay_ms(100);
  112.    }
  113.    return 0;
  114. }
Compilation error #stdin compilation error #stdout 0s 0KB
comments (?)
stdin
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Standard input is empty
compilation info 
prog.c:1:20: fatal error: avr/io.h: No such file or directory
compilation terminated.
stdout
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Standard output is empty
https://ideone.com/VErKsX
language:
C (gcc 8.3)
created:
7 years ago
visibility:
secret

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