Develop a Non-inverting Amplifier Using PIC18F56Q71

 To begin, first open MPLAB X IDE and connect the Curiosity Nano Development board.

Click the New Project button in the top left corner of the menu.

Select Application Project and click Next.

Select your device. This demonstration uses a PIC18F56Q71 device and Curiosity Nano tool.

Select a compiler.

Name your project, assign its location, and click Finish.

After the project is created, click the blue MCC shield at the top.

From the MCC interface, navigate to Project Resources under the Resource Management tab.

Since the PIC18F56Q71 Curiosity Nano and an internal oscillator are being used, Configuration Bits under Project Resources should be opened.  Make the the following sections:

• External Oscillator Selection: Oscillator not enabled 
• Reset Oscillator Selection: The appropriate oscillator for your project. (This demonstration uses the 64MHz HFINTOSC.)

Now we need to set up the test bench to display the output. Start by adding UART under Device Resources.

Then set the PLIB to UART2 on the window that pops up.

Once UART2 appears, change the Requested Baudrate to 115200. 

Next add the ADC from Device Resources.

Select the ADC tab and from its Easy View tab, change Result Alignment to left justified. 

Under Context 1, change the Positive Channel Selection to OPA1IN0+.

Now let’s add the op amp. Navigate back to Device Resources, find the OPAMP module and add OPA1.

Under the OPA1 Easy View change the Op Amp Configuration from Direct Connection to Pins to Non-Inverting Programmable Gain Amplifier, then select Enable Internal Output.

Scroll down to Programmable Gain and Feedback Selection and use Internal Resistor Ladder Selection to select the appropriate gain. This example will use a R2/R1 of 1.

Check for the desired gain. The gain of a non-inverting configuration will be (1+R2/R1), meaning this example will have a gain of 2.

Next, navigate down to the Pin Grid View to assign the RX and TX pins for the UART2 peripheral. Assign the UART2 TX2 pin to RB4.

Click Generate under Project Resources.

Once generated, switch from the Resource Manager tab on the left to Projects and navigate to your project’s source files. Open main.c and add the following code to the while loop:

There are many ways to take an ADC reading and send it to UART including using the DMA peripheral to eliminate the CPU from the process, however, ADC_ChannelSelectAndConvert() is the easiest for the purposes of this demonstration.

Click Make and Program Device Main Project.

Connect the waveform generator, potentiometer, or analog sensor to pin RA2.

Open Data Visualizer   and under the device Curiosity Nano, menu click the gear for the serial COM port and change the baud rate to 115200.

Add the COM port to the time plot () and click play.

The accompanying image shows the results in Data Visualizer.

Here is the displayed ADC reading of the signal from the waveform generator passing through the op amp in a programmable gain amplifier configuration. The incoming signal from the waveform generator is the same, but the new reading is double the previous signal and maxes out at a reading of approximately 240 on the y-axis.