One way for a microcontroller to retrieve input is known as polling. Polling means repeatedly measuring a sensors value. I will describe how to poll a pushbutton switch and react to its measurement when using a Psoc3 microcontroller.
* Filename: switchpolling.c
* Title: Polling a switch with a Psoc microcontroller
* Description: This source code file is used with a Psoc 3 microcontroller to poll a switch.
* Upon detecting a change in the switches state, An LCD is updated to display the number of
* times the switch has been closed in Hex and decimal format.
* Copyright 2011 BK Turley & Robert Sanson. All rights reserved.
* Redistribution and use in source and binary forms, with or without modification, are
* permitted provided that the following conditions are met:
* 1. Redistributions of source code must retain the above copyright notice, this list of
* conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice, this list
* of conditions and the following disclaimer in the documentation and/or other materials
* provided with the distribution.
* THIS SOFTWARE IS PROVIDED BY BK Turley & Robert Sanson ''AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL BK Turley & Robert Sanson OR
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* or implied, of BK Turley & Robert Sanson.
#include // part specific constants and macros
#include "PSoCAPI.h" // PSoC API definitions for all User Modules
#include // needed to use itoa()
WORD count = 0; // holds the number of switch presses
unsigned char c2; // holds count's value after conversion to a C string.
unsigned char cnt = "Counting "; //a label for LCD
unsigned char lbl = "Hex: Dec:"; //another label for LCD
while (1)//poll, but only increment count once per switch press.
BOOL pressed = SWITCH_Data_ADDR & SWITCH_MASK; //take a measurement of the switch state
pressed = SWITCH_Data_ADDR & SWITCH_MASK;
// Display count to LCD in Hex and Decimal format.
itoa(c2,count,10);// store count's value as a decimal string for display purposes.