Istvan Cserny / Mbed 2 deprecated 05_comparator_demo

Simple program to demonstrate the basic functions of the analog comparator of the FRDM-KL25Z board.

Dependencies:   ComparatorIn mbed

Fork of ComparatorIn_demo by Frank Vannieuwkerke

ComparatorIn demo

Simple program to demonstrate the basic functions of the analog comparator of the FRDM-KL25Z board.

The blue LED flashes after 2 sec delay. The green LED is driven by the interrupts of the Analog Comparator (LED ON at rising edge, LED OFF at falling edge).

The output of the Analog Comparatir is also tested by polling, the result is printed out at the standard output (UART0). The default speed and format (9600 bps, 8,N,1) are used.

Credits

This program is based on the ComparatorIn library and the ComparatorIn_demo program written by Frank Vannieuwkerke

Used library:

Hardware requirements:

  • FRDM-KL25 board
  • CdS photoresistor pulled up by 10 k

/media/uploads/icserny/05_comparator_demo.png

main.cpp

Committer:
icserny
Date:
2015-11-18
Revision:
8:a5b18dfe684f
Parent:
7:a4f884972a0e

File content as of revision 8:a5b18dfe684f:

/** 05_comparator_demo
 *  Simple program to demonstrate the basic functions
 *  of the analog comparator of the FRDM-KL25Z board.
 *
 *  Used library:
 *   - ComparatorIn //https://developer.mbed.org/users/frankvnk/code/ComparatorIn/
 *     written by Frank Vannieuwkerke
 *
 *  Hardware requirements:
 *   - FRDM-KL25 board
 *   - CdS photoresistor pulled up by 10 k
 *   - Connecect the midpoint of the divider to PTE29
 *
 *            10k          CdS photoresistor
 *   +3.3V --/\/\/\---+---/\/\/\---- GND
 *                    |
 *                  PTE29
 *
 */

#include "mbed.h"
#include "ComparatorIn.h"
 
DigitalOut blinker (LED_BLUE);      // blinking LED
DigitalOut cmpled (LED_GREEN);      // signing comparator status
AnalogIn cmp_lvl (PTE29);           // ADC input to check comparator input
ComparatorIn compi(PTE29, PTE30);   // in+ = PTE29, in- = 12-bit DAC 
 
// Comparator interrupt callback functions
void cmp_rise_ISR(void)
{
    cmpled = 0;                     // LED ON at rising edge
}
 
void cmp_fall_ISR(void)
{
    cmpled = 1;                     // LED OFF at falling edge
}
 
 
 
int main()
{
    cmpled = 1;                     // LED OFF at the beginning
 
    compi.rising(&cmp_rise_ISR);    // Set pointer to rising interrupt function
    compi.falling(&cmp_fall_ISR);   // Set pointer to falling interrupt function
    compi.treshold(0.3);            // Set comparator threshold to 1V = 0.3 * 3.3V
 
    while(1)
    {
        printf("Light sensor : %7.5f Volt\n",cmp_lvl*3.3);
        blinker = 1;                // binking LED OFF
        wait(2);                    // wait for 2 sec
        blinker = 0;                // blinking LED ON
        wait(0.2);
        if (compi.status() == 0x01) // poll comparator status
        {
            printf("*** Treshold reached : %7.5f\n",cmp_lvl*3.3);
        }
    }
}