How to make ESP32 output 20MHZ's clock

[roctwo]

Hi!
How to make ESP32 output 20MHZ's clock? And can you provide code?

[kolban]

Do you mean you want a square wave output on a GPIO pin that has a frequency of 20MHz? If so, you can likely use the PWM functions.

[roctwo]

OK ,Thank you,sorry for my bad English.I will check it

[ppisljar]

seems pwm can only be used to generate 333k clock ... what about higher frequencies ?

[ESP_krzychb]

How to make ESP32 output 20MHZ's clock? And can you provide code?

Below is an example how to generate 20MHz square wave at 50% duty on GPIO18.

Code: [Select all] [Expand/Collapse]

1. #include "driver/ledc.h"
2.  
3. ledc_timer_config_t ledc_timer = {
4.     .speed_mode = LEDC_HIGH_SPEED_MODE,
5.     .timer_num  = LEDC_TIMER_0,
6.     .bit_num    = 2,
7.     .freq_hz    = 20000000
8. };
9.  
10. ledc_channel_config_t ledc_channel = {
11.     .channel    = LEDC_CHANNEL_0,
12.     .gpio_num   = 18,
13.     .speed_mode = LEDC_HIGH_SPEED_MODE,
14.     .timer_sel  = LEDC_TIMER_0,
15.     .duty       = 2
16. };
17.  
18. void app_main()
19. {
20.     ledc_timer_config(&ledc_timer);
21.     ledc_channel_config(&ledc_channel);
22.     while (1) {
23.         ;
24.     }
25. }

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The LED PWM Controller can generate up to 40MHz square wave.