AN3137 datasheet(38/42 Pages) STMICROELECTRONICS

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Source code examples

AN3137

38/42

Doc ID 16983 Rev 3

A.2.1

Program flow

The main.c file contains the main program loop - in function main(). At the beginning, the

basic MCU initialization is performed: clock, interrupts, display... Then the main testing loop

begins - it consists of series of steps.

Each test step contains a write to the LCD display to display information about the running

test and then contains the call to test routine itself. The test routines are provided in the

corresponding file. To continue from one test to the next, the user must press a “Key” button

on evaluation board. After all tests are done, then the test loop runs again.

Tests are:

●

TestADCAveraging();

–

ADC in single mode - channel 24

–

averaging method applied

●

TestADCWhiteNoise();

–

ADC in single mode - channel 24

–

averaging method applied

●

TestADCDigitalFilter50Hz();

–

ADC in single mode - channel 24

–

external timer trigger

–

simple digital comb 50 Hz filter applied

●

TestADCCalibration();

–

ADC in single mode

–

simple linear model applied (offset and gain calibrated)

●

TestADCFFT();

–

ADC in single mode

–

external timer trigger

–

16-point FFT applied

A.2.2

User interface description

A user interface is available to test the described example. It consists of an LCD display and

buttons on the evaluation board. These are the steps to follow:

Load the example firmware onto the evaluation board

Run the program (resetting the evaluation board); the invitation screen appears.

Connect the signal to the BNC connector

Press the joystick

The main program loop begins, with the following methods shown:

Averaging method:

●

the first line on LCD shows the difference (maximum-minimum) from raw samples

(buffer is 200 samples)

●

the second line on LCD shows the difference (maximum-minimum) from averaged

samples (floating average of 10 samples)

●

to stop the method press the “Key” button

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