Ledc randomly invert PWM signal output #8306
Description
Board
ESP32 Dev module (Wroom-32)
Device Description
Wired on readboard
Hardware Configuration
RC servo / motor driver.
Version
v2.0.9
IDE Name
Arduino IDE
Operating System
Windows 10
Flash frequency
80Mhz
PSRAM enabled
yes
Upload speed
921600
Description
I'm working on a small library to drive DC and servo motor via ledc PWM output. To go deeper in timer management, I write it with ESP32 IDF regular syntax and structure. I've noticed that randomly, PWM output is inverted, regardless of the port use. I supposed a hardware trouble, but this problem happened with other ESP32 dev kit module.
Trouble was fixed by adding a GPIO.func_out_sel_cfg[SERVO_PIN].inv_sel = 0 on my code.
During my research to fix this problem, I noticed that the Espressif ESP32 IDF have a **output_invert flag**_ on its ledc_channel_config_t struct. I tried to implement it on my code, but Arduino ESP32 port seemed to miss this one and return me an error during compilation. I'm not a c expert programmer, but I suspect a non initialization of this variable by Arduino port who can cause this random problem ? Could you check that deeper in your code please.
Sketch
PWM setup code (cleaned for readability)
// create timer config structure
_timers_config[_pwmTimer] = new ledc_timer_config_t;
// seeding timer config parameters
_timers_config[_pwmTimer]->speed_mode = LEDC_HIGH_SPEED_MODE; // set timer mode
_timers_config[_pwmTimer]->freq_hz = pwmFreq; // set frequency of PWM signal
_timers_config[_pwmTimer]->timer_num = (ledc_timer_t)_pwmTimer; // set timer index
_timers_config[_pwmTimer]->clk_cfg = LEDC_AUTO_CLK; // set LEDC source clock
_timers_config[_pwmTimer]->duty_resolution = (ledc_timer_bit_t)resBit; // set duty resolution
// create PWM channel config structure
ledc_channel_config = new ledc_channel_config_t;
// seeding PWM channel config parameters
_ledc_channel_config->channel = (ledc_channel_t)_pwmChannel;
_ledc_channel_config->duty = 0;
_ledc_channel_config->hpoint = 0;
_ledc_channel_config->gpio_num = pwmPin;
_ledc_channel_config->speed_mode = LEDC_HIGH_SPEED_MODE;
_ledc_channel_config->timer_sel = (ledc_timer_t)_pwmTimer;
_ledc_channel_config->intr_type = LEDC_INTR_DISABLE;
// _ledc_channel_config->output_invert = 0; // don't work on Arduino ESP32 IDE
// start PWM signal on pwmPin.
ledc_channel_config(_ledc_channel_config);
// set ledc fade service on for ledc_set_duty_and_update/ledc_set_fade_time_and_start functions
ledc_fade_func_install(0);
...
// output duty to port
ledc_set_duty_and_update(LEDC_HIGH_SPEED_MODE, (ledc_channel_t)_pwmChannel, dutyToWrite, 0);Debug Message
Error returned by compilator while output_invert struct flag is provided
error: 'struct ledc_channel_config_t' has no member named 'output_invert'
_ledc_channel_config->output_invert = 0;
^~~~~~~~~~~~~
exit status 1
Other Steps to Reproduce
No response
I have checked existing issues, online documentation and the Troubleshooting Guide
- I confirm I have checked existing issues, online documentation and Troubleshooting guide.