IIC Sample Code
#include <reg52.h>
#include <math.h>
#define DELAY_TIME 600
#define TRUE 1
#define FALSE 0
#define uchar unsigned char
#define uint unsigned int
//————–define IIC SCL,SDA port——————————
sbit SCL = P1 ^ 7;
sbit SDA = P1 ^ 6;
//—————–define Max7219 port—————————
sbit Max7219_pinCLK = P2 ^ 2;
sbit Max7219_pinCS = P2 ^ 1;
sbit Max7219_pinDIN = P2 ^ 0;
//————-delay time_us——————————-
void DELAY(uint t)
{
while (t != 0)
t–;
}
//————-IIC START CONDITION——————————-
void I2C_Start(void)
{
SDA = 1; //SDA output high
DELAY(DELAY_TIME);
SCL = 1;
DELAY(DELAY_TIME); //SCL output high
SDA = 0;
DELAY(DELAY_TIME);
SCL = 0;
DELAY(DELAY_TIME);
}
//————-IIC STOP CONDITION——————————-
void I2C_Stop(void)
{
SDA = 0; //SDA OUTPUT LOW
DELAY(DELAY_TIME);
SCL = 1;
DELAY(DELAY_TIME);
SDA = 1;
DELAY(DELAY_TIME);
SCL = 0; //SCL OUTPUT LOW
DELAY(DELAY_TIME);
}
//————-IIC SEND DATA “0”——————————-
void SEND_0(void)
{
SDA = 0;
DELAY(DELAY_TIME);
SCL = 1;
DELAY(DELAY_TIME);
SCL = 0;
DELAY(DELAY_TIME);
}
//————-IIC SEND DATA “1”——————————-
void SEND_1(void)
{
SDA = 1;
DELAY(DELAY_TIME);
SCL = 1;
DELAY(DELAY_TIME);
SCL = 0;
DELAY(DELAY_TIME);
}
//————-Check SLAVE’s Acknowledge ——————————-
bit Check_Acknowledge(void)
{
SDA = 1;
DELAY(DELAY_TIME);
SCL = 1;
DELAY(DELAY_TIME / 2);
F0 = SDA;
DELAY(DELAY_TIME / 2);
SCL = 0;
DELAY(DELAY_TIME);
if (F0 == 1)
return FALSE;
return TRUE;
}
//————-Write One Byte of Data ——————————-
void WriteI2CByte(uchar b) reentrant
{
char i;
for (i = 0; i < 8; i++)
if ((b << i) & 0x80)
SEND_1();
else
SEND_0();
}
//————-Read One Byte of Data ——————————-
uchar ReadI2CByte(void) reentrant
{
char b = 0, i;
for (i = 0; i < 8; i++)
{
SDA = 1;
DELAY(DELAY_TIME);
SCL = 1;
DELAY(DELAY_TIME);
//DELAY(10);
F0 = SDA;
DELAY(DELAY_TIME);
//DELAY(10);
SCL = 0;
if (F0 == 1)
{
b = b << 1;
b = b | 0x01;
}
else
b = b << 1;
}
return b;
}
//————-write One Byte of Data,Data from MASTER to the SLAVER ——————————-
//————-SLAVER address bit:01101101——————————-
void Write_One_Byte(uchar addr, uchar thedata) //Write “thedata” to the SLAVER’s address of “addr”
{
bit acktemp = 1;
I2C_Start(); //IIC START
WriteI2CByte(0xDA); //IIC WRITE operation,SLAVER address bit:01101010
acktemp = Check_Acknowledge(); //check the SLAVER
WriteI2CByte(addr); /*address*/
acktemp = Check_Acknowledge();
WriteI2CByte(thedata); /*thedata*/
acktemp = Check_Acknowledge();
I2C_Stop(); //IIC STOP
}
//————-Reaed One Byte of Data,Data from SLAVER to the MASTER ——————————-
uchar Read_One_Byte(uchar addr)
{
bit acktemp = 1;
uchar mydata;
I2C_Start();
WriteI2CByte(0xDA);
acktemp = Check_Acknowledge();
WriteI2CByte(addr);
acktemp = Check_Acknowledge();
I2C_Start();
WriteI2CByte(0xDB); //IIC READ operation
acktemp = Check_Acknowledge();
mydata = ReadI2CByte();
acktemp = Check_Acknowledge();
I2C_Stop();
return mydata;
}
//————-Delay_ms ——————————-
void Delay_xms(uint x)
{
uint i, j;
for (i = 0; i < x; i++)
for (j = 0; j < 112; j++)
;
}
//————-Write One Byte to the Max7219————-
void Write_Max7219_byte(uchar DATA)
{
uchar i;
Max7219_pinCS = 0; //CS low effect
for (i = 8; i >= 1; i–)
{
Max7219_pinCLK = 0;
Max7219_pinDIN = DATA & 0x80;
DATA = DATA << 1;
Max7219_pinCLK = 1; //when pinCLK is high send the Data
}
}
//————-decide which address shows the Data————-
void Write_Max7219(uchar address,uchar dat)
{
Max7219_pinCS = 0;
Write_Max7219_byte(address);
Write_Max7219_byte(dat);
Max7219_pinCS = 1;
}
//————-MAX_7219 Initialization————-
void Init_MAX7219(void)
{
Write_Max7219(0x09, 0xff); //Decoded mode：BCD code
Write_Max7219(0x0a, 0x03); //Brightness
Write_Max7219(0x0b, 0x07); //Scan limit：8 digital display
Write_Max7219(0x0c, 0x01); //Power-Down modes ：0，Normal code：1
Write_Max7219(0x0f, 0x01); //Display test：1；Test end，normal display：0
}
void main(void)
{
uchar yali1, yali2, yali3,wendu1,wendu2;
uchar temp_a5;
long int ad,temp;
long float pas;
uchar dis[8];
Init_MAX7219();
Delay_xms(1000);
Write_Max7219(0x0f, 0x00);
while (1)
{
temp_a5 = Read_One_Byte(0xA5);//Read ASIC Sys_config
temp_a5 = temp_a5 & 0xFD; //（Raw_data_on: 0: output calibrated data，namly the value in 0x06-0x0a）
Write_One_Byte(0xA5, temp_a5); //Set ADC output calibrated Data
Write_One_Byte(0x30, 0x0A); //indicate a combined conversion (once temperature conversion immediately followed by once sensor signal conversion)（wire measure order in 0x30，000：single temp. measure；001：single pressure. measure；010：combination：single pressure and temp. measurement；011：sleep mode（combined mode measurement at certain time intervals））
while ((Read_One_Byte(0x30) & 0x08) > 0); //Judge whether Data collection is over
// ————-READ ADC output Data of Pressure ————-
yali1 = Read_One_Byte(0x06);
yali2 = Read_One_Byte(0x07);
yali3 = Read_One_Byte(0x08);
ad = yali1 * 65536 + yali2 * 256 + yali3;
// ————-READ ADC output Data of Temperature ————-
wendu1= Read_One_Byte(0x09);
wendu2= Read_One_Byte(0x0a);
temp=wendu1*256+wendu2;
/*Conversion, the following is the conversion formula of 100*/
if (ad > 8388608) // >8388606 as negative value, handle at display end
{
pas = (ad – 16777216)/64/1000; //unit is kpa
}
else
{
pas = ad/64/1000; //unit is kpa
}
if (pas < 0)
pas = fabs(pas);
/*Display program with Max7219*/
dis[0] = (long int)pas / 10000000;
dis[1] = (long int)pas % 10000000 / 1000000;
dis[2] = (long int)pas % 1000000 / 100000;
dis[3] = (long int)pas % 100000 / 10000;
dis[4] = (long int)pas % 10000 / 1000;
dis[5] = (long int)pas % 1000 / 100;
dis[6] = (long int)pas % 100 / 10;
dis[7] = (long int)pas % 10;
Write_Max7219(8, dis[0]);
Write_Max7219(7, dis[1]);
Write_Max7219(6, dis[2]);
Write_Max7219(5, dis[3]);
Write_Max7219(4, dis[4]);
Write_Max7219(3, dis[5]);
Write_Max7219(2, dis[6]);
Write_Max7219(1, dis[7]);
Delay_xms(100); //delay 100ms
}
}