数据手册上说应该先写低字节,再写高字节
因为在写低字节的同时,监时寄存器的内容会写入高字节.但是我看AVR-GCC编译后的汇编语言是这样的:
void timer1_init(void)
{
1c2: cf 93 push r28
1c4: df 93 push r29
1c6: cd b7 in r28, 0x3d ; 61
1c8: de b7 in r29, 0x3e ; 62
DDRD |= _BV(PD5);
1ca: 80 91 31 00 lds r24, 0x0031
1ce: 80 62 ori r24, 0x20 ; 32
1d0: 80 93 31 00 sts 0x0031, r24
TCCR1A = 0x00;
1d4: 10 92 4f 00 sts 0x004F, r1
TCCR1B = 0x00; //start
1d8: 10 92 4e 00 sts 0x004E, r1
TCNT1L = 0x00;
1dc: 10 92 4c 00 sts 0x004C, r1
TCNT1H = 0x00; //REG = 65536 - （Fosc/分频）/Fobj)
1e0: 10 92 4d 00 sts 0x004D, r1
//OCR1AL = 0X00;
//OCR1AH = 0X00;
//OCR1AL = 0XFF;
//OCR1AH = 0XEF;
OCR1A = 0XEFff;
1e4: 8f ef ldi r24, 0xFF ; 255
1e6: 9f ee ldi r25, 0xEF ; 239
1e8: 90 93 4b 00 sts 0x004B, r25
1ec: 80 93 4a 00 sts 0x004A, r24
ICR1L = 0XFF;
1f0: 8f ef ldi r24, 0xFF ; 255
1f2: 80 93 46 00 sts 0x0046, r24
ICR1H = 0XFF;
1f6: 8f ef ldi r24, 0xFF ; 255
1f8: 80 93 47 00 sts 0x0047, r24
TCCR1A = 0x82;
1fc: 82 e8 ldi r24, 0x82 ; 130
1fe: 80 93 4f 00 sts 0x004F, r24
TCCR1B = 0x19; //start
202: 89 e1 ldi r24, 0x19 ; 25
204: 80 93 4e 00 sts 0x004E, r24
TIMSK = TIMSK | 0X10;
208: 80 91 59 00 lds r24, 0x0059
20c: 80 61 ori r24, 0x10 ; 16
20e: 80 93 59 00 sts 0x0059, r24
212: df 91 pop r29
214: cf 91 pop r28
216: 08 95 ret
00000218 <disable_timer1>:
}
很明显编译后汇编是先写高字节再写低字节.
以上这一段代码是快速PWM模式14,比较匹配时OC1A清零,在TOP时置位.
程序将OCR1A赋值:0XEFFF,但是软件仿真是,执行OCR1A = 0XEFFF后,
OCR1A寄存器的值为0x01ff,真不明白错在哪里?
OC1A引脚也没有输入想象中的波形,匹配中断可以正常产生,不知哪里出错,请大家帮忙!
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