ADCcN12的最大输出不是4096吗？

嗨，伊北，
通过PGA后，模拟信号将从0～3.96V变化。ADC使用的参考是什么？
VSS是PSOC引脚的接地（0V）。而AGND可以从PSOC设计器提供的各种选项中选择。REF MUX可以用来选择AGND值。
可用的选项是VDD / 2，BandGap，1.6带隙，2带隙，或引脚。
如果AGND是基于VDD的，那么VDD中的改变也会导致AGND的变化。BandGap将保持相当稳定。



     以下为原文
  Hi Nate,
     
    After passing through PGA, the analog signal will vary from 0-3.96V. What is the Reference you are using for the ADC?
     
    Vss is the ground (0V) which is given to the Pin of PSoC. Whereas AGND can be chosen from various options available using PSoC Designer. The Ref Mux can be used to choose the AGND value.
    The options available are Vdd/2, BandGap, 1.6BandGap, 2BandGap, or Pins.
    If AGND is based on Vdd, then changes in Vdd will also cause change in AGND. BandGap will remain fairly stable.

谢谢您！
我把VDD设为5V，REF MUX是[VDD/2 ] +/-[VDD／2 ]，但是当我为ADC设置参数时，只有四种选择：TMR时钟、CNT时钟、输入和时钟相位。我没有看到任何有关参考。
下面是全局资源设置。
PSOC1.BMP
494 K



     以下为原文
  Thank you !
    i set my VDD as 5V,and the ref mux is [vddd/2]+/-[vdd/2], but when i set the parameters for ADC,there are only four options:TMR CLOCK,CNT CLOCK,INPUT and  CLOCKPHASE. i didn't  see anything about reference.
    here are the global resources settings.

•   psoc1.bmp 494.0 K
  
  

一旦REF复用器被设置为[VDDD／2 ] +/-[VDD／2 ]，则在内部选择参考，使得ADC输入现在可以在-VDD / 2到+VDD / 2之间变化。
可以使用全局资源中的“REF MUX”参数来选择对ADC（和其他模拟部分）的引用。以下是在具有全功能模拟块的PSoC中的各种参考设置。
1（Vcc／2）+/-带隙
2（VCC／2）+/-VCC／2
3、Bandgap +/- Bandgap
4（1.6带隙）+/-（1.6带隙）
5（2×Bandgap）+/- Bandgap
6（2×Bandgap）+/-P2〔6〕
7、P2〔4〕＋／Bandgap
8、P2〔4〕+/-P2〔6〕
使用选项7和8，外部电压源可被用作AGND或参考。
使用ReFMUX参数选择的参考对于所有的模拟块是共同的。



     以下为原文
  Once the ref mux is set to [vddd/2]+/-[vdd/2], the reference is selected internally such that now the ADC input can vary between -vdd/2 to +vdd/2.

   

 
    The reference to an ADC (and other analog sections) may be selected using the "Ref Mux" parameter in the Global Resources.

Following are the various reference settings available in a PSoC with full function Analog blocks.
    1.       (Vcc/2)+/- bandgap
    2.       (VCC/2) +/- Vcc/2
    3.       Bandgap +/- Bandgap
    4.       (1.6 Bandgap) +/- (1.6 Bandgap)
    5.       (2*Bandgap) +/- Bandgap
    6.       (2*Bandgap) +/- P2[6]
    7.       P2[4] +/- Bandgap
    8.       P2[4] +/- P2[6]
    Using options 7 and 8, an external voltage source may be used as AGND or Reference.
    The Reference selected using the RefMux parameter is common to all the analog blocks.

谢谢您！
我认为这个范围是0VDD，但是如果我把基准设为Vdd /2-VDD／2，输入一个5V信号，结果会溢出吗？



     以下为原文
  Thank you!
    I thought the range was 0-Vdd.but if i set the Reference as -Vdd/2-Vdd/2 and input a 5V signal ,will the result overflowed?

解决你原来的问题：1。当你说你看到的值大于4096时，应该是因为你可能已经将“DATAFLASH”参数设置为“签名”。在这种数据格式中，ADC在AGND周围给出了正面和负面的结果。例如，如果您将全局资源中的模拟参考参数设置为VDD/2 +/-VDD／2，AGND为2.5V。ADC将为2.5V以上的任何电压和+VE值产生小于+2.5V的+VE值。在2的恭维格式中的AV值将看起来像无符号值更大。超过4096。因此，将DATAFLASH参数设置为未签名。2。对于PGA，应根据输入信号的性质来选择参考。如果你的输入是关于VSS并且仅仅是+VE，那么VSS应该被选择作为参考。如果你的输入是一个双极信号，它可以同时具有+VE和-VE电压，并且相对于AGND，则将参考设置为AGND。为单极信号设置AGND的参考将产生错误的结果。例如，让我们采取一个1.5V的信号馈给PGA增益为2。如果您设置了参考VSS，那么PGA将对VSS的输入放大2倍，得到3.0V。但是如果您设置了AGND的引用，并且如果模拟参考是VDD/ 2 +/-VDD / 2，那么PGA就AGND看到1.5V为-1V，并产生-2V W.R.T的输出。AGND，实际上是0.5V W.R.T VSS。希望这是清楚的。总结，对于输入信号，将PGA引用设置为VSS、ADC、S数据格式到未签名。最好的问候，GSONH PSoC黑客



     以下为原文
  Addressing your original question:

1. When you say you are seeing values greater than 4096, that should be because you may have set the "DataFormat" parameter to "Signed".  In this data format, the ADC gives both posive and negative results around AGND.  For example, if you have set the Analog Reference parameter in the Global resources to Vdd/2 +/- Vdd/2, AGND is 2.5V.  The ADC will produce a +ve value for any voltage above 2.5V and -ve value for a voltage less than 2.5V.  A -ve value in 2's compliment format will look like an unsigned value greater than 4096.  So, set the DataFormat parameter to Unsigned.

2. For the PGA, the reference should be selected depending on the nature of your input signal.  If your input is with respect to VSS and is only +ve, then VSS should be selected as reference.  If your input is a bipolar signal that can have both +ve and -ve voltages and is with respect to AGND, then set the reference to AGND.  Setting the reference to AGND for a unipolar signal will produce wrong results.  For example, let us take a 1.5V signal fed to the PGA with a gain of 2.  If you set the reference to VSS, then the PGA will amplify the input with respect to VSS by a factor of 2 and you get 3.0V.  But if you set the reference to AGND, and if the analog reference is Vdd/2 +/- Vdd/2, then the PGA sees a 1.5V as -1V with respect to AGND and produces an output of -2V w.r.t AGND, which is actually 0.5V w.r.t VSS.  Hope this is clear.

Summarizing, for your input signal, set the PGA reference to VSS, ADC;s data format to unsigned.

Best Regards,
Ganesh
The PSoC Hacker