IIC通讯IO模拟程序

ti

#define write_com  0x40//输出模式地址
#define read_com 0x41//输入模式地址
#define KeyPort  pcf8574_read_key_board()//key_board PCF8574 read byte
***it sw_one = P5^0;//menu keypad
***it sw_data = P5^1;//IIC data bus
***it sw_clk = P2^5;//IIC clk bus
***it sw_int = P2^6;//IIC interrput bus
//key_board IC driver init
void setup_key_board(void)
{
P5M1 |= 0x01;
P5M0 |= 0x00;//P5.0(sw_one)为仅为输入；P5.1(sw_data)为双向IO

P2M1 |= 0x40;
P2M0 |= 0x20;//P2.5(CLK)为推挽输出；P2.6(interrupt)为输入
}
//start condition
void iic_start_condition(void)
{
sw_clk = 1;//clk high level
sw_data = 1;//data high level
delay_5us(8);//delay 10us
sw_data = 0;//data low level
delay_5us(4);//delay 10us
}
//stop condition
void iic_stop_condition(void)
{
delay_5us(4);//delay 10us
sw_clk = 1;//clk high level
delay_5us(4);//delay 10us
sw_data = 0;//data high level
delay_5us(4);//delay 10us
sw_data = 1;//data low level
}
//master send acknowlege
void iic_send_acknowlege(unsigned char ack)
{
sw_data = ack;//send ack bit

sw_clk = 1;//clk high level
delay_5us(1);//delay 10us
sw_clk = 0;//clk low level
delay_5us(1);//delay 10us
}
//master receive acknowlege
unsigned char iic_receive_acknowlege(void)
{
unsigned char ack;
sw_clk = 0;//clk low level
delay_5us(8);//delay 10us
sw_clk = 1;//clk high level
ack = sw_data ;//receive ack from slave
delay_5us(4);//delay 10us
sw_clk = 0;//clk low level

return ack;//return ack bit
}
//key_board IC bus write
void iic_write_key_board(unsigned char date)
{
unsigned char i;
for(i=0;i<8;i++)
{
  sw_clk = 0;//clk low level
  delay_5us(4);//delay 10us
  if(date&0x80)
  {
sw_data=1;
  }
  else
  {
sw_data=0;
  }
  date<<=1;
  delay_5us(4);//delay 10us
  sw_clk = 1;//clk high level
  delay_5us(4);//delay 10us
}
iic_receive_acknowlege();//receive ack bit from slave
}

//key_board IIC bus read
unsigned char iic_read_key_board(void)
{
unsigned char i,date=0;

//sw_data = 1;//data high level
for(i=0;i<8;i++)
{
  date <<= 1;
  sw_clk = 0;//clk low level
  delay_5us(4);//delay 10us
  date |= sw_data;//read port state

  delay_5us(4);//delay 10us
  sw_clk = 1;//clk high level
  delay_5us(4);//delay 10us
}
iic_receive_acknowlege();//receive ack bit from slave
return date;
}
//key_board PCF8574 write byte
void pcf8574_write_key_board(unsigned char date)
{
//start condition
iic_start_condition();
//key_board IC bus write
iic_write_key_board(write_com);//output model,address
iic_write_key_board(date);//output model,date
}
//key_board PCF8574 read byte
unsigned char pcf8574_read_key_board(void)
{
unsigned char temp_date;
//start condition
iic_start_condition();
//key_board IC bus write
iic_write_key_board(read_com);//input model,address
temp_date = iic_read_key_board();
//stop condition
iic_stop_condition();
delay_5us(1);//delay 10us
return temp_date;
}