hd7279a的控制
hd7279a是一个按键和数码管驱动芯片，具体参数百度上可查。我用arduino nano控制，可以控制四位数码管显示，但是按键却总是不工作，并且KEY端子一直显示是0（表示有按键），但是读取得键值却是FF（表示没有键值），相互矛盾，希望了解的朋友提供帮助。下面是测试程序。#define CMD_RESET 0xa4
#define CMD_TEST 0xbf
#define DECODE0 0x80
#define DECODE1 0xc8
#define CMD_READ 0x15
#define UNDECODE 0x90
#define RTL_CYCLE 0xa3
#define RTR_CYCLE 0xa2
#define RTL_UNCYL 0xa1
#define RTR_UNCYL 0xa0
#define ACTCTL 0x98
#define SEGON 0xe0
#define SEGOFF 0xc0
#define BLINKCTL 0x88
int pbIn = 1;
int key1=0;
int dat=10;
int key=3;
int cs=12;
int clk=11;
int num0=9;
void setup() {
pinMode(dat,OUTPUT);
pinMode(cs,OUTPUT);
pinMode(clk,OUTPUT);
pinMode(key,OUTPUT);
Serial.begin(9600);
send_byte(CMD_TEST);
Serial.println(pbIn);
delay(1000);
send_byte(CMD_RESET);
}
void loop() {
write7279(DECODE1,key);
write7279(DECODE1+1,key1);
write7279(DECODE1+2,pbIn);
write7279(DECODE1+3,num0);
pbIn=digitalRead(key);
Serial.println(pbIn);
Serial.println(key1);
key1=read7279(CMD_READ);
delay(1000);
}
void write7279(unsigned char cmd, unsigned char dta)
{
send_byte (cmd);
send_byte (dta);
}
unsigned char read7279(unsigned char command)
{
send_byte(command);
return(receive_byte());
}
void send_byte( unsigned char out_byte)
{
unsigned char i;
digitalWrite(cs, LOW);
delayMicroseconds(50);
for (i=0;i<8;i++)
{
if (out_byte&0x80)
{
digitalWrite(dat, HIGH);
}
else
{
digitalWrite(dat, LOW);
}
digitalWrite(clk, HIGH);
delayMicroseconds(1);
digitalWrite(clk, LOW);
delayMicroseconds(1);
out_byte=out_byte*2;
}
digitalWrite(dat, LOW);
}
unsigned char receive_byte(void)
{
unsigned char i, in_byte;
digitalWrite(dat, HIGH);
delayMicroseconds(50);
for (i=0;i<8;i++)
{
digitalWrite(clk, LOW);
delayMicroseconds(1);
in_byte=in_byte*2;
if (digitalRead(dat))
{
in_byte=in_byte|0x01;
}
digitalWrite(clk, LOW);
delayMicroseconds(1);
}
digitalWrite(dat, HIGH);
return (in_byte);
}
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