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led原理
LED控制代码
LED底层代码一共有两种，一种为状态控制版本，一种为直接赋值法，前者适合状态控制，可以实现每个灯互不影响，后者适合流水灯，PWM灯
//状态控制版本
void led(uchar * LED,uchar pos)
{
static uchar temp=0xff;
if(LED[pos])
temp &= ~(0x01<<pos);
else
temp |= 0x01<<pos;
P0=temp;
hc573(4);
}
void display_task()
{
LED[0] = (col_flag == 0 && display_state1 == 0) ? 1 : 0;
LED[1] = (col_flag == 0 && display_state1 == 1) ? 1 : 0;
LED[2] = (col_flag == 1) ? 1 : 0;
LED[3] = (count_tri >0 && temp > temp_par) ? L4_state : 0;
LED[4] = (count_tri >0 && (hum>90||hum<10)) ? 1 : 0;
LED[5] = (count_tri >= 2) ? L6_state : 0;
LED[6] = 0;
LED[7] = 0;
//直接赋值法
}
void timer1() interrupt 3
{
systick_ms++;
key_dly++;
display_dly++;
collect_dly++;
smg(SMG,dot,pos);
if(++count_200ms == 200)
{
count_200ms = 0;
P0 = 0xff << position; //整体赋值
hc573(4);
if(++position == 9) position = 0;
}
if(++pos == 8) pos = 0;
relay(state_relay);
}LED考点分析
流水灯
以第二届省赛为例
void timer1() interrupt 3
{
systick_ms++;
key_dly++;
display_dly++;
collect_dly++;
smg(SMG,dot,pos);
if(++count_200ms == 200)
{
count_200ms = 0;
P0 = 0xff << position; //整体赋值
hc573(4);
if(mode)
{
if(++position == 9) position = 0;
}
else
{
if(position > 0)
position--;
else
position = 8;
}
}
if(++pos == 8) pos = 0;
relay(state_relay);
}PWM流水灯
以第九届省赛为例 
ledpwm调光的频率大概在100HZ左右，对应时间10ms，题目要求分四个PWM占空比，25%，50%，75%，100%，这样的话需要在2.5ms改变一次LED状态，有点不合理，所以我们将周期改为12ms,频率83HZ。 需要注意的是LED低电平点亮 下面以实现25%亮度为例 
需要在0ms时点亮led，在3ms时熄灭led,加到12ms归零 代码如下（示例)：
uint count_ms;
uint mode_time;
void timer1() interrupt 3
{
systick_ms++;
key_dly++;
display_dly++;
collect_dly++;
smg(SMG,dot,pos);
if(++count_ms == mode_time) //控制移位
{
count_ms = 0;
if(++position == 9)
position = 0;
}
if(pwm_count == 0) //等于0点亮LED
{
P0 = 0xff << position; //整体赋值
hc573(4);
}
else if(pwm_count == pwm_duty) //等于占空比时熄灭
{
P0 = 0xff; //整体赋值
hc573(4);
}
if(++pwm_count == 12) //加到12归零
pwm_count = 0;
if(++pos == 8) pos = 0;
relay(state_relay);
}led闪烁（以x秒为间隔闪烁指的是亮和灭的时间间隔）
题目一 
uint count_ms;
uint mode_time;
void timer1() interrupt 3
{
systick_ms++;
key_dly++;
display_dly++;
collect_dly++;
smg(SMG,dot,pos);
if(++count_ms == mode_time)
{
count_ms = 0;
L1_flag ^= 1;
}
if(++pos == 8) pos = 0;
relay(state_relay);
}
LED[0] = L1_flag;
LED[1] = 0;
LED[2] = 0;
LED[3] = 0;
LED[4] = 0;;
LED[5] = 0;
LED[6] = 0;
LED[7] = 0;题目二 
uint count_ms;
void timer1() interrupt 3
{
systick_ms++;
key_dly++;
display_dly++;
collect_dly++;
smg(SMG,dot,pos);
if(++count_ms == 100)
{
count_ms = 0;
L8_flag ^= 1;
}
if(++pos == 8) pos = 0;
relay(state_relay);
}
LED[0] = 0;
LED[1] = 0;
LED[2] = 0;
LED[3] = 0;
LED[4] = 0;;
LED[5] = 0;
LED[6] = 0;
LED[7] = (mode) ? L8_flag : 0;led亮一定时间后熄灭
题目一 
LED[0] = (Time[1] == 0 && (Time[0] >=0 && Time[0] < 5)) ? 1 : 0;
LED[1] = 0;
LED[2] = 0;
LED[3] = 0;
LED[4] = 0;;
LED[5] = 0;
LED[6] = 0;
LED[7] = 0;题目二 
uint count_ms;
uchar count;
void timer1() interrupt 3
{
systick_ms++;
key_dly++;
display_dly++;
collect_dly++;
smg(SMG,dot,pos);
if(state == 1)
{
if(++count_ms == 200)
{
count_ms = 0;
if(++count == 20)//亮灭各十次
{
count = 0;
state = 0;
}
}
}
if(++pos == 8) pos = 0;
relay(state_relay);
}
LED[0] = (state == 1) ? count % 2 : 0;
LED[1] = 0;
LED[2] = 0;
LED[3] = 0;
LED[4] = 0;;
LED[5] = 0;
LED[6] = 0;
LED[7] = 0;状态指示灯
LED[0] = (vol > vol_old) ? 1 : 0;
LED[1] = (fre > fre_old) ? 1 : 0;
LED[2] = (state_display == 0) ? 1 : 0;
LED[3] = (state_display == 1) ? 1 : 0;
LED[4] = (state_display == 2) ? 1 : 0;
LED[5] = 0;
LED[6] = 0;
LED[7] = 0;二进制灯
用程序员计算器计算发现80的二进制为01010000；与LED的显示正好相反，所以需要进行取反
void timer1() interrupt 3
{
systick_ms++;
key_dly++;
display_dly++;
collect_dly++;
smg(SMG,dot,pos);
P0 = ~(distance);
hc573(4);
if(++pos == 8) pos = 0;
relay(state_relay);
}
