
Demo program to read ABZ Quadrature Encoder in Hardware on the Nucleo F401RE
main.cpp
- Committer:
- Nigel945426
- Date:
- 2014-11-17
- Revision:
- 0:25c34018702c
File content as of revision 0:25c34018702c:
#include "mbed.h" // Hardware Quadrature Encoder ABZ for Nucleo F401RE // Output on debug port to host PC @ 9600 baud // // By Nigel Webb, November 2014 /* Connections PA_0 = Encoder A PA_1 = Encoder B PA_4 = Encoder Z */ InterruptIn ZPulse(PA_4) ; // Setup Interrupt for Z Pulse void EncoderInitialise(void) { // configure GPIO PA0 & PA1 as inputs for Encoder RCC->AHB1ENR |= 0x00000001; // Enable clock for GPIOA GPIOA->MODER |= GPIO_MODER_MODER0_1 | GPIO_MODER_MODER1_1 ; //PA0 & PA1 as Alternate Function /*!< GPIO port mode register, Address offset: 0x00 */ GPIOA->OTYPER |= GPIO_OTYPER_OT_0 | GPIO_OTYPER_OT_1 ; //PA0 & PA1 as Inputs /*!< GPIO port output type register, Address offset: 0x04 */ GPIOA->OSPEEDR |= GPIO_OSPEEDER_OSPEEDR0 | GPIO_OSPEEDER_OSPEEDR1 ; // Low speed /*!< GPIO port output speed register, Address offset: 0x08 */ GPIOA->PUPDR |= GPIO_PUPDR_PUPDR0_1 | GPIO_PUPDR_PUPDR1_1 ; // Pull Down /*!< GPIO port pull-up/pull-down register, Address offset: 0x0C */ GPIOA->AFR[0] |= 0x00000011 ; // AF01 for PA0 & PA1 /*!< GPIO alternate function registers, Address offset: 0x20-0x24 */ GPIOA->AFR[1] |= 0x00000000 ; // /*!< GPIO alternate function registers, Address offset: 0x20-0x24 */ // configure TIM2 as Encoder input RCC->APB1ENR |= 0x00000001; // Enable clock for TIM2 TIM2->CR1 = 0x0001; // CEN(Counter ENable)='1' < TIM control register 1 TIM2->SMCR = 0x0003; // SMS='011' (Encoder mode 3) < TIM slave mode control register TIM2->CCMR1 = 0xF1F1; // CC1S='01' CC2S='01' < TIM capture/compare mode register 1 TIM2->CCMR2 = 0x0000; // < TIM capture/compare mode register 2 TIM2->CCER = 0x0011; // CC1P CC2P < TIM capture/compare enable register TIM2->PSC = 0x0000; // Prescaler = (0+1) < TIM prescaler TIM2->ARR = 0xffffffff; // reload at 0xfffffff < TIM auto-reload register TIM2->CNT = 0x0000; //reset the counter before we use it } // Z Pulse routine void ZeroEncoderCount() { TIM2->CNT=0 ; //reset count to zero } int main() { EncoderInitialise() ; ZPulse.rise(&ZeroEncoderCount) ; //Setup Interrupt for rising edge of Z pulse ZPulse.mode(PullDown) ; // Set input as pull down unsigned int EncoderPosition ; while (true) { // Print Encoder Quadrature count to debug port every 0.5 seconds EncoderPosition = TIM2->CNT ; // Get current position from Encoder printf("Encoder Position %i\r\n", EncoderPosition); wait(0.5); } }