please dont rip this site

PIC Micro Controller C Input / Output Routine

Quadrature Encoder ISR

by David Kott

struct RotaryEncoderStruct {
      int unused:4;  // RB[0:3]
      int A:1;   // RB4
      int B:1;   // RB5
      int unused2:2;  // RB6-7

struct RotaryEncoderStruct RotaryEncoder;

#pragma BYTE PORTB = 0x06

#pragma BYTE RotaryEncoder = 0x06 // Place structure right over PORTB at
location 0x06

USHORT g_usEncoderCount = 0;

#pragma INT_RB
PortBInterrupt (void)

      static BYTE OldPortB;
      BYTE byTemp;
      static struct RotaryEncoderStruct OldEncoder;

      if (OldPortB != (byTemp=(PORTB & 0x30))) {

      OldPortB = byTemp;

      if (RotaryEncoder.A == OldEncoder.A) {
     if (RotaryEncoder.B == RotaryEncoder.A)
      } else {
     OldEncoder.A = RotaryEncoder.A;
     if (RotaryEncoder.B == RotaryEncoder.A)


   // Handle more PORTB stuff here, like a button, or something.




See also:

file: /Techref/microchip/language/c/io/qenc-dk.htm, 2KB, , updated: 2019/10/19 12:20, local time: 2021/10/21 11:46,

 ©2021 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=""> PIC C I/O Routine - Quadrature Encoder ISR</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 a nice message (short messages are blocked as spam) 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 2021 contributors:
o List host: MIT, Site host, Top posters @20211021 Neil, Harold Hallikainen, Alan Pearce, RussellMc, Bob Blick, Allen Mulvey, Dwayne Reid, madscientistatlarge, Sean Breheny, Justin Richards,
* 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!