Contains code for debouncing noisy ditital inputs, like buttons. More...

Detailed Description

Contains code for debouncing noisy ditital inputs, like buttons.

Author: Modtronix Engineering

Compiler:: MPLAB XC16 Compiler

Description

Functions for debouncing noisy digital inputs, like buttons for example. See Usage for details how to use it. This module is automatically enabled in the system as soon as any DEBOUNCE_GET_PORTn defines are added to the projdefs.h file (as described in "Usage" section).

Configuration

The following defines are used to configure this module, and should be placed in projdefs.h. Note that all items marked [-DEFAULT-] are defaults, and do not have to be placed in projdefs.h if they contain desired configuration! For details, see Project Configuration.

// *********************************************************************
// ------------ Debounce Configuration (from nz_debounce.h) -------------
// *********************************************************************
//Define functions for reading each port's value. ALWAYS define from 1 and up, with NO gaps!
//For example, if using 3 ports, use first 3 (1,2 and 3), AND NOT 1,2 and 4!
#define DEBOUNCE_GET_PORT1()
#define DEBOUNCE_GET_PORT2()
#define DEBOUNCE_GET_PORT3()
#define DEBOUNCE_GET_PORT4()
#define DEBOUNCE_GET_PORT5()
#define DEBOUNCE_GET_PORT6()
#define DEBOUNCE_GET_PORT7()
#define DEBOUNCE_GET_PORT8()
//Define debounce times. Must be multiples of 20ms
#define DEBOUNCE_RST            ( 40 )      //40ms debounce [-DEFAULT-]
#define DEBOUNCE_REPEAT         ( 280 )     //280ms first repeat [-DEFAULT-]
#define DEBOUNCE_REPEAT_TIMES   ( 2 )       //2 times = 2 x 280ms = 560ms [-DEFAULT-]
#define DEBOUNCE_REPEAT2        ( 160 )     //100ms following repeats [-DEFAULT-]
#define DEBOUNCE_REPEAT2_TIMES  ( 10 )      //10 times = 10 x 160ms = 1.6 Second [-DEFAULT-]
#define DEBOUNCE_REPEAT3        ( 80 )      //80ms [-DEFAULT-]
#define DEBOUNCE_REPEAT3_TIMES  ( 20 )      //20 times = 20 x 80ms = 1.6 Seconds [-DEFAULT-]
#define DEBOUNCE_REPEAT4        ( 40 )      //60ms [-DEFAULT-]

Usage

To use this module, the following must be done:

Copy the Configuration section above (from nz_debounce.h) to the projdefs.h file.
In this "Configuration" section, change any default values if required (if default values should be used, define is not required in projdefs.h).
Complete the DEBOUNCE_GET_PORTn defines for all ports that should be debounced.
Add nz_debounce.c to the MPLAB project.
Include nz_debounce.h in the c file it is used in.
All DONE! The functions defined in this file can now be used in the project.

Examples

An example how to use this module to debounce buttons connected to ports 4 and 7 (old port names X4 and X7). First, the following must be added to the projdefs.h file:

#define DEBOUNCE_GET_PORT1() PIN_04

#define DEBOUNCE_GET_PORT2() PIN_07

After doing this, this module will automatically be enabled in the system (debounceService() is called every 20ms). We can now use the debounceGetLatchedPort() function to get the debounced port values. For example:

DIR_04 = INPUT_PIN; //Configure port 4 (old port name X4) as an input
PULLDOWN_04 = TRUE;  //Enable pull-down resistor on port 4 (old port name X4)
//Get debounced port 1
if(debounceGetLatchedPort(1)) {
    //... Do something
}

If a button is attached to pin 4 (old port name X4), it should be tied to 3.3V via a resistor(10k for example). And, the internal pull-down resistor of port 4 (X4) should be enabled.

Software License Agreement

The software supplied herewith is owned by Modtronix Engineering, and is protected under applicable copyright laws. The software supplied herewith is intended and supplied to you, the Company customer, for use solely and exclusively on products manufactured by Modtronix Engineering. The code may be modified and can be used free of charge for commercial and non commercial applications. All rights are reserved. Any use in violation of the foregoing restrictions may subject the user to criminal sanctions under applicable laws, as well as to civil liability for the breach of the terms and conditions of this license.

THIS SOFTWARE IS PROVIDED IN AN 'AS IS' CONDITION. NO WARRANTIES, WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE. THE COMPANY SHALL NOT, IN ANY CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES, FOR ANY REASON WHATSOEVER.

File History

2013-10-28, David H. (DH):

Initial version