Routing Internal Reference to an External Pin in PSoC® Analog Coprocessor - KBA211662

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Question:

How do I route the internal reference to an external Pin in PSoC Analog Coprocessor?

 

Answer:

The Programmable Voltage Reference Component (PVref) provides a reference voltage for use with the internal analog blocks. The reference voltage can also be routed to an external pin. Follow the steps given below:

 

  1. Select and place a PVref Component, available under the Analog group in the Component Catalog.
  2. Configure the PVref Component to the required reference voltage. There are two reference sources – 1.2 V bandgap and VDDA (supply voltage). Select the Reference source using the radio button and the Voltage reference from the drop-down box. See Figure 1. 

    Figure 1. PVref Component Configuration

    1.png
  3. Place an Opamp Component, available under Analog > Amplifiers group in the Component Catalog.
  4. Configure the Opamp Component with the following parameters:    
      1. Mode: Follower
      2. Output: Output to Pin

Opamp is configured in the follower mode to buffer the reference voltage from PVref Component, which has high output impedance. Output to Pin configuration is required to route the Opamp output to a pin. See Figure 2.  

Figure 2. Opamp Component Configuration

2.png

    5. Place an Analog Pin Component available under Port and Pins group in the Component Catalog. Leave the settings at their default values.

    6. Route the PVref output to the Opamp input and the Opamp output to the Analog Pin Component. See Figure 3.  

Figure 3. Routing PVref Output to Pin

3.png

   7.  Finally, select a physical pin for the Opamp output (in this case, Pin_1) in the Pins tab of the <Project_Name> .cydwr file