70 lines
2.5 KiB
C
70 lines
2.5 KiB
C
// test4.c
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// 写一个从999999开始倒计时的秒表。并且改用定时器T1的中断来完成
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// make a stopwatch that counts down from 999999. and use interrupt to finish it.
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#include "homework5.h"
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unsigned char LedBuff[6] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF}; // buffer to store the seg chars.
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volatile unsigned char i = 0; // to current digit.
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volatile unsigned long display_time = 999999; // to store the time to display.
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unsigned int cnt = 0; // to count interrupt.
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// init timer
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void initTimer(void)
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{
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TMOD &= 0x0F; // clear TMOD.
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TMOD |= 0x10; // set TMOD to mode 1.
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TH1 = 0xFC; // 1ms timer.
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TL1 = 0x18;
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ET1 = 1; // enable timer 1 interrupt.
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EA = 1; // enable global interrupt.
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TR1 = 1; // start timer 1.
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}
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// timer1 interrupt service routine.
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void timer1ISR(void) interrupt 3
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{
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TH1 = 0xFC; // reset timer.
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TL1 = 0x18;
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// display the number.
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set38Transistors(i);
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P2 = LedBuff[i];
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i = (i + 1) % 6; // to switch to the next digit.
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// 1s timer.
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if (++cnt >= 1000) { // if reached 1s.
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cnt = 0;
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if (display_time > 0) {
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display_time--; // decrease the time.
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}
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}
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}
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void test4()
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{
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initTimer();
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while (1) {
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// split the time into 6 digits.
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unsigned char first_digit = display_time / 100000; // to get the first digit.
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unsigned char second_digit = (display_time % 100000) / 10000; // to get the second digit.
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unsigned char third_digit = (display_time % 10000) / 1000; // to get the third digit.
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unsigned char fourth_digit = (display_time % 1000) / 100; // to get the fourth digit.
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unsigned char fifth_digit = (display_time % 100) / 10; // to get the fifth digit.
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unsigned char sixth_digit = display_time % 10; // to get the sixth digit.
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// load the number in the buffer.
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// 5 is high digit.
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// 0 is low digit.
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LedBuff[5] = LedChar[first_digit]; // to display the first digit.
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LedBuff[4] = LedChar[second_digit]; // to display the second digit.
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LedBuff[3] = LedChar[third_digit]; // to display the third digit.
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LedBuff[2] = LedChar[fourth_digit]; // to display the fourth digit.
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LedBuff[1] = LedChar[fifth_digit]; // to display the fifth digit.
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LedBuff[0] = LedChar[sixth_digit]; // to display the sixth digit.
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}
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}
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void main()
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{
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test4();
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} |