I also use the GPT Timer for simple PWM generation. I know the question has been answered, but its another approach that works for fast results...
You can also examine my NXP PWM generator source on Github
https://github.com/solaraeng/NXP_M4_PWM
Here is the .pdf description :Readme_PWM.pdf
An Youtube of it in action is here : NXP FreeRTOS PWM modulator/LED current driver on NXP imx7 via GPT on Toradex ASTER - YouTube
(I wrote it for Toradex Colibri on ASTER) but I will also port it for NXP Sabre, it uses a technique, which is much simpler and uses the NXP GPT Timer to generate PWM by alternating phases...It takes a little bit of intuition to use, but it only requires you enter your timing characteristics and number of steps inside each phase. I might use this to create a better driver for motor control. The code goes as follows :
/*
* Copyright (c) 2015, Freescale Semiconductor, Inc.
* All rights reserved.
***************************************************************************************
* Project - mx7_colibri_m4_PWM_imx_demo (PWM Modulator)
* Created by : Mario Ghecea
* Solara Engineering (solaraeng@gmail.com)
* 6/29/2019
* Purpose - To facilitate a scalable and programmable PWM algorithm within FreeRTOS
* utilizing any number of dividing steps (1-n) for smoothness and PWM resolution
* Only one generic timer (GPT) is used as counter for each alternating phase step...
* This could be used as a generic LED driver, contrast for a display and perhaps
* motor control through expansion.
* If you reuse or distribute for your purpose please keep this header...
*****************************************************************************************
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* o Redistributions of source code must retain the above copyright notice, this list
* of conditions and the following disclaimer.
*
* o Redistributions in binary form must reproduce the above copyright notice, this
* list of conditions and the following disclaimer in the documentation and/or
* other materials provided with the distribution.
*
* o Neither the name of Freescale Semiconductor, Inc. nor the names of its
* contributors may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "FreeRTOS.h"
#include "task.h"
#include "board.h"
#include "debug_console_imx.h"
#include "gpio_ctrl.h"
#include "hw_timer.h"
#define PWM_MIN (0.1f) // Lets assume 10% phase increases
#define PWM_MAX (1.0f) // Lets assume your phase max at 100%
#define PWM_FREQ_DIVIDER 1 // Your PWM period frequency divider in milliseconds (1/PWM_FREQ_DIVIDER) - LED Bink Interval
#define PWM_STEPS_PER_PHASE 20 // Increment PWM_STEPS_PER_PHASE for a higher resolution (Above 20 it suddenly glitches)
#define PWM_RESOLUTION_COUNTER (1000/(PWM_FREQ_DIVIDER * PWM_STEPS_PER_PHASE)) // Value in ms per phase
static volatile uint32_t blinkingIntervalHigh = PWM_RESOLUTION_COUNTER;
static volatile uint32_t blinkingIntervalLow = PWM_RESOLUTION_COUNTER;
static volatile float pwm = PWM_MIN;
static volatile bool start = true;
void SyncPWM();
void Resync();
/******************************************************************************
*
* Function Name: ToggleTask
* Comments: this task is used to turn toggle on/off LED.
* This task has the effect of staring on cue so it will sync the phases
* correctly based on start signal from Phase Synchronizer (SwitchTask).
*
******************************************************************************/
void ToggleTask(void *pvParameters)
{
while (true)
{
if (blinkingIntervalHigh != 0 && start == true)
{
// If we have been signaled to start, lets sync the PWM phase
SyncPWM();
// Process PWM Phase High
GPIO_Ctrl_ToggleLed(true);
/* Use Hardware timer to get accurate delay */
Hw_Timer_Delay(blinkingIntervalHigh);
// Process PWM Phase Low
GPIO_Ctrl_ToggleLed(false);
Hw_Timer_Delay(blinkingIntervalLow);
}
}
}
// Sync PWM Block - Phase Increment
void SyncPWM()
{
blinkingIntervalHigh = PWM_RESOLUTION_COUNTER * pwm ;
blinkingIntervalLow = PWM_RESOLUTION_COUNTER * (1.0f - pwm);
pwm += (0.5f / PWM_STEPS_PER_PHASE);
Resync();
}
void Resync()
{
if (pwm >= PWM_MAX)
{
pwm = PWM_MIN;
}
}
/******************************************************************************
*
* Function Name: main
* Comments: main function, toggle LED and switch the blinking frequency by key.
*
******************************************************************************/
int main(void)
{
/* Initialize board specified hardware. */
hardware_init();
Hw_Timer_Init();
GPIO_Ctrl_Init();
PRINTF("\n\r================= PWM Blinking Demo ==================\n\r");
/* Create a the APP main task. */
xTaskCreate(ToggleTask, "Toggle Task", configMINIMAL_STACK_SIZE,
NULL, tskIDLE_PRIORITY+1, NULL);
/* Start FreeRTOS scheduler. */
vTaskStartScheduler();
/* should never reach this point. */
while (true);
}
/*******************************************************************************
* EOF
******************************************************************************/
