MCUXpresso SDK Documentation
Open on Repo Open an Issue
Source (.md/.rst) Page PDF (.pdf)

vref_lpadc

vref_lpadc#

Overview#

The vref example shows how to use the vref driver.

In this example, we first get the default trim value of the VREF and measure the VREF output through the LPADC to get the default output voltage. Adjust the trim value by 30 steps to create a 20mv (300.54/3=20mv) voltage difference, The theoretical voltage value should be 20mv greater than or less than the default output voltage, then use the LPADC to measure the VREF output again, the measured voltage value should close to the theoretical voltage.

Supported Boards#

FRDM-IMXRT1186
Hardware requirements

  • Type-C USB cable

  • FRDM-IMXRT1186 board

  • Personal Computer

Board settings

Change Jumper J27 from 1-2 to 2-3

  • Connect ADC CHA1 (J51-8)(GPIO_AD_14) to VREFO(J37-1).

Prepare the Demo

  1. Connect a USB cable between the host PC and the OpenSDA USB port on the target board.

  2. Open a serial terminal with the following settings:

    • 115200 baud rate

    • 8 data bits

    • No parity

    • One stop bit

    • No flow control

  3. Download the program to the target board.

  4. Either press the reset button on your board or launch the debugger in your IDE to begin running the demo.

Running the demo

When the demo runs successfully, the log would be seen on the OpenSDA terminal like:

 vref lpadc example

 vref default trim value is: 7
 vref default output voltage is 1194.595mv

 current setting trim value is 37
 current theoretical voltage is 1214.595mv
 current actual voltage is 1214.817mv

Due to the errata051385, the ADC reference voltage is connect to the VDDA_ADC_1P8.

MIMXRT1180-EVK
Hardware requirements

  • Mini/micro USB cable

  • MIMXRT1180-EVK board

  • Personal Computer

Board settings

  • Connect ADC CH7A (J41-2) to VREFO(J10-1).

Prepare the Demo

  1. Connect a USB cable between the host PC and the OpenSDA USB port on the target board.

  2. Open a serial terminal with the following settings:

    • 115200 baud rate

    • 8 data bits

    • No parity

    • One stop bit

    • No flow control

  3. Download the program to the target board.

  4. Either press the reset button on your board or launch the debugger in your IDE to begin running the demo.

Running the demo

When the demo runs successfully, the log would be seen on the OpenSDA terminal like:

 vref lpadc example

 vref default trim value is: 7
 vref default output voltage is 1194.595mv

 current setting trim value is 37
 current theoretical voltage is 1214.595mv
 current actual voltage is 1214.817mv

Due to the errata051385, the ADC reference voltage is connect to the VDDA_ADC_1P8.

Contents