eecs 461 prelab 4 declarations for pwmc pwmc university of michigan eecs 461
embedded control systems pulse width modulation using flextimer module read
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EECS 461
Prelab 4
Due 02/04/2020
Declarations for pwm.c
/*
pwm.c
University of Michigan
EECS 461, Embedded Control Systems
Pulse-Width Modulation using FlexTimer Module
Read Chapter 45 in S32K144 User's Manual
Important sections:
45.4.2: Register Descriptions
45.5.7: Edge-Aligned PWM (EPWM) Mode
*/
#include "eecs461.h"
#include "pwm.h"
void setPWM(int submodule, int channel, int frequency, float dutyCycle)
{
uint16_t cthres;
uint16_t cmax;
float T = 1/frequency;
float Tc = 1/PWM_CLOCK_FREQ;
cmax = T/Tc - 1; /* fill in */
, cthres = dutyCycle*(cmax+1); /* fill in */
FTM_MODULE[submodule]->MOD = cmax;/* fill in */ /* Set the PWM
frequency */
FTM_MODULE[submodule]->CONTROLS[channel].CnV = cthres /* fill in */ /*
Set the PWM duty cycle */
}
2. Answer attached after code
3. initPWM
void initPWM(int submodule, int channel, int frequency, float dutyCycle)
{
uint16_t cmax;
float T = 1/frequency;
float Tc = 1/PWM_CLOCK_FREQ;
/* 45.4.3.2 - Status and Control (SC) */
FTM_MODULE[submodule]->SC = 0x00000000; /* Clear the status and control
register */
FTM_MODULE[submodule]->SC |= FTM_SC_CLKS(0b11); /* Select external
clock */
/* Enable the respective channel */
FTM_MODULE[submodule]->SC |= FTM_SC_PWMEN0(0b1);
/* Channel Control see S45.4.3.5 and Table 45-5 (S45.5.4) */
FTM_MODULE[submodule]->CONTROLS[channel].CnSC = 0; /* Clear the
register*/
FTM_MODULE[submodule]-> CONTROLS[channel].CnSC|= FTM_CnSC_MSB(1) ; /*
MSB : Edge Align PWM */
FTM_MODULE[submodule]-> CONTROLS[channel].CnSC|= FTM_CnSC_MSA(1) ; /*
MSA : Edge Align PWM */
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