Can someone explain the API available in tivaware/driverlib/qei.h :
extern void QEIVelocityConfigure(uint32_t ui32Base, uint32_t ui32PreDiv,
uint32_t ui32Period);
what is the ui32Period here?
I wrote a simple program to calculate the position, direction of motion and velocity of a motor:
/*!
* @author Yash Bansod
* @date 26th September 2017
*
* @brief Quadrature Encoder
* @details The program interfaces the quadrature encoder peripheral to get the position
* and velocity information of a encoded DC motor.
* @note The tm4c123ghpm_startup_ccs.c contains the vector table for the
* microcontroller. It was modified to execute the specified ISR on
* PortF Interrupts.
*/
/* ----------------------- Include Files --------------------- */
#include <stdint.h> // Library of Standard Integer Types
#include <stdbool.h> // Library of Standard Boolean Types
#include "inc/tm4c123gh6pm.h" // Definitions for interrupt and register assignments on Tiva C
#include "inc/hw_memmap.h" // Macros defining the memory map of the Tiva C Series device
#include "inc/hw_types.h" // Defines common types and macros
#include "inc/hw_gpio.h" // Defines Macros for GPIO hardware
#include "inc/hw_qei.h" // Macros used when accessing the QEI hardware
#include "driverlib/debug.h" // Macros for assisting debug of the driver library
#include "driverlib/sysctl.h" // Defines and macros for System Control API of DriverLib
#include "driverlib/interrupt.h" // Defines and macros for NVIC Controller API of DriverLib
#include "driverlib/gpio.h" // Defines and macros for GPIO API of DriverLib
#include "driverlib/pin_map.h" // Mapping of peripherals to pins for all parts
#include "driverlib/rom.h" // Defines and macros for ROM API of driverLib
#include "driverlib/qei.h" // Prototypes for the Quadrature Encoder Driver
/* ----------------------- Global Variables --------------------- */
volatile uint32_t ui32Qei1Pos; // Variable to store the position of QEI1
volatile int32_t i32Qei1Dir; // Variable to store the direction of QEI1
volatile uint32_t ui32Qei1Vel; // Variable to store the velocity of QEI1
/* ----------------------- Function Prototypes --------------------- */
/* ----------------------- Main Program --------------------- */
int main(void){
// Set the System clock to 80MHz and the PWM Module clock to 1.25 MHz
ROM_SysCtlClockSet(SYSCTL_SYSDIV_2_5 |SYSCTL_USE_PLL |SYSCTL_OSC_MAIN |SYSCTL_XTAL_16MHZ);
// Enable the clock for peripherals PortD and QEI1
ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_QEI1);
ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOC);
// Configure the PC4, PC5, PC6 for QEI signals
ROM_GPIOPinTypeQEI(GPIO_PORTC_BASE, GPIO_PIN_5 | GPIO_PIN_6);
ROM_GPIOPinConfigure(GPIO_PC5_PHA1);
ROM_GPIOPinConfigure(GPIO_PC6_PHB1);
// Configure the QEI1 to increment for both PhA and PhB for quadrature input with 2400 PPR
ROM_QEIConfigure(QEI1_BASE, QEI_CONFIG_CAPTURE_A_B | QEI_CONFIG_QUADRATURE, 2400);
ROM_QEIVelocityConfigure(QEI1_BASE, QEI_VELDIV_1, 10000);
ROM_QEIVelocityEnable(QEI1_BASE);
// Enable the QEI1
ROM_QEIEnable(QEI1_BASE);
while (1){
ui32Qei1Pos = ROM_QEIPositionGet(QEI1_BASE);
i32Qei1Dir = ROM_QEIDirectionGet(QEI1_BASE);
ui32Qei1Vel = ROM_QEIVelocityGet(QEI1_BASE);
}
}
/* ----------------------- Function Definition --------------------- */
In what terms am I getting the Velocity here? Is it directly converted to RPM or is it in form of ticks?
