please dont rip this site

PIC Microcontroler based Keyboard

Mike McLaren's 'debounce', 'beep', and 'toggle' using vertical counters

This example ISR code features a switch press 'beep' function and supports standard "momentary" and "toggle" emulation switch types using standard normally-open push button switches. I often use "toggle" switch emulation for lighted switches (push to toggle from off-to-on and push to toggle from on-to-off).

;******************************************************************
;
;  Mike McLaren's "debounce" vertical counter example ISR code
;  based on concepts/examples from Jonny Doin and Scott Dattalo
;
;  <> process up to eight switches in parallel
;  <> eight independent 24.0-msec "debounce" vertical counters
;  <> debounced switch press audible feedback (beep or click)
;  <> momentary switch operation (test then clear a SWITCH bit)
;  <> toggle switch emulation (push to toggle a SWITCH bit from
;     off-to-on or from on-to-off) perfect for lighted switches
;
;  27 words/27 cycles (14-bit core), or
;  18 words/18 cycles without switch press beep code
;
;  setup the SWKEYS variable with "live" switch press data from
;  your switch input pins or your scanned switch matrix before
;  falling into this routine.  A '1' bit represents a 'pressed'
;  switch and a '0' bit represents a 'released' switch.
;
;  execute this code each 1.0-msec interrupt cycle
;
;
;  clear vertical counters for bouncing and steady-state switches
;
ISR_Sw
        movf    SWKEYS,W        ; live switch press data          |B0
        xorwf   SLATCH,W        ; debounced pressed switch latch  |B0
        andwf   VCBIT0,f        ;                                 |B0
        andwf   VCBIT1,f        ;                                 |B0
;
;  cyclic vertical counter algorithm.  vcmask is seeded with the
;  active switch mask and bn' is the previous state of bn before
;  the bit increment operation.
;
;  a switch is debounced or filtered after sampling it at the
;  same level through four vertical counts spanning 24.0-msecs
;
;    b0 ^= (vcmask)
;    b1 ^= (vcmask & b0')
;    b2 ^= (vcmask & b0' & b1')
;
;  Mike McLaren's "cumulative AND" vertical counter method
;
;    b0 ^= vcmask : vcmask &= bo'
;    b1 ^= vcmask : vcmask &= b1'
;    b2 ^= vcmask
;
        andwf   COLPOS,W        ; 8-msec 'column' prescaler       |B0
        movwf   VCMASK          ; seed "cumulative AND" mask      |B0
        xorwf   VCBIT0,f        ; b0 ^= vcmask                    |B0
        xorwf   VCBIT0,W        ; restore b0' in W                |B0
        andwf   VCMASK,W        ; vcmask &= b0'                   |B0
        movwf   VCMASK          ;                                 |B0
        xorwf   VCBIT1,f        ; b1 ^= vcmask                    |B0
        xorwf   VCBIT1,W        ; restore b1' in W                |B0
        andwf   VCMASK,W        ; vcmask &= b1'                   |B0
;
;  each '1' bit in the SLATCH variable represents a "debounced"
;  24.0-msec switch press (bit cleared when switch is released)
;
        xorwf   SLATCH,f        ; update debounced state latch    |B0
;
;  send a 32-msec short beep for new debounced switch presses
;
        andwf   SWKEYS,W        ; new debounced switch press?     |B0
        btfss   STATUS,Z        ; no, skip, else                  |B0
        bsf     BEEPER,5        ; send 32-msec short beep         |B0
;
;  toggle SWITCH flag bits for processing by the MAIN program
;
;  test SWITCH bits for emulated "toggle" switches.  test then
;  clear SWITCH bits for "momentary" switches.
;
        xorwf   SWITCH,f        ; toggle SWITCH bits for MAIN     |B0
;
;  advance ring counter prescaler (initialized value = 00000001)
;  for the next interrupt cycle
;
        rlf     COLPOS,W        ; advance column ring counter     |B0
        rlf     COLPOS,f        ;                                 |B0
;
;  beep (500-Hz tone with 1.0-msec interrupts)
;
        movf    BEEPER,W        ; beep timer set?                 |B0
        bz      ISR_Next        ; no, branch, else                |B0
        movf    GPIO,W          ; read port                       |B0
        xorlw   1<<Speaker      ;                                 |B0
        movwf   GPIO            ; toggle piezo speaker pin        |B0
        decf    BEEPER,f        ; decrement timer                 |B0
;
ISR_Next

See also:


file: /Techref/microchip/debouncebeeptoggleK8HL.htm, 4KB, , updated: 2006/10/9 13:53, local time: 2018/11/12 15:25,
TOP NEW HELP FIND: 
54.81.15.11:LOG IN

 ©2018 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions?
Please DO link to this page! Digg it! / MAKE! / 

<A HREF="http://www.piclist.com/techref/microchip/debouncebeeptoggleK8HL.htm"> PIC Keyboard debounce beep toggle</A>

After you find an appropriate page, you are invited to your to this massmind site! (posts will be visible only to you before review) Just type in the box and press the Post button. (HTML welcomed, but not the <A tag: Instead, use the link box to link to another page. A tutorial is available Members can login to post directly, become page editors, and be credited for their posts.


Link? Put it here: 
if you want a response, please enter your email address: 
Attn spammers: All posts are reviewed before being made visible to anyone other than the poster.
Did you find what you needed?

  PICList 2018 contributors:
o List host: MIT, Site host massmind.org, Top posters @20181112 RussellMc, Van Horn, David, Sean Breheny, David C Brown, Isaac M. Bavaresco, Neil, Bob Blick, AB Pearce - UKRI STFC, John Gardner, Harold Hallikainen,
* Page Editors: James Newton, David Cary, and YOU!
* Roman Black of Black Robotics donates from sales of Linistep stepper controller kits.
* Ashley Roll of Digital Nemesis donates from sales of RCL-1 RS232 to TTL converters.
* Monthly Subscribers: Gregg Rew. on-going support is MOST appreciated!
* Contributors: Richard Seriani, Sr.
 

Welcome to www.piclist.com!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  .