vref_example#
Overview#
The vref example shows how to use the vref driver.
In this example, the adc16 module is initialized and used to measure the VREF output voltage. So, it cannot use internal VREF as the reference voltage.
Then, user should configure the VREF output pin as the ADC16’s sample input. When running the project, it will firstly measure the VREF output voltage within the default (factory) trim value. Then, it will measure the VREF output voltage under different trim values.
Supported Boards#
FRDM-K22F
Hardware requirements
Mini/Micro USB cable
FRDM-K22F board
Personal Computer
Board settings
No special setting is needed.
Prepare the Demo
Connect a USB cable between the PC host and the OpenSDA USB port on the board.
Open a serial terminal on PC for OpenSDA serial device with these settings:
115200 baud rate
8 data bits
No parity
One stop bit
No flow control
Download the program to the target board.
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 example
ADC16_DoAutoCalibration() Done.
ADC Full Range: 4096
Defalut (Factory) trim value is :34
ADC value: 1336
Use trim value: 0
ADC value: 1340
Use trim value: 4
ADC value: 1338
……
Use trim value: 60
ADC value: 1337
TWR-KM34Z50MV3
Hardware requirements
Micro USB cable
TWR-KM35Z50MV3 board
Personal Computer
Board settings
Connect VREF_OUT (J2-2) to J25-24(ADC_SE15).
Prepare the Demo
Connect a USB cable between the PC host and the OpenSDA USB port on the board.
Open a serial terminal on PC for OpenSDA serial device with these settings:
115200 baud rate
8 data bits
No parity
One stop bit
No flow control
Download the program to the target board.
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 example ADC16_DoAutoCalibration() Done. ADC Full Range: 4096 Defalut (Factory) trim value is :38 ADC value: 1506 Use trim value: 0 ADC value: 1464 Use trim value: 4 ADC value: 1489 Use trim value: 8 ADC value: 1468 Use trim value: 12 ADC value: 1473 Use trim value: 16 ADC value: 1478 …… ADC value: 1496 Use trim value: 56 ADC value: 1481 Use trim value: 60 ADC value: 1492
TWR-KM35Z75M
Hardware requirements
Micro USB cable
TWR-KM35Z75M board
Personal Computer
Board settings
Connect VREF_OUT (J2-2) to J25-24(ADC_SE15).
Prepare the Demo
Connect a USB cable between the PC host and the OpenSDA USB port on the board.
Open a serial terminal on PC for OpenSDA serial device with these settings:
115200 baud rate
8 data bits
No parity
One stop bit
No flow control
Download the program to the target board.
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 example ADC16_DoAutoCalibration() Done. ADC Full Range: 4096 Defalut (Factory) trim value is :38 ADC value: 1506 Use trim value: 0 ADC value: 1464 Use trim value: 4 ADC value: 1489 Use trim value: 8 ADC value: 1468 Use trim value: 12 ADC value: 1473 Use trim value: 16 ADC value: 1478 …… ADC value: 1496 Use trim value: 56 ADC value: 1481 Use trim value: 60 ADC value: 1492