蓝桥杯之单片机学习(十九)——IIC协议(PCF8591、AT24C02)
一、EEPROM、AD/DA电路
AD/DA电路:光敏电阻、电压分压
EEOROM:保存数据——数据写进和读出
二、IIC协议介绍
三、PCF8591、AT24C02编程
3.1 PCF8591
先写在读
- 告诉ADC读哪个通道
- 然后接收回来
3.2 AT24C02
四、练习
- 编程实现PCF8591读取通道1和通道3的电压值:
- 编程实现AT24C02的读写, 让0x55单元的数值每次上电自加1。
五、代码展示
#include "reg52.h"
#include "intrins.h"
#include "iic.h"
typedef unsigned char BYTE;
typedef unsigned int WORD;
unsigned char adc_table[3];
unsigned char volt_table[3];
unsigned char open_num_table[2];
//-----------------------------------------------
/* define constants */
#define FOSC 11059200L
#define T1MS (65536-FOSC/12/1000) //1ms timer calculation method in 12T mode
/* define SFR */
sbit TEST_LED = P1^0; //work LED, flash once per second
/* define variables */
WORD count; //1000 times counter
//-----------------------------------------------
unsigned char code T_display[]={0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x6F};
unsigned char code T_COM[]={0x01,0x02,0x04,0x08,0x10,0x20,0x40,0x80};
/* Timer0 interrupt routine */
void tm0_isr() interrupt 1 using 1
{
static char i;
TL0 = T1MS; //reload timer0 low byte
TH0 = T1MS >> 8; //reload timer0 high byte
if (count-- == 0) //1ms * 1000 -> 1s
{
count = 1; //reset counter
P2=0xe0;P0=~open_num_table[i];P2=0;
P2=0xc0;P0=T_COM[i];P2=0;
i++;
if(i==2) i=0;
}
}
//-----------------------------------------------
void Delay2ms() //@11.0592MHz
{
unsigned char i, j;
_nop_();
i = 4;
j = 146;
do
{
while (--j);
} while (--i);
}
/* main program */
void main()
{
unsigned char adc_val;
unsigned char open_num=0;
float volt;
open_num =read_24c02(0x55);
write_24c02(0x55,++open_num);
open_num_table[0]=T_display[open_num/10];
open_num_table[1]=T_display[open_num%10];
TMOD = 0x01; //set timer0 as mode1 (16-bit)
TL0 = T1MS; //initial timer0 low byte
TH0 = T1MS >> 8; //initial timer0 high byte
TR0 = 1; //timer0 start running
ET0 = 1; //enable timer0 interrupt
EA = 1; //open global interrupt switch
count = 0; //initial counter
write_adc(0x03); // ch3
while(1)
{
EA=0;
adc_val=read_adc(0x03);
EA=1;
volt=adc_val/255.0f*5;
adc_table[0]=adc_val/100;//bai
adc_table[1]=adc_val/10%10;//shi
adc_table[2]=adc_val%10;
volt_table[0]=T_display[(unsigned char)volt] | 0x80;
volt_table[1]=T_display[(unsigned char)(volt*10)%10];
volt_table[2]=T_display[(unsigned char)(volt*100)%10];
Delay2ms();
}
}
一些事项
PCF8591的通道1是光敏电阻,通道3是ADC转换
24C02与EEPROM可以掉电保存