模拟电压变化中断该怎么办？

电压范围是多少？你想知道多少变化？你必须多久才能认识到这种变化？当然，我们需要更多的细节。



      以下为原文

    What voltage range? How much of a change do you wish to recognize? How quickly must you recognize the change? Certainly more detail would be needed for this...

它可以用内部或外部比较器来完成。一些PIC已经建立了外围设备来完成这项工作。



      以下为原文

    It can be done with either an internal or external comparitor.
Some PICs have built in peripherals to do this.
 

电压范围0～5V。变化50MV。我使用16F1508，因为我需要NCO模块



      以下为原文

    Voltage range 0-5v . Change of 50mv . I use 16f1508 because i need NCO module

哪些图片有这个？



      以下为原文

    Which pics have this ?

我相信你是指内部比较器，16F1508有2。然而，我看到在使用一个比较器看到一个未知的直流电压（从0到5伏）的50毫伏变化是困难的。您可以使用A/D来连续地检查电压并测试结果的变化（16f1508具有10位A/d-在5伏时接近5mV的分辨率）。这不会很快，所以对于快速响应时间的需求是不起作用的。电压变化缓慢还是迅速？非常快速的变化可以AC耦合到比较器并作为尖峰检测，但你需要仔细选择滤波器组件并使用两个比较器（正电压变化和负电压变化），或者你需要一个具有足够分辨率的D/A（16f1508中的内部D/A（DAC）只有5bi）。T分辨率或约155毫伏分辨率在5伏特）。然后使用D/A输出作为比较器的输入：用A/D读取电压，保存到D/A，变化将导致比较器输出（仍然需要使用两个比较器来获得pos/neg变化）。



      以下为原文

   
I believe you are referring to the internal comparator, which the 16f1508 has 2. However I see difficulty in trying to use a comparator to see a 50 mV change in an unknown DC voltage (from 0 to 5 volts). You could use the A/D to continuously check the voltage and test the results for a change (the 16f1508 has a 10 bit A/d - close to 5mV resolution at 5 volts). This will not be very fast so it won't work for quick response time needs. Does the voltage change slowly or rapidly? Very rapid changes could be AC coupled into a comparator and detected as a spike but you will need to select the filter components carefully and use two comparators (positve and negative voltage change).
Or you will need a D/A with enough resolution (the internal D/A (DAC) in the 16f1508 is only 5 bit resolution or approx. 155 mV resolution in 5 volts). Then use the D/A output as an input to the comparator: read the voltage with the A/D, save to the D/A, changes will result in a comparator output (still need to use both comparator to get pos/neg changes).

一些更新的图片在A/D读数上有中断。但我不确定是哪一个，或者它叫什么。



      以下为原文

    Some of the Newer PICs have interrupt on A/D reading.  But I am not sure which ones, or what it is called.

你是说这些图片有一个中断，是由模拟输入的改变触发的吗？这将是有用的，但我不知道这个外设，它是如何运作的？大多数（也许全部）A/D外围设备在转换完成时将触发一个中断，但我不知道模拟转换的中断。



      以下为原文

   
Are you stating that these pics have an interrupt triggered by a change at an analog input? That would be useful however I am not aware of this peripheral, how does it operate? Most (maybe all) of the A/D peripherals will trigger an interrupt on completion of conversion but I am unaware of an interrupt on analog change.

如果你切换到PIC16F1713，你会得到一个8位的DAC，你可以用它作为比较器的参考而不会失去NCO。如果我后面的餐巾数学是正确的，你应该能够得到接近50mV与8位DAC和5V偏移比较器。你可以设置比较器来中断正向或负向输出边缘。您可能希望启用零延迟过滤器，以尽量减少聊天。



      以下为原文

    If you switch to a PIC16F1713 you will get a 8bit DAC that you can use as a comparator reference without loosing the NCO.  If my back of napkin math is correct you should be able to get close to 50mV with 8 bits on the DAC and 5mV offset on the comparator.  You can set up the comparator to interrupt on positive or negative going output edge.  You probably want to enable zero latency filter to minimize chatter.

有人把过去的链接，我没有时间看。我记得它涉及的A/D和比较。



      以下为原文

    Someone put a link in the Past, I do not have time to look.
As I recall it involved the A/D  and a compare with that.

使用A/D和比较器是一个简单的概念，但在这张图片的D/A不会给你50mV的分辨率您正在寻求。您可以使用PWM模块之一来产生具有更高分辨率的DC参考电压，这将需要非常仔细的滤波以消除/减少pwm噪声到可接受的水平（将需要远远小于50mV的噪声）。此外，您不能快速改变pwm/参考电平，因为重过滤将防止快速变化，所以这种方法的有效性将再次取决于所需的响应时间。



      以下为原文

    Using the A/D and a comparator is a simple concept however the D/A in this pic will not give you the 50 mV resolution you are seeking. You could use one of the PWM modules to produce a DC reference voltage with more resolution, it will require very careful filtering to eliminate/reduce the pwm noise to an acceptable level (will need to be much less than 50 mV of noise). Also you could not change the pwm/reference level quickly as the heavy filtering will prevent rapid changes so again the usefulness of this approach will depend on the response time needed.

PIC对于所述任务的一个很好的选择，只要从20个引脚到28个引脚的改变不是一个因素。



      以下为原文

   
A good choice for a pic for the stated task as long as the change from 20 pins to 28 pins is not a factor.

改变PIC不是问题，但是有更简单的方法来做。一些内置了这个功能的集成电路？这是变频器的开关，我能用电容器吗？输入比较器+引脚，引脚通过电容输入？什么电容值需要使用，也需要电阻器？



      以下为原文

    Change pic is not problem but is there easier way to do that . some ic that had this function built-in ? This is pot change from frequency inverter .Can i use capacitor . Input to comparator + pin , - pin to input through capacitor ? What capacitor value need to use and also is resistor needs ?