Is there anyone recognize this source code?
#include "DSP281x_Device.h"
#include "f281xqep.h"
void F281X_EV1_QEP_Init(QEP *p)
{
EvaRegs.CAPCONA.all = QEP_CAP_INIT_STATE; // Set up capture units
EvaRegs.T2CON.all = QEP_TIMER_INIT_STATE; // Set up capture timer
EvaRegs.T2PR = 4*p->LineEncoder; // Init Timer 1 period Register
EvaRegs.EVAIFRC.bit.CAP3INT = 1; // Clear CAP3 flag
EvaRegs.EVAIMRC.bit.CAP3INT = 1; // Enable CAP3 Interrupt
EALLOW; // Enable EALLOW
GpioMuxRegs.GPAMUX.all |= 0x0700; // Set up the capture pins to primary functions
EDIS; // Disable EALLOW
}
void F281X_EV1_QEP_Calc(QEP *p)
{
int32 Tmp;
// Check the rotational direction
p->DirectionQep = 0x4000&EvaRegs.GPTCONA.all;
p->DirectionQep = p->DirectionQep>>14;
// Check the timer 2 counter for QEP
p->RawTheta = EvaRegs.T2CNT + p->CalibratedAngle;
// Compute the mechanical angle in Q15
Tmp = __qmpy32by16(p->MechScaler,p->RawTheta,31); // Q15 = Q30*Q0
p->MechTheta = (int16)(Tmp); // Q15 -> Q15
p->MechTheta &= 0x7FFF; // Wrap around 0x07FFF
// Compute the electrical angle in Q15
p->ElecTheta = p->PolePairs*p->MechTheta; // Q0*Q15 = Q15
p->ElecTheta &= 0x7FFF; // Wrap around 0x07FFF
}
void F281X_EV1_QEP_Isr(QEP *p)
{
p->QepCountIndex = EvaRegs.T2CNT; // Get the timer 2 counter for one mechanical revolution
EvaRegs.T2CNT = 0; // Reset the timer 2 counter
p->IndexSyncFlag = 0x00F0; // Set the index flag
}
What is the function of 'p'? and do i have to define it? all the source code have this 'p' but i still can't figure out what the function.
