S32K144 FreeRTOS PWM configuration

cancel
Showing results for 
Search instead for 
Did you mean: 

S32K144 FreeRTOS PWM configuration

1,029 Views
jay_zhang
Contributor II

I want to control the rgb brightness in s32k144 dev board, run the example "ftm_pwm_s32k144" successfully, I can see the red light brightness changing.

While porting the code into my project(based on FreeRTOS), I config the FTM1 and add the code to initialize the pwm and call the function to change the duty cycle, but cannot see the brightness change, anyone can help me with my issue?

Attach the project as attachment file.

Labels (1)
0 Kudos
4 Replies

329 Views
solaraeng
Contributor I

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
******************************************************************************/

0 Kudos

329 Views
ovidiualexandru
NXP TechSupport
NXP TechSupport

Hello,


Seems like the FTM state structure is allocated on the stack, so its contents get invalidated after the prvSetupHardware function returns.


To fix this, in the rtos.c file, in function prvSetupHardware, at line 147: please move the ftmStateStruct declaration outside of the function body. This way it will be allocated in the .data section.

pastedImage_1.png
to

pastedImage_2.png

Best regards,

Ovidiu

329 Views
jay_zhang
Contributor II

Thansk Ovidiu,

It works

0 Kudos

329 Views
jay_zhang
Contributor II

Anyone can help me on this issue?

0 Kudos