Circuit Documentation

Summary

This circuit is designed to control a welding pen using an ESP32 microcontroller. It includes a rotary encoder for user input, a TFT display for visual feedback, LEDs for status indication, a piezo buzzer for audio feedback, and a solid-state relay (SSR) for controlling high-power devices. The circuit also includes a toggle switch and pushbuttons for additional user controls.

Component List

1. Esp32 on Baseboard

   • Description: Microcontroller used for controlling the circuit.
   • Pins: GPIO23, GPIO22, GPIO1/TX, GPIO3/RX, GPIO21, GPIO19, GPIO18, GPIO5, GPIO17, GPIO16, GPIO4, GPIO0, GPIO2, GPIO15, SD1, SD0, CLK, V, G, GPIO36, GPIO39, GPIO34, GPIO35, GPIO32, GPIO33, GPIO25, GPIO26, GPIO27, GPIO14, GPIO12, GPIO13, SD2, SD3, GND, 5V, 3V, TX, RX, VCC, D22, D21

2. Rotary Encoder

   • Description: Used for user input to adjust settings.
   • Pins: clk, dt, sw, gnd, +

3. Round TFT Display

   • Description: Provides visual feedback to the user.
   • Pins: RST, CS, DC, SDA, SCL, GND, VCC

4. Pushbutton

   • Description: Used for user input.
   • Pins: Pin 3 (out), Pin 4 (out), Pin 1 (in), Pin 2 (in)

5. 12v Battery

   • Description: Power source for the circuit.
   • Pins: -, +

6. MOSFET Bank of 40xIRF540N

   • Description: Used for switching high-power loads.
   • Pins: Drain A, Drain B, Source A1, Source A2, Gate A1, Gate A2, Gate B1, Gate B2, Source B1, Source B2

7. 18650 Battery Welding Pen

   • Description: The welding pen controlled by the circuit.
   • Pins: + INPUT, - INPUT

8. SSR-40A

   • Description: Solid-state relay for controlling high-power devices.
   • Pins: -, +, Lin, Lout

9. RGB LED

   • Description: Provides visual status indication.
   • Pins: B, G, R, GND

10. Piezo Buzzer

    • Description: Provides audio feedback.
    • Pins: pin 1, pin 2

11. Toggle Switch SPST

    • Description: Used for toggling the ready state.
    • Pins: L1, COM

12. LED: Two Pin (green)

    • Description: Provides visual status indication.
    • Pins: cathode, anode

13. LED: Two Pin (red)

    • Description: Provides visual status indication.
    • Pins: cathode, anode

Wiring Details

Esp32 on Baseboard

• GPIO23: Connected to SDA pin of the Round TFT Display
• GPIO18: Connected to SCL pin of the Round TFT Display
• GPIO5: Connected to CS pin of the Round TFT Display
• GPIO17: Connected to anode pin of the LED: Two Pin (red)
• GPIO16: Connected to anode pin of the LED: Two Pin (green)
• GPIO4: Connected to L1 pin of the Toggle Switch SPST
• GPIO2: Connected to DC pin of the Round TFT Display
• GPIO15: Connected to RST pin of the Round TFT Display
• G: Connected to cathode pin of the LED: Two Pin (red), cathode pin of the LED: Two Pin (green), COM pin of the Toggle Switch SPST, Pin 4 (out) of the Pushbutton, - pin of the SSR-40A
• GPIO35: Connected to pin 1 of the Piezo Buzzer
• GPIO32: Connected to clk pin of the Rotary Encoder
• GPIO33: Connected to dt pin of the Rotary Encoder
• GPIO25: Connected to sw pin of the Rotary Encoder
• GPIO26: Connected to B pin of the RGB LED
• GPIO27: Connected to G pin of the RGB LED
• GPIO14: Connected to R pin of the RGB LED
• GPIO12: Connected to Pin 4 (out) of the Pushbutton
• GPIO13: Connected to + pin of the SSR-40A
• GND: Connected to gnd pin of the Rotary Encoder, pin 2 of the Piezo Buzzer, GND pin of the RGB LED, GND pin of the Round TFT Display
• 5V: Connected to + pin of the Rotary Encoder
• VCC: Connected to VCC pin of the Round TFT Display

Rotary Encoder

• clk: Connected to GPIO32 pin of the Esp32 on Baseboard
• dt: Connected to GPIO33 pin of the Esp32 on Baseboard
• sw: Connected to GPIO25 pin of the Esp32 on Baseboard
• gnd: Connected to GND pin of the Esp32 on Baseboard
• +: Connected to 5V pin of the Esp32 on Baseboard

Round TFT Display

• SDA: Connected to GPIO23 pin of the Esp32 on Baseboard
• SCL: Connected to GPIO18 pin of the Esp32 on Baseboard
• CS: Connected to GPIO5 pin of the Esp32 on Baseboard
• DC: Connected to GPIO2 pin of the Esp32 on Baseboard
• RST: Connected to GPIO15 pin of the Esp32 on Baseboard
• GND: Connected to GND pin of the Esp32 on Baseboard
• VCC: Connected to VCC pin of the Esp32 on Baseboard

Pushbutton

• Pin 2 (in): Connected to GPIO12 pin of the Esp32 on Baseboard
• Pin 4 (out): Connected to G pin of the Esp32 on Baseboard

12v Battery

• -: Connected to Lin pin of the SSR-40A
• +: Connected to + INPUT pin of the 18650 Battery Welding Pen

MOSFET Bank of 40xIRF540N

• Source A1: Connected to Source A2, Source B1, Source B2
• Drain A: Connected to Drain B, - INPUT pin of the 18650 Battery Welding Pen
• Gate A1: Connected to Gate A2, Gate B1, Gate B2

18650 Battery Welding Pen

• + INPUT: Connected to + pin of the 12v Battery
• - INPUT: Connected to Drain A pin of the MOSFET Bank of 40xIRF540N

SSR-40A

• -: Connected to G pin of the Esp32 on Baseboard
• +: Connected to GPIO13 pin of the Esp32 on Baseboard
• Lin: Connected to - pin of the 12v Battery
• Lout: Connected to Gate A1 pin of the MOSFET Bank of 40xIRF540N

RGB LED

• B: Connected to GPIO26 pin of the Esp32 on Baseboard
• G: Connected to GPIO27 pin of the Esp32 on Baseboard
• R: Connected to GPIO14 pin of the Esp32 on Baseboard
• GND: Connected to GND pin of the Esp32 on Baseboard

Piezo Buzzer

• pin 1: Connected to GPIO35 pin of the Esp32 on Baseboard
• pin 2: Connected to GND pin of the Esp32 on Baseboard

Toggle Switch SPST

• L1: Connected to GPIO4 pin of the Esp32 on Baseboard
• COM: Connected to G pin of the Esp32 on Baseboard

LED: Two Pin (green)

• anode: Connected to GPIO16 pin of the Esp32 on Baseboard
• cathode: Connected to G pin of the Esp32 on Baseboard

LED: Two Pin (red)

• anode: Connected to GPIO17 pin of the Esp32 on Baseboard
• cathode: Connected to G pin of the Esp32 on Baseboard

Code Documentation

#include <TFT_eSPI.h> // TFT display library
#include <Preferences.h> // Persistent storage library
#include <ESP32Encoder.h> // Rotary encoder library
#include <Ticker.h> // Timer library

// Pin definitions
#define RST_PIN 15
#define CS_PIN 5
#define DC_PIN 2
#define SDA_PIN 23
#define SCL_PIN 18
#define ENCODER_CLK_PIN 32
#define ENCODER_DT_PIN 33
#define ENCODER_SW_PIN 25
#define ACTIVATE_PIN 12
#define RESET_PIN 0 // EN