Diff: main.cpp

Revision:

0:25c34018702c

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Mon Nov 17 19:17:21 2014 +0000
@@ -0,0 +1,62 @@
+#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);
+    }
+   
+       
+}
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