digital_potentiometer.h

#pragma once

#include "esphome.h"

//define differents pins of X9CXXX board
#define CSPIN 16
#define INCPIN 17
#define UDPIN 18

class DigitalPotentiometer : public Component
{
public:
  bool enable = false; //sending data to X9CXXX or not
  int current_step = 0; //current value between 0 and 100
  int new_step = 0; //value to be setted between 0 and 100

  DigitalPotentiometer(esphome::template_::TemplateSwitch *&_enable, esphome::template_::TemplateNumber *&_step)
  {
    _enable->add_on_state_callback([this](bool newState)
                                   { enable = newState; });
    _step->add_on_state_callback([this](int newStep)
                                      { new_step = newStep; });
  }


   void setup() override
   {
     pinMode(CSPIN,OUTPUT);
     pinMode(INCPIN,OUTPUT);
     pinMode(UDPIN,OUTPUT);
     reset();
   }

   void loop() override //only active when send_data_x9c qwitch is on
   {
     if (enable)
     {
       go_to_step();
     }
   }

   void reset() //reset X9CXXX to a known value
   {
 		digitalWrite(CSPIN, LOW);
 		digitalWrite(UDPIN, LOW);
 		for (uint8_t i = 0; i < 100; i++)
 		{
 			digitalWrite(INCPIN, LOW);
 			delayMicroseconds(100);
 			digitalWrite(INCPIN, HIGH);
 		  delayMicroseconds(100);
 		}
    digitalWrite(UDPIN, HIGH);
    digitalWrite(CSPIN, HIGH);
 		current_step = 0;
 	}

   void go_to_step()
   {
     digitalWrite(CSPIN, LOW);
     while (current_step != new_step)
     {
       if (current_step > new_step)
       {
         digitalWrite(UDPIN, LOW);
         digitalWrite(INCPIN, LOW);
         delayMicroseconds(100);
         digitalWrite(INCPIN, HIGH);
         delayMicroseconds(100);
         if (current_step > 0) current_step--;
       }
       else
       {
         digitalWrite(UDPIN, HIGH);
         digitalWrite(INCPIN, LOW);
         delayMicroseconds(100);
         digitalWrite(INCPIN, HIGH);
         delayMicroseconds(100);
         if (current_step < 100) current_step++;
       }
     }
     digitalWrite(CSPIN, HIGH);
   }

}; //class

esp_X9C.yaml

esphome:
  # ... [Other options]...
  includes:
    - custom_componenent/digital_potentiometer.h
    
#wifi...
#... your personnal code... 

number: #value to be setted on X9CXXX between 0 and 100
  - platform: template
    name: "X9C Position"
    id: x9c_position
    optimistic: true
    min_value: 1
    max_value: 100
    step: 1

switch: #//sending data to X9CXXX or not
  - platform: template
    name: "Send Data to X9C"
    id: send_data_x9c
    optimistic: true

custom_component:
- lambda: |-
    auto myComponent = new DigitalPotentiometer(id(send_data_x9c), id(x9c_position));
    return {myComponent};

https://github.com/esphome/feature-requests/issues/1270 for more informations