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Dependencies:   PinDetect mbed

main.cpp@1:5c21ef62c975, 2022-01-13 (annotated)

Committer:
4180_1
Date:
Thu Jan 13 14:29:07 2022 +0000
Revision:
1:5c21ef62c975
Parent:
0:3eea8ad2dbbc 
ver 1.1 put lookup table in Flash using const; Added a few more comments

Who changed what in which revision?

UserRevisionLine numberNew contents of line
4180_1 0:3eea8ad2dbbc 1 #include "mbed.h"
4180_1 0:3eea8ad2dbbc 2 #include "PinDetect.h"
4180_1 0:3eea8ad2dbbc 3 //See http://makeatronics.blogspot.com/2013/02/efficiently-reading-quadrature-with.html
4180_1 0:3eea8ad2dbbc 4 //for a detailed explanation of the RPG encoder counting algorithm
4180_1 0:3eea8ad2dbbc 5 //uses Sparkfun RPG with RGB led on breakout board (#15141,11722,10597)
4180_1 0:3eea8ad2dbbc 6 //place RPG PCB across a breadboard power bus strip for easier pin hookup!
4180_1 0:3eea8ad2dbbc 7 InterruptIn RPG_A(p14,PullUp);//encoder A and B pins/bits use interrupts
4180_1 0:3eea8ad2dbbc 8 InterruptIn RPG_B(p15,PullUp);
4180_1 0:3eea8ad2dbbc 9 PinDetect RPG_PB(p16); //encode pushbutton switch "SW" on PCB
4180_1 0:3eea8ad2dbbc 10 //PWM setup for RGB LED in enocder
4180_1 0:3eea8ad2dbbc 11 PwmOut red(p21);//"R" pin
4180_1 0:3eea8ad2dbbc 12 PwmOut blue(p22);//"G" pin
4180_1 0:3eea8ad2dbbc 13 PwmOut green(p23);//"B" pin
4180_1 0:3eea8ad2dbbc 14 //Note: also tie RPG PCB "C" pin to ground, "+" pin to 3.3
4180_1 0:3eea8ad2dbbc 15 //mbed status leds
4180_1 0:3eea8ad2dbbc 16 DigitalOut ledPB(LED1);
4180_1 0:3eea8ad2dbbc 17 DigitalOut red_adjust_mode(LED2);
4180_1 0:3eea8ad2dbbc 18 DigitalOut green_adjust_mode(LED3);
4180_1 0:3eea8ad2dbbc 19 DigitalOut blue_adjust_mode(LED4);
4180_1 0:3eea8ad2dbbc 20 //Serial pc(USBTX,USBRX);
4180_1 0:3eea8ad2dbbc 21 volatile int old_enc = 0;
4180_1 0:3eea8ad2dbbc 22 volatile int new_enc = 0;
4180_1 0:3eea8ad2dbbc 23 volatile int enc_count = 0;
4180_1 0:3eea8ad2dbbc 24 //Instead of a slow 16 case statement use a faster table lookup of truth table
4180_1 1:5c21ef62c975 25 //index table with (previous encoder AB value<<2 | current current encoder AB value)
4180_1 1:5c21ef62c975 26 //to find -1(CCW),0,or 1(CW) change in count each time a bit changes state
4180_1 1:5c21ef62c975 27 //Always want Interrupt routines to run fast!
4180_1 1:5c21ef62c975 28 //const puts data in read only Flash instead of RAM
4180_1 1:5c21ef62c975 29 const int lookup_table[] = {0,-1,1,0,1,0,0,-1,-1,0,0,1,0,1,-1,0};
4180_1 0:3eea8ad2dbbc 30 //Encoder bit change interrupt service routine
4180_1 1:5c21ef62c975 31 //called whenever one of the two A,B encoder bits change state
4180_1 0:3eea8ad2dbbc 32 void Enc_change_ISR(void)
4180_1 0:3eea8ad2dbbc 33 {
4180_1 1:5c21ef62c975 34 new_enc = RPG_A<<1 | RPG_B;//current encoder bits
4180_1 1:5c21ef62c975 35 //check truth table for -1,0 or +1 added to count
4180_1 0:3eea8ad2dbbc 36 enc_count = enc_count + lookup_table[old_enc<<2 | new_enc];
4180_1 0:3eea8ad2dbbc 37 old_enc = new_enc;
4180_1 0:3eea8ad2dbbc 38 }
4180_1 1:5c21ef62c975 39 //debounced RPG pushbutton switch callback
4180_1 0:3eea8ad2dbbc 40 void PB_callback(void)
4180_1 0:3eea8ad2dbbc 41 {
4180_1 0:3eea8ad2dbbc 42 ledPB= !ledPB;
4180_1 0:3eea8ad2dbbc 43 }
4180_1 0:3eea8ad2dbbc 44 int main()
4180_1 0:3eea8ad2dbbc 45 {
4180_1 0:3eea8ad2dbbc 46 //turn off built-in RPG encoder RGB led
4180_1 1:5c21ef62c975 47 red = 1.0;//PWM value 1.0 is "off", 0.0 is full "on"
4180_1 0:3eea8ad2dbbc 48 green = 1.0;
4180_1 0:3eea8ad2dbbc 49 blue = 1.0;
4180_1 0:3eea8ad2dbbc 50 //current color adjust set to red
4180_1 0:3eea8ad2dbbc 51 red_adjust_mode = 1;
4180_1 0:3eea8ad2dbbc 52 //debounce RPG center pushbutton
4180_1 0:3eea8ad2dbbc 53 RPG_PB.mode(PullDown);
4180_1 0:3eea8ad2dbbc 54 RPG_PB.attach_deasserted(&PB_callback);
4180_1 0:3eea8ad2dbbc 55 RPG_PB.setSampleFrequency();
4180_1 0:3eea8ad2dbbc 56 // generate an interrupt on any change in either encoder bit (A or B)
4180_1 0:3eea8ad2dbbc 57 RPG_A.rise(&Enc_change_ISR);
4180_1 0:3eea8ad2dbbc 58 RPG_A.fall(&Enc_change_ISR);
4180_1 0:3eea8ad2dbbc 59 RPG_B.rise(&Enc_change_ISR);
4180_1 0:3eea8ad2dbbc 60 RPG_B.fall(&Enc_change_ISR);
4180_1 0:3eea8ad2dbbc 61 while (true) {
4180_1 0:3eea8ad2dbbc 62 // Scale/limit count to 0..100
4180_1 0:3eea8ad2dbbc 63 if (enc_count>100) enc_count = 100;
4180_1 0:3eea8ad2dbbc 64 if (enc_count<0) enc_count = 0;
4180_1 0:3eea8ad2dbbc 65 red = 1.0 - enc_count/100.0;
4180_1 0:3eea8ad2dbbc 66 // pc.printf("%D\n\r",enc_count);
4180_1 0:3eea8ad2dbbc 67 }
4180_1 0:3eea8ad2dbbc 68 }