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嗨，伙计们。我开始编程PIC微控制器，我正在使用的项目使用一个DSPIC33 FJ128MC804。现在我正在配置ADC来读取来自传感器的电压，并且我使用AVDD和AVSS作为参考。我注意到当电池电量下降时，我从传感器得到的值更小。DSPIC33是否具有不依赖于电源的内部电压基准，或者需要使用齐纳二极管或像TL431这样的调节器来创建一个电压基准？我想用这个参考来监视我的电池充电。我在这个论坛上看到一些较小的芯片（如PIC18）有一个内部固定电压基准（FVR）。谢谢您的时间。
以上来自于百度翻译 以下为原文 Hi guys. I started programming Pic microcontrollers and the project that I'm working on uses a dsPic33FJ128MC804. Now I'm configuring the ADC to read the Voltage from a sensor and I'm using Avdd and Avss as reference. I noticed that when the battery charge goes down, the values I get from my sensor are smaller. Does the dsPic33 have an internal voltage reference that does not depend on the power source or I need to create one by using a Zener diode or a regulator like TL431? I want to use this reference to monitor the charge of my battery. I read on this forum that some of the smaller chips(like pic18) have an internal fixed voltage reference (FVR). Thank you for your time. 
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8个回答
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另外，一些PIC24和DSPIC33器件都有内部电压基准，但VMCR4…MC804没有，或者它根本不在硅芯片中，或者它的功能很差，它在设备被引入之前被从文档中移除。Y将VCAP引脚上的电压馈送到ADC输入，它可能没有带隙基准的方式补偿，因此可能随环境温度和其他因素而变化。根据数据表，VCAP引脚的电压应该在2.5 V左右，只要电源电压为3 V或更高。迈西尔
以上来自于百度翻译 以下为原文 Hi, Also some PIC24 and dsPIC33 devices have Internal Voltage Reference, FVR but ...MC804 have Not. Either it isn't in the silicon chip at all, or it function so poorly, that it was removed from documentation before the device was introduced. In order to get an impression of Battery status, you could try to feed the voltage on VCAP pin to a ADC input. It is probably Not compensated the way a bandgap reference is, so probably may vary with ambient temperature and other factors. According to datasheet, voltage at VCAP pin should be around 2.5 V, as long as supply voltage is 3.0 V or higher. Mysil |
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除了一个外引线检测所使用的带隙基准之外，这一点没有参考电压。另一方面，考虑到内部参考的公差，您最好用外部参考。（在某种程度上取决于您的精度要求，但在某些项目中）。我目前正在设计0.5%个NOM。参考（加上0.5%在整个温度范围内）。这样的精度在廉价的（甚至昂贵的）微控制器中是不可用的。
以上来自于百度翻译 以下为原文 This one goes without a reference voltage other than the band gap reference used by the brown-out detection. On the other hand - given the tolerances of the internal references - you might be better off with an external reference. (Depends somewhat on your precision requirements, but in some project I'm currently designing-in a 0.5 % nom. reference (plus another 0.5 % over the whole temperature range). Such precision is simply not available in cheap (and even expensive) microcontrollers. |
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我原以为读数会随着你的引用而变大。
以上来自于百度翻译 以下为原文 I would have expected the readings to get BIGGER as your reference fell. |
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传感器是由VDD或AVDD提供的吗？否则，我预计ADC输出代码会上升。
以上来自于百度翻译 以下为原文 Is the sensor supplied from VDD or AVDD? Otherwise I'd expect the ADC output codes to rise. |
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是的，传感器是由VDD提供的，而且我注意到只有当电池供应低于APROX 63V时，基准才开始降低它的值。高于这个值，它是可用的。所以我只需安装一个蜂鸣器，告诉我什么时候给电池充电。非常感谢你！
以上来自于百度翻译 以下为原文 Yep, the sensor is supplied from Vdd. Also I noticed that only when the battery Supply falls below aprox 6.3V, the reference starts to lower it's value. Above that value, It's usable. So I will just attach a buzzer that will tell me when to charge the battery. Thank you very much! |
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嗨，DinoIf电池电压是6.3伏或更高，那么DSSPIC33不能直接从电池供电，必须有一个调节器在电源到AVDD和VDD。你没有在原始消息中解释这一点。在这种情况下，你不需要一个FVR参考来监测电池电压。AVDD作为参考电压将足以监测电池电压。将需要一个分压器，1/2或1/3，将电池电压降低到更少。比AVdd，输入到ADC引脚。迈西尔
以上来自于百度翻译 以下为原文 Hi, Dino If battery voltage is 6.3 Volt or Higher, then dsPIC33 cannot be powered directly from battery, there have to be a regulator in the power supply to AVdd and Vdd. You didn't explain this in the original message. In this case, you do not need a FVR reference to monitor Battery voltage. AVdd as reference voltage will be adequate for monitoring the battery voltage. There will be a voltage divider needed, 1/2 or 1/3, to divide battery voltage down to something less than AVdd, for input to a ADC pin. Mysil |
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2018-8-29 16:04:33
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