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我有一个应用,它将是非常有利的使用CTMU从地面隔离。例如,可以通过选择第一模拟引脚作为其正输入和第二模拟引脚作为其负输入来区别使用A/D。这意味着A/D测量两个引脚之间的差异,而不是测量相对于地面的单个引脚。这对于CTMU的测量端来说是很好的,但是我无法确定如何使充电侧工作不同。从有几分不足的CTMU文档中,CTMU的恒流源将其电流驱动到A/D的正多路复用器的输出端。这允许您使用任何模拟输入的CTMU,背负在A/D现有的正多路复用器上。CTMU电流源是内部参考地,还是A/D的负多路复用器?如果它是指地面,我看不出有什么不同的方式来使用它。但是如果它以平衡的方式实现,通过连接到A/D的负多路复用器来镜像它的积极一面,那么它突然变得更加强大。我已经张贴了一张请求微芯片的关于CTMU的反馈。那是八个星期前,我还没有一个单一的反应。我希望这里有人分享一些知识。谢谢!
以上来自于百度翻译 以下为原文 I have an application where it would be very advantageous to use the CTMU isolated from ground. For example, it's possible to use the A/D differentially by selecting a first analog pin as its positive input, and a second analog pin as its negative input. This means the A/D is measuring the difference between the two pins, rather than measuring a single pin relative to ground. This is great for the measurement side of the CTMU. But I can't figure out how to get the charging side to work differentially. From the somewhat scanty CTMU documentation, the CTMU's constant current source drives its current into the output side of the A/D's positive multiplexer. This allows you to use the CTMU with any analog input, piggybacking on the A/D's existing positive multiplexer. Does the CTMU current source reference ground internally, or the A/D's negative multiplexer? If it's referenced to ground, I can't see a way to use it differentially. But if it's implemented in a balanced manner, mirroring its positive side by connecting to the A/D's negative multiplexer, then suddenly it's enormously more powerful. I've posted a ticket asking Microchip for feedback on the CTMU. That was EIGHT WEEKS AGO and I haven't had a single response of any kind. I'm hoping someone here has some knowledge to share. Thanks! |
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我一直认为电容式触摸模块CTMU只用于触摸屏,但我看到它实际上是非常通用的,第二个应用笔记意味着它甚至可以用来消除世界饥饿和实现世界和平!http://WW1.Microchip .com /下载/ En/AppNoNe/01250A.PDFHTP://WW1.Microchip .com /下载/En/AppNOTE/CTMU%2002 1375 A.PDFIT显示当前源引用VCC,但为了实现当前流,它还必须有一个电流接收器到VSS。然而,电容或电阻可以通过对ADC的差分输入来监测。ADC多路复用器显然也用于CTMU输出,但是这些将是高阻抗或电流源到地面接收器。一个简单的接地电阻将允许差分输入的第二(低侧)具有与CTMU输出成正比的地上电压,但是真正的差分电流源不引用GND需要单独的隔离电压源。您可能能够设计出第二低电平。-侧电流接收器(可能是电流镜),其与源相同的电流下沉,从而在供电轨的范围内是差动的。
以上来自于百度翻译 以下为原文 I had always assumed the capacitive touch module CTMU was only for touchscreens, but I see that it is actually very versatile, and the second app note implies that it can even be used to eliminate world hunger and achieve world peace! http://ww1.microchip.com/downloads/en/AppNotes/01250a.pdf http://ww1.microchip.com/downloads/en/AppNotes/CTMU%2001375a.pdf It appears that the current source is referenced to Vcc, but in order to achieve current flow, it must also have a current sink to Vss. However, the capacitance or resistance could be monitored by differential input to the ADCs. The ADC multiplexers apparently are also used for the CTMU output(s), but these will be high impedance or current sourcing into a ground-based sink. A simple resistor to ground would allow the second (low side) of the differential input to have a voltage above ground proportional to the CTMU output, but a true differential current source not referenced to GND would need a separate isolated voltage source. You might be able to devise a second low-side current sink (possibly a current mirror) that sinks the same current as the source, and thus would be differential within the range of the supply rails. |
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是的,考虑到一个离散的恒流源的想法,但是CTMU已经集成到设备中,并且Sooooo接近正确的答案。我们会看看他们有什么要说的话。
以上来自于百度翻译 以下为原文 Yep, considering the idea of a discrete constant current source, but the CTMU is already integrated into the device and is soooooo close to the correct answer. I've opened another, separate ticket with Microchip asking this specific question. We'll see what, if anything, they have to say! |
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