The TM4C123GH6PM microcontroller contains two PWM modules, each module has four PWM generator blocks and a control block. Each PWM generator block produces two PWM signals, GENA and GENB. Both PWM output signals share the same PWM timer and frequency and can either be programmed with independent actions or as a single pair of complementary signals.

Each PWM generator block has the following features:

• One 16-bit counter
  • Runs in Down or Up/Down mode
  • PWM output frequency controlled by a 16-bit LOAD value
  • Load value updates can be synchronized
  • Produces output signals at zero and LOAD value
• Two PWM comparators (CMPA, CMPB)
  • Comparator value updates can be synchronized
  • Produces PWM output signals on match
• PWM signal generator
  • Output PWM signal is constructed based on actions taken as a result of the counter and PWM comparator output signals
  • Produces two independent PWM signals (GENA, GENB)

The m is PWM Module number, g is the PWM Generator number, and n is the GPIO Port name.

The following example code will configure the left-aligned PWM signal on PF1, which is connected with an onboard Red LED.

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>
 
#include "TM4C123GH6PM.h"
// #include "MyDefines.h"  // Your Definition Header File
 
void Setup_PWM(void);
void Setup_GPIO(void);

int main()
{
    Setup_PWM();
    Setup_GPIO(); 

    while(1){
        // Place your application code here
 
    }
}
//------------------------------------------------------------------------------ 
void Setup_PWM(void)
{
    // 1. Enable Clock for PWM Modules
    SYSCTL->RCGCPWM |= 0x02;
    while((SYSCTL->PRPWM & 0x02) != 0x02 ){};
    // 2. Enable and Setup Clock Divider for PWM Timer
    SYSCTL->RCC |= (1 << 20);       // RCC[20]=1:USEPWMDIV
    SYSCTL->RCC &= ~(0x7 << 17);    // RCC[19:17]=000 PWMDIV
    SYSCTL->RCC |= (0x4 << 17);     // RCC[19:17]=0x4 divider=/32
    // 3. Disable PWM Generator and Setup the Timer Counting Mode
    PWM1->_2_CTL = 0x00;            // Disable PWM Generator, and set to count-down mode
    // 4. Configure LOAD (Period), CMP (Duty), GEN (PWM Mode) values
    PWM1->_2_LOAD = 50000;          // Setup the period of the PWM signal
    PWM1->_2_CMPB = 50000-2250;     // Setup the initial duty cycle
    PWM1->_2_GENB = (0x02 << 10 ) | (0x03 <<2); // ACTCMPBD=ActLow ACTLOAD=ActHigh
    // 5. Enable PWM Generator
    PWM1->_2_CTL |= 0x01;
    // 6. Enable PWM Output
    PWM1->ENABLE = (1 << 5);        // Enable PWM5
}
void Setup_GPIO(void)
{
    // GPIO Initialization and Configuration
    // 1. Enable Clock to the GPIO Modules (SYSCTL->RCGCGPIO |= (_PORTs);)
    SYSCTL->RCGCGPIO |= (_PORTs); |= ( );
    // allow time for clock to stabilize (SYSCTL->PRGPIO)
    while((SYSCTL->PRGPIO & (  )) != (  )){};
 
    // 2. Unlock GPIO only PD7, PF0 on TM4C123G; PD7, PE7 on TM4C1294 (GPIOx->LOCK = 0x4C4F434B; and GPIOx->CR = _PINs;)
    // 3. Set Analog Mode Select bits for each Port (GPIOx->AMSEL = _PINs; 0=digital, 1=analog)
    // 4. Set Port Control Register for each Port (GPIOx->PCTL = PMCn << _PTCL_PINn, check the PCTL table)
    // 5. Set Alternate Function Select bits for each Port (GPIOx->AFSEL = _PINs; 0=regular I/O, 1=PCTL peripheral)
    // 6. Set Output pins for each Port (Direction of the Pins: GPIOx->DIR = _PINs; 0=input, 1=output)
    // 7. Set PUR bits for internal pull-up, PDR for pull-down reg, ODR for open drain (0: disable, 1=enable)
    // 8. Set Digital ENable register on all GPIO pins (GPIOx->DEN = _PINs; 0=disable, 1=enable)
}

The TM4C1294NCPDT microcontroller contains one PWM module, with four PWM generator blocks and a control block, for a total of 8 PWM outputs.

Each PWM generator block produces two PWM signals that share the same PWM timer and frequency and can either be programmed with independent actions or as a single pair of complementary signals. The output signals, GENA and GENB, of the PWM generation blocks are managed by the output control block before being passed to the device pins.

Each PWM generator block has the following features:

• One 16-bit counter
  • Runs in Down or Up/Down mode
  • PWM Output frequency controlled by a 16-bit LOAD value
  • Load value updates can be synchronized
  • Produces output signals at zero and load value
• Two PWM comparators (CMPA, CMPB)
  • Comparator value updates can be synchronized
  • Produces output signals on match
• PWM signal generator
  • Output PWM signal is constructed based on actions taken as a result of the counter and PWM comparator output signals
  • Produces two independent PWM signals

The following steps show how to initialize PWM Generator

The m is the PWM Module number, g is the PWM Generator number, and n is the GPIO Port name.

The following example code will configure the left-aligned PWM signal on PF0, which is connected with an onboard Green LED.

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>
 
#include "TM4C1294NCPDT.h"
// #include "MyDefines.h"  // Your Definition Header File
 
void Setup_PWM(void);
void Setup_GPIO(void);

int main()
{
    Setup_PWM();
    Setup_GPIO(); 

    while(1){
        // Place your application code here
 
    }
}
//------------------------------------------------------------------------------ 
void Setup_PWM(void)
{
    // 1. Enable Clock for PWM Module
    SYSCTL->RCGCPWM |= 0x01;
    while((SYSCTL->PRPWM & 0x01) != 0x01 ){};
    // 2. Enable and Setup Clock Divider for PWM Timer
    PWM0->CC  = (1 << 8);           // CC[8]:USEPWMDIV
    PWM0->CC &= ~0x7;               // CC[2:0]=000 PWMDIV
    PWM0->CC |= (0x2);              // CC[2:0]=0x2 divider = /8
    // 3. Disable PWM Generator and Setup the Timer counting mode
    PWM0->_0_CTL = 0x00;            // Disable PWM Generator, and set to count down mode
    // 4. Configure LOAD (Period), CMP (Duty), GEN (PWM Mode) values
    PWM0->_0_LOAD = 50000;          // Setup the period of the PWM signal
    PWM0->_0_CMPB = 50000-2250;     // Setup the initial duty cycle
    PWM0->_0_GENA = (0x02 << 6 ) | (0x03 <<2); // ACTCMPAD=ActLow ACTLOAD=ActHigh
    // 5. Enable PWM Generator
    PWM0->_0_CTL |= 0x01;           // Enable PWM Generator
    // 6. Enable PWM Output
    PWM0->ENABLE = 0x01;            // Enable PWM0
}
void Setup_GPIO(void)
{
    // GPIO Initialization and Configuration
    // 1. Enable Clock to the GPIO Modules (SYSCTL->RCGCGPIO |= (_PORTs);)
    SYSCTL->RCGCGPIO |= (_PORTs); |= ( );
    // allow time for clock to stabilize (SYSCTL->PRGPIO)
    while((SYSCTL->PRGPIO & (  )) != (  )){};
 
    // 2. Unlock GPIO only PD7, PF0 on TM4C123G; PD7, PE7 on TM4C1294 (GPIOx->LOCK = 0x4C4F434B; and GPIOx->CR = _PINs;)
    // 3. Set Analog Mode Select bits for each Port (GPIOx->AMSEL = _PINs;  0=digital, 1=analog)
    // 4. Set Port Control Register for each Port (GPIOx->PCTL = PMCn << _PTCL_PINn, check the PCTL table)
    // 5. Set Alternate Function Select bits for each Port (GPIOx->AFSEL = _PINs;  0=regular I/O, 1=PCTL peripheral)
    // 6. Set Output pins for each Port (Direction of the Pins: GPIOx->DIR = _PINs;  0=input, 1=output)
    // 7. Set PUR bits (internal Pull-Up Resistor), PDR (Pull-Down Resistor), ODR (Open Drain) for each Port (0: disable, 1=enable)
    // 8. Set Digital ENable register on all GPIO pins (GPIOx->DEN = _PINs; 0=disable, 1=enable)
}