Operational Amplifier (OPAMP) output measure sample

Overview

This sample demonstrates how to use the OPAMP driver API.

Building and Running

To build and run this example, users need to configure the following: 1. Configure one channel of the ADC to measure the output of the OPAMP. 2. Use DT to configure the OPAMP. If the OPAMP supports programmable gain, you can set the gain you want to test using property ‘programmable-gain’.

Note: 1. Any gain value should not cause the output of the OPAMP to be less than the theoretical minimum or greater than the theoretical maximum. 2. The output of the OPAMP should not exceed the range of the ADC.

Building and Running for NXP FRDM-MCXA156

Build the application for the FRDM-MCXA156 board.

west build -b frdm_mcxa156 samples/drivers/opamp/output_measure
west flash

Hardware connection (OPAMP0 in differential mode): 1. Positive input channel J2-12 (OPAMP0_INP) connects to a voltage source. 2. Negative input channel R60-3 (OPAMP0_INN) connects to a voltage source. 3. Vout = Vref + (Vinp - Vinn) * Ngain.

Sample output

You will see the inverting and non-inverting gain and the output of the opamp in the terminal. Users can calculate the theoretical output value of the opamp according to the formula and compare it with the ADC measurement value.

The following output is printed:

*** Booting Zephyr OS build v4.2.0-2155-gb21dd897e034 ***
OPAMP output is: 1513(mv)
OPAMP output is: 907(mv)
OPAMP output is: 613(mv)

Note

The values shown above might differ.