Defining the Feedback

There are many different methods to measure a signal and these can vary from using a simple resistor divider network to more complex sensing circuits that use operational amplifiers or opto-isolators. For this reason, and in order to accommodate for the various kinds of feedback networks, the Graphical User Interface (GUI) supports two different methods to define the feedback used. They are:

  • Resistor-Capacitor (RC) Network
  • Fixed Gain limited bandwidth sensor
Feedback-Type-Select-Window.PNG

Resistor-Capacitor Feedback Network

Using the RC Feedback Network allows you to enter specific resistor divider values and the capacitor used for the feedback. This network introduces an attenuation factor and also behaves as a low pass filter limiting signals beyond the frequency of interest. In this window, you must also define the characteristics of the Analog-to-Digital Converter (ADC) using the values defined in the specific dsPIC® DSC datasheet.

  • ADC Resolution: This is determined by the dsPIC DSC hardware and the number of bits of resolution of the ADC module.
  • ADC Latency: This value needs to account for the delay introduced by the Sample&Hold and Conversion delay (for dsPIC33F family this is typically ~600 ns).
  • ADC Operating Voltage: This is the maximum voltage range of the ADC module.

For more information about the ADC Module, see the "Family Datasheets and Reference Manual Documents" page.

RC-Feedback-Network-Window.PNG

Fixed Gain Feedback Network

This feedback option allows you to define a constant gain with a limited bandwidth sensor. This enables the GUI to model the feedback system without having to model complex op-amp based circuitry configurations.
In this window, you must also define the characteristics of the Analog to Digital Converter (ADC) using the values defined in the specific dsPIC DSC datasheet.

  • ADC Resolution: This is determined by the dsPIC DSC hardware and the number of bits of resolution of the ADC module.
  • ADC Latency: This value needs to account for the delay introduced by the Sample&Hold and Conversion delay (for dsPIC33F family this is typically ~600 ns).
  • ADC Operating Voltage: This is the maximum voltage range of the ADC module.

For more information about the ADC Module, see the "Family Datasheets and Reference Manual Documents" page.

Fixed-Gain-Feedback-Window.PNG
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