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# 1.6 CMP Configurable Reference

This example application shows how to use the CMP Peripheral library to compare voltage level on the negative input with the internal configurable reference voltage.

## Description

The peripheral named comparator voltage reference (CVR) can be used by the CMP peripheral. It generates a voltage that can be connected internally to the +ve input of the any of the comparators in the device. This allows to set flexible compare voltages.

## Downloading and Building the Application

To clone or download this application from Github, go to the main page of this repository and then click Clone button to clone this repository or download as zip file. This content can also be downloaded using content manager by following these instructions.

Path of the application within the repository is apps/cmp/cmp_configurable_reference/firmware.

To build the application, refer to the following table and open the project using its IDE.

Project Name | Description
--- | ---
pic32mx470_curiosity.X | MPLABX project for Curiosity PIC32MX470 Development Board
pic32mx_xlp_sk.X | MPLABX project for PIC32MX274 XLP Starter Kit

## Setting Up the Hardware

The following table shows the target hardware for the application projects.

Project Name | Description
--- | ---
pic32mx470_curiosity.X | Curiosity PIC32MX470 Development Board
pic32mx_xlp_sk.X | PIC32MX274 XLP Starter Kit

### Setting Up Curiosity PIC32MX470 Development Board

- To run the demo, the following additional hardware are required:
  - USB UART click board
- Connect mini USB cable to the ‘Debug USB’ connector(J3) on the board to the computer
- Install an USB UART click board on to the mikroBUS socket J5
- Connect mini USB cable to the USB UART click board and PC
- Pin 11 (C1INC) on J14 is the negative input, connect it to a voltage below the reference voltage (~2V from CVR peripheral) to trigger interrupt
  Note: Ensure that the series resistors on the mikroBUS headers are of value 0 Ohms.

### Setting Up PIC32MX274 XLP Starter Kit

- To run the demo, the following additional hardware are required:
  - USB UART click board
- Connect micro USB cable to the ‘Debug USB’ connector(J9) on the board to the computer.
- Install an USB UART click board on to the mikroBUS socket J5
- Connect mini USB cable to theUSB UART click board and PC
- Pin 12 (C3INB) on J2 is the negative input. Connect it to a voltage below the reference voltage (~2V from CVR peripheral) to trigger interrupt

## Running the Application

1. Open the Terminal application (Ex.: Tera term) on the computer
2. Connect to the “USB to UART” COM port and configure the serial settings as follows:
   - Baud : 115200
   - Data : 8 Bits
   - Parity : None
   - Stop : 1 Bit
   - Flow Control : None
3. Build and Program the application project using its IDE
4. Following message is output on console:

   Board | Console Output
   --- | ---
   Curiosity PIC32MX470 Development Board |
   PIC32MX274 XLP Starter Kit |