View source for PIC32MX: Encoder Motor Control

==Available Pins==
The PIC32MX460F512L has 5 available external timer / counter pins denoted TXCK on the pin list, where x is from 1 to 5. 
Unfortunately, the PIC32MX440F512H has only 1 available external counter (T1CK), so this cannot be used for quadrature encoder using the external counter pins. 
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==Quadrature Encoder Example==
This section details how to set up quadrature encoder with the PIC32MX460F512L and the LS7083. 

===Sample Code===

 /*
 QuadratureHard.c 
 
 The PIC32MX460F512L has 5 available external timer / counter pins denoted TXCK on the pin list, 
 where x is from 1 to 5. Unfortunately, the PIC32MX440F512H has only 1 available external counter (T1CK), 
 so this PIC cannot be used for quadrature encoder. The NU32 board uses PIC32MX460F512L. 
 
 This code is based on the QuadratureHard.c for the 8-bit PICS.
 Quadrature based on Hardware requires two timers to count up-counts and down-counts. 
 
 PWM uses Timer 2 or Timer 3, therefore, we are going to use Timer 4 and Timer 5 for this code.
 Timer 4 is T4CK/RC3 and Timer 5 is SDI1/T5CK/RC4.
 
 LS7083 chip decodes quadrature A&B signals into up&down pulses for these two timers
 The software version doesn't use up timers but this hardware version is arbitrarily fast
 */
 
  #include "HardwareProfile.h"
  
  signed int bigcount = 0; 	// set encoder value initially to zero, it can go + or -
  						 	// 32 bit number
  short count0, count1; 		// 16 bit number
  short last0 = 0, last1 = 0; // 16 bit number
  
  int main(void) {
  	
  	// Configure the system performance
 	SYSTEMConfigPerformance(SYS_FREQ);
 	
 	mInitAllLEDs();
 
 	
 	// Must enable glocal interrupts - in this case, we are using multi-vector mode
     INTEnableSystemMultiVectoredInt();
 	
      // init Timer4 and Timer5 mode and periods (PR4, PR5)
 	OpenTimer4( T4_ON | T4_PS_1_1 | T4_SOURCE_EXT, 0xFFFF);
 	OpenTimer5( T5_ON | T5_PS_1_1 | T5_SOURCE_EXT, 0xFFFF);
   	
 	while (1) {                
 		count0 = ReadTimer4();  // in your routine this must be done at least every 32000
 								// encoder counts to avoid rollover ambiguity
 		count1 = ReadTimer5(); 	
 
 		bigcount += count0 - last0; // add on the recent up-counts, since the last time
 	
 		if (count0 < last0)
 		{
 			bigcount += 65536; 		// count0 only increments, so if it got lower 
 	 					   		//it must have rolled over
 		}
 
 		last0 = count0;
 
 		bigcount -= count1 - last1; // we're not worrying about rollover of the 32 bit bigcount total
 	
 		if (count1 < last1)
 		{
 			bigcount -= 65536;
 		}
 	
 		last1 = count1; 
 	      
                 // Put other code here to display (RS232 works nice)
 		}
 }

==Associated Circuitry==

This Circuit is based off the HEDS5500 encoder, LS7083 quadrature, and PIC32MX460F512L.

[[Media:Quad_Encoder_PIC32_Circuit.pdf]]