本帖最后由 905105948 于 2016-11-19 23:22 编辑
项目需要一个定时器10us一次中断计时间,然后定时器里判断时间,每250us adc采样一次(单通道单次采样),这个方式下,原本采样完8000次,用时应该是2s(250*8000us),结果自己掐表8s多,是否由于定时器中断太多,导致采样耗费时间了,将定时器中断改成50us的话,再测试采样那么多数据,掐表2s多,这个暂时认为比较准确,但是定时器的50us,时间太长,需要10us精度的计时,不知道有没有什么更好的办法控制adc采样,又不耽误计时。10us计时下开adc的中断,由于定时器中断优先级高,次数又太快,adc中断无法进入。照理来说adc最少需要3+13个ADC时钟,不会达到10us这么长时间的呀?求指教。单片机是MSP430FR5949,内部16MHz的DCO作为时钟。
下面是直接在定时器里去采样的,没有用ADC中断的方式。
定时器配置。
- void TimerB0_Init(uint16_t t)
- {
- TB0CCTL0 = CCIE; // TBCCR0 interrupt enabled
- TB0CCR0 = 160; // 10us
- TB0CTL = TBSSEL__SMCLK | MC__UP; // SMCLK, 16M UP mode
- }
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定时器中断
- /*定时器B0中断服务函数*/
- #pragma vector = TIMER0_B0_VECTOR
- __interrupt void Timer0_B0_ISR(void)
- {
- RealTime.u10us++; //10US
-
- if(RealTime.u10us==100000)
- {
- RealTime.u10us=0;
- RealTime.usec++;
- if(RealTime.usec==60)
- {
- RealTime.usec=0;
- RealTime.umin++;
- if(RealTime.umin==60)
- {
- RealTime.umin=0;
- RealTime.uhour++;
- if(RealTime.uhour==24)
- {
- RealTime.uhour=0;
- }
- }
- }
-
- }
- if(RealTime.u10%25==0)//250us采样一次
- {
- A9_sample_start();
- }
- }
复制代码ADC配置
- void ADC_Init(void)
- {
-
- while(REFCTL0 & REFGENBUSY); // If ref generator busy, WAIT
- REFCTL0 |= REFVSEL_2 | REFON; // Select internal ref = 2.5V
- // Internal Reference ON
- // Configure ADC12
- //ADC12CTL0 = ADC12ON | ADC12SHT0_2; // Turn on ADC12, set sampling time
- ADC12CTL0 |= ADC12ON + ADC12SHT0_2+ADC12SHT1_2;
- //ADC12CTL1 = ADC12SHP;
- ADC12CTL1 = ADC12SHP | ADC12SSEL_3 ; // Use sampling clock SMCLK 16M;
- ADC12CTL3 &= 0xFFE0;
- ADC12CTL3 |= ADC12CSTARTADD_9;
- ADC12MCTL9 = ADC12INCH_9 | ADC12VRSEL_1;
-
- ADC12CTL0 |= ADC12ENC;
-
- //ADC12IFGR0 = BIT9;
- }
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ADC采样
- void A9_sample_start(void)
- {
- //while(REFCTL0 & REFGENBUSY); // If ref generator busy, WAIT
- //REFCTL0 |= REFVSEL_2 | REFON; // Select internal ref = 2.5V
- // Internal Reference ON
- // Configure ADC12
- //ADC12CTL0 = ADC12ON | ADC12SHT0_2; // Turn on ADC12, set sampling time
- //ADC12CTL1 = ADC12SHP;
- //ADC12CTL1 = ADC12SHP | ADC12SSEL_3 ; // Use sampling clock SMCLK 8M;
- //ADC12CTL3 &= 0xFFE0;
- //ADC12CTL3 |= ADC12CSTARTADD_9;
- //ADC12MCTL9 &= 0xFFE0;//先清空原来的值
- //ADC12MCTL9 |= ADC12INCH_9 | ADC12VRSEL_1;
- ADC12CTL0 |= ADC12SC;
-
- while (!(ADC12IFGR0 & BIT9));
- __data20_write_short(Cur_Addr+position,ADC12MEM9);
- //ADC12CTL0 &=~ (ADC12ENC + ADC12SC);
- position+=2;
- if(position==0x4000)
- position=0;
- }
复制代码
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小平头技术问答
第二,你的设置啥都没说,型号也不说,G2系列,最少需要4+13 ADCLK,就拿13来算吧,13X0.2us=2.6us,在10内啊,更加说明你的中断写的不合理了,还有这么极限的时间,能保证准确率不,怀疑
AD时间是16+13=29,29X0.2=5.8us,你的系统主时钟是1M的,那中断肯定就不行了,看注释,猜是16M的,那应该没啥问题。。。。。下午回来再看下
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