EncoderCounter.cpp

00001 /*
00002  * EncoderCounter.cpp
00003  * Copyright (c) 2017, ZHAW
00004  * All rights reserved.
00005  */
00006 
00007 #include "EncoderCounter.h"
00008 
00009 using namespace std;
00010 
00011 /**
00012  * Creates and initializes the driver to read the quadrature
00013  * encoder counter of the STM32 microcontroller.
00014  * @param a the input pin for the channel A.
00015  * @param b the input pin for the channel B.
00016  */
00017 EncoderCounter::EncoderCounter(PinName a, PinName b) {
00018     
00019     // check pins
00020     
00021     if ((a == PA_6) && (b == PC_7)) {
00022         
00023         // pinmap OK for TIM3 CH1 and CH2
00024         
00025         TIM = TIM3;
00026         
00027         // configure reset and clock control registers
00028         
00029         RCC->AHB1ENR |= RCC_AHB1ENR_GPIOCEN;    // manually enable port C (port A enabled by mbed library)
00030         
00031         // configure general purpose I/O registers
00032         
00033         GPIOA->MODER &= ~GPIO_MODER_MODER6;     // reset port A6
00034         GPIOA->MODER |= GPIO_MODER_MODER6_1;    // set alternate mode of port A6
00035         GPIOA->PUPDR &= ~GPIO_PUPDR_PUPDR6;     // reset pull-up/pull-down on port A6
00036         GPIOA->PUPDR |= GPIO_PUPDR_PUPDR6_1;    // set input as pull-down
00037         GPIOA->AFR[0] &= ~(0xF << 4*6);         // reset alternate function of port A6
00038         GPIOA->AFR[0] |= 2 << 4*6;              // set alternate funtion 2 of port A6
00039         
00040         GPIOC->MODER &= ~GPIO_MODER_MODER7;     // reset port C7
00041         GPIOC->MODER |= GPIO_MODER_MODER7_1;    // set alternate mode of port C7
00042         GPIOC->PUPDR &= ~GPIO_PUPDR_PUPDR7;     // reset pull-up/pull-down on port C7
00043         GPIOC->PUPDR |= GPIO_PUPDR_PUPDR7_1;    // set input as pull-down
00044         GPIOC->AFR[0] &= ~0xF0000000;           // reset alternate function of port C7
00045         GPIOC->AFR[0] |= 2 << 4*7;              // set alternate funtion 2 of port C7
00046         
00047         // configure reset and clock control registers
00048         
00049         RCC->APB1RSTR |= RCC_APB1RSTR_TIM3RST;  //reset TIM3 controller
00050         RCC->APB1RSTR &= ~RCC_APB1RSTR_TIM3RST;
00051         
00052         RCC->APB1ENR |= RCC_APB1ENR_TIM3EN;     // TIM3 clock enable
00053         
00054     } else if ((a == PB_6) && (b == PB_7)) {
00055         
00056         // pinmap OK for TIM4 CH1 and CH2
00057         
00058         TIM = TIM4;
00059         
00060         // configure reset and clock control registers
00061         
00062         RCC->AHB1ENR |= RCC_AHB1ENR_GPIOBEN;    // manually enable port B (port A enabled by mbed library)
00063         
00064         // configure general purpose I/O registers
00065         
00066         GPIOB->MODER &= ~GPIO_MODER_MODER6;     // reset port B6
00067         GPIOB->MODER |= GPIO_MODER_MODER6_1;    // set alternate mode of port B6
00068         GPIOB->PUPDR &= ~GPIO_PUPDR_PUPDR6;     // reset pull-up/pull-down on port B6
00069         GPIOB->PUPDR |= GPIO_PUPDR_PUPDR6_1;    // set input as pull-down
00070         GPIOB->AFR[0] &= ~(0xF << 4*6);         // reset alternate function of port B6
00071         GPIOB->AFR[0] |= 2 << 4*6;              // set alternate funtion 2 of port B6
00072         
00073         GPIOB->MODER &= ~GPIO_MODER_MODER7;     // reset port B7
00074         GPIOB->MODER |= GPIO_MODER_MODER7_1;    // set alternate mode of port B7
00075         GPIOB->PUPDR &= ~GPIO_PUPDR_PUPDR7;     // reset pull-up/pull-down on port B7
00076         GPIOB->PUPDR |= GPIO_PUPDR_PUPDR7_1;    // set input as pull-down
00077         GPIOB->AFR[0] &= ~0xF0000000;           // reset alternate function of port B7
00078         GPIOB->AFR[0] |= 2 << 4*7;              // set alternate funtion 2 of port B7
00079         
00080         // configure reset and clock control registers
00081         
00082         RCC->APB1RSTR |= RCC_APB1RSTR_TIM4RST;  //reset TIM4 controller
00083         RCC->APB1RSTR &= ~RCC_APB1RSTR_TIM4RST;
00084         
00085         RCC->APB1ENR |= RCC_APB1ENR_TIM4EN;     // TIM4 clock enable
00086         
00087     } else {
00088         
00089         printf("pinmap not found for peripheral\n");
00090     }
00091     
00092     // configure general purpose timer 3 or 4
00093     
00094     TIM->CR1 = 0x0000;          // counter disable
00095     TIM->CR2 = 0x0000;          // reset master mode selection
00096     TIM->SMCR = TIM_SMCR_SMS_1 | TIM_SMCR_SMS_0; // counting on both TI1 & TI2 edges
00097     TIM->CCMR1 = TIM_CCMR1_CC2S_0 | TIM_CCMR1_CC1S_0;
00098     TIM->CCMR2 = 0x0000;        // reset capture mode register 2
00099     TIM->CCER = TIM_CCER_CC2E | TIM_CCER_CC1E;
00100     TIM->CNT = 0x0000;          // reset counter value
00101     TIM->ARR = 0xFFFF;          // auto reload register
00102     TIM->CR1 = TIM_CR1_CEN;     // counter enable
00103 }
00104 
00105 EncoderCounter::~EncoderCounter() {}
00106 
00107 /**
00108  * Resets the counter value to zero.
00109  */
00110 void EncoderCounter::reset() {
00111     
00112     TIM->CNT = 0x0000;
00113 }
00114 
00115 /**
00116  * Resets the counter value to a given offset value.
00117  * @param offset the offset value to reset the counter to.
00118  */
00119 void EncoderCounter::reset(short offset) {
00120     
00121     TIM->CNT = -offset;
00122 }
00123 
00124 /**
00125  * Reads the quadrature encoder counter value.
00126  * @return the quadrature encoder counter as a signed 16-bit integer value.
00127  */
00128 short EncoderCounter::read() {
00129     
00130     return (short)(-TIM->CNT);
00131 }
00132 
00133 /**
00134  * The empty operator is a shorthand notation of the <code>read()</code> method.
00135  */
00136 EncoderCounter::operator short() {
00137     
00138     return read();
00139 }