数字麦克风:I2S数据输出 [英] Digital microphone : I2S data output

问题描述

我一直在玩一些带有I2S接口的数字麦克风.我设法使其正常工作(带有小型I2S内存板的Arduino板).至少，我认为是的.

I have been playing around with some digital microphones, which have an I2S interface. I managed to get it working (Arduino board with small I2S mems board). At least, I think I did.

在阅读I2S规范或麦克风数据表时，我似乎找不到以下简单问题的答案； 1.数字值代表什么? 2.如何将数字值转换为dbFS(然后转换为dbSPL)?

When reading the I2S specification, or the microphone datasheet, I can not seem to find the answer to the following simple questions; 1. What do the digital values represent? 2. How do you convert the digital values to dbFS (and then later an dbSPL)?

SPH0645LM4H-B(Knowles)麦克风似乎输出所有负值(?).我读过某个地方，您必须减去中点"以消除较大的DC偏移?！ 另一方面，Invensense的一名支持工程师向我解释说，ICS-43434输出的正值和负值代表信号相对于+/-满量程的幅度".

The SPH0645LM4H-B (Knowles) microphone seems to output all negative values (?). I read somewhere you have to "subtract the midpoint" to eliminate the large DC offset?! On the other hand, a support engineer at Invensense explained to me that the ICS-43434 outputs positive and negative values which "represent the amplitude of the signal relative to +/-full scale".

我希望I2S成为标准.不是这样吗??

I expected I2S to be a standard; isn't that the case ... ?

推荐答案

您必须保存数字化数据的每个样本，当转换为十进制时，这个24位的字将为您提供电压.此电压是计算RMS值所需的电压，随后需要计算db SPL.

You have to save each sample of the digitized data, this word of 24 bits when converted to decimal, will give you a voltage. This voltage is what you need to calculate RMS value, and later on calculate your db SPL.

您要使用哪个arduino板才能使其正常工作?大多数arduino没有I2S通信，我认为Arduiino Zero和MKR是可用于Taks的工具.如果您使用具有浮点，32位处理器，DMA等的STM32微控制器，将会获得更好的性能.

Which arduino board are you using to make it work? most arduino doesn't have I2S communication, I think Arduiino Zero and MKR are the ones available for the taks. You would achieve a better perfomance if you use STM32 microcontrollers, which have floating point, 32 bits processor, DMA.. etc.

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