I bought a 4 Digit 7 Segment serial led module with 2 x TM74HC595 shift registers.
I have the data sheet and some sample code.
I am able to get the sample code to display - which is simply the digits in the void loop.
The connections are 3 wires as listed in the code plus power.
I am trying to understand the meaning/limitations of first 3 lines of the code, which appears to be written in hex format and which I thought would determine the scope of what could be displayed.
However, the second line does not appear to correlate with the third line - so I am a bit lost.
For example I figure 0xC0 (hex) to represent 192 (decimal) - or have I got the wrong end of the stick?
-
An explanation of what line 3 represents would be appreciated.
-
How would I display a decimal point - lets say I wanted to display 999.5?
unsigned char LED_0F[] =
{// 0 1 2 3 4 5 6 7 8 9 A b C d E F -
0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90,0x8C,0xBF,0xC6,0xA1,0x86,0xFF,0xbf
};
unsigned char LED[4]; //用于LED的4位显示缓存
int SCLK = 5;
int RCLK = 6;
int DIO = 7; //这里定义了那三个脚
void setup ()
{
pinMode(SCLK,OUTPUT);
pinMode(RCLK,OUTPUT);
pinMode(DIO,OUTPUT); //让三个脚都是输出状态
}
void loop()
{
LED[0]=3;
LED[1]=2;
LED[2]=1;
LED[3]=0;
while(1)
{
LED4_Display ();
}
}
void LED4_Display (void)
{
unsigned char *led_table; // 查表指针
unsigned char i;
//显示第1位 - Digit 1
led_table = LED_0F + LED[0];
i = *led_table;
LED_OUT(i);
LED_OUT(0x01);
digitalWrite(RCLK,LOW);
digitalWrite(RCLK,HIGH);
//显示第2位 - Digit 2
led_table = LED_0F + LED[1];
i = *led_table;
LED_OUT(i);
LED_OUT(0x02);
digitalWrite(RCLK,LOW);
digitalWrite(RCLK,HIGH);
//显示第3位 - Digit 3
led_table = LED_0F + LED[2];
i = *led_table;
LED_OUT(i);
LED_OUT(0x04);
digitalWrite(RCLK,LOW);
digitalWrite(RCLK,HIGH);
//显示第4位 - Digit 4
led_table = LED_0F + LED[3];
i = *led_table;
LED_OUT(i);
LED_OUT(0x08);
digitalWrite(RCLK,LOW);
digitalWrite(RCLK,HIGH);
}
void LED_OUT(unsigned char X)
{
unsigned char i;
for(i=8;i>=1;i--)
{
if (X&0x80)
{
digitalWrite(DIO,HIGH);
}
else
{
digitalWrite(DIO,LOW);
}
X<<=1;
digitalWrite(SCLK,LOW);
digitalWrite(SCLK,HIGH);
}
}
4x7_led_data.pdf (33.3 KB)
