Circuit Documentation

Summary

This document provides a detailed overview of a circuit that includes a Raspberry Pi Pico microcontroller, various sensors, a display, and other components. The circuit is designed to interface with multiple peripherals and perform specific tasks as defined by the embedded code.

Component List

1. Raspberry Pi Pico

   • Description: A low-cost, high-performance microcontroller board with flexible digital interfaces.
   • Pins: 43 pins including GPIO, power, and ground pins.

2. Bi-Directional Logic Level Converter

   • Description: A device used to safely step down 5V signals to 3.3V and step up 3.3V to 5V.
   • Pins: HV1, HV2, HV, GND, HV3, HV4, LV1, LV2, LV, LV3, LV4.

3. MQ-9 Breakout

   • Description: A gas sensor module that detects carbon monoxide and other gases.
   • Pins: VCC, GND, DO, AO.

4. Potentiometer

   • Description: A variable resistor used to adjust levels such as volume or signal strength.
   • Pins: GND, Output, VCC.

5. Mosfet

   • Description: A type of transistor used for switching and amplifying electronic signals.
   • Pins: Gate, Drain, Source.

6. Buzzer

   • Description: An audio signaling device.
   • Pins: POSITIVE, NEGATIVE.

7. Resistor (200 Ohms)

   • Description: A passive electrical component that limits current flow.
   • Pins: pin1, pin2.

8. Resistor (220 Ohms)

   • Description: A passive electrical component that limits current flow.
   • Pins: pin1, pin2.

9. Pushbutton START

   • Description: A simple pushbutton switch.
   • Pins: NC, NO.

10. 16x2 I2C LCD

    • Description: A 16x2 character LCD display with I2C interface.
    • Pins: GND, VCC, SDA, SCL.

Wiring Details

Raspberry Pi Pico

• pin 3: Connected to GND of Potentiometer, GND of Bi-Directional Logic Level Converter, pin1 of Resistor (200 Ohms), pin1 of Resistor (220 Ohms), and NO of Pushbutton START.
• pin 19: Connected to NO of Pushbutton START.
• pin 20: Connected to pin2 of Resistor (200 Ohms) and pin2 of Resistor (200 Ohms).
• pin 24: Connected to SDA of 16x2 I2C LCD.
• pin 25: Connected to SCL of 16x2 I2C LCD.
• pin 31: Connected to Output of Potentiometer.
• pin 34: Connected to LV1 of Bi-Directional Logic Level Converter.
• pin 36: Connected to VCC of Potentiometer and LV of Bi-Directional Logic Level Converter.
• pin 38: Connected to GND of 16x2 I2C LCD, GND of MQ-9 Breakout, GND of Bi-Directional Logic Level Converter, and Source of Mosfet.
• pin 40: Connected to VCC of 16x2 I2C LCD, VCC of MQ-9 Breakout, POSITIVE of Buzzer, and HV of Bi-Directional Logic Level Converter.

Bi-Directional Logic Level Converter

• GND: Connected to GND of Potentiometer, pin1 of Resistor (200 Ohms), pin1 of Resistor (220 Ohms), and NO of Pushbutton START.
• LV1: Connected to pin 34 of Raspberry Pi Pico.
• LV: Connected to VCC of Potentiometer and pin 36 of Raspberry Pi Pico.
• HV: Connected to VCC of 16x2 I2C LCD, VCC of MQ-9 Breakout, POSITIVE of Buzzer, and pin 40 of Raspberry Pi Pico.
• HV1: Connected to pin2 of Resistor (220 Ohms) and AO of MQ-9 Breakout.

MQ-9 Breakout

• GND: Connected to GND of 16x2 I2C LCD, GND of Bi-Directional Logic Level Converter, and Source of Mosfet.
• VCC: Connected to VCC of 16x2 I2C LCD, POSITIVE of Buzzer, and HV of Bi-Directional Logic Level Converter.
• AO: Connected to pin2 of Resistor (220 Ohms) and HV1 of Bi-Directional Logic Level Converter.

Potentiometer

• GND: Connected to GND of Bi-Directional Logic Level Converter, pin1 of Resistor (200 Ohms), pin1 of Resistor (220 Ohms), and NO of Pushbutton START.
• Output: Connected to pin 31 of Raspberry Pi Pico.
• VCC: Connected to LV of Bi-Directional Logic Level Converter and pin 36 of Raspberry Pi Pico.

Mosfet

• Gate: Connected to pin1 of Resistor (200 Ohms).
• Drain: Connected to NEGATIVE of Buzzer.
• Source: Connected to GND of 16x2 I2C LCD, GND of MQ-9 Breakout, GND of Bi-Directional Logic Level Converter, and pin 38 of Raspberry Pi Pico.

Buzzer

• POSITIVE: Connected to VCC of 16x2 I2C LCD, VCC of MQ-9 Breakout, HV of Bi-Directional Logic Level Converter, and pin 40 of Raspberry Pi Pico.
• NEGATIVE: Connected to Drain of Mosfet.

Resistor (200 Ohms)

• pin1: Connected to GND of Potentiometer, GND of Bi-Directional Logic Level Converter, pin1 of Resistor (220 Ohms), and NO of Pushbutton START.
• pin2: Connected to pin2 of Resistor (200 Ohms) and pin 20 of Raspberry Pi Pico.

Resistor (220 Ohms)

• pin1: Connected to GND of Potentiometer, GND of Bi-Directional Logic Level Converter, pin1 of Resistor (200 Ohms), and NO of Pushbutton START.
• pin2: Connected to AO of MQ-9 Breakout and HV1 of Bi-Directional Logic Level Converter.

Pushbutton START

• NO: Connected to GND of Potentiometer, GND of Bi-Directional Logic Level Converter, pin1 of Resistor (200 Ohms), pin1 of Resistor (220 Ohms), and pin 3 of Raspberry Pi Pico.
• NO: Connected to pin 19 of Raspberry Pi Pico.

16x2 I2C LCD

• GND: Connected to GND of MQ-9 Breakout, GND of Bi-Directional Logic Level Converter, and pin 38 of Raspberry Pi Pico.
• VCC: Connected to VCC of MQ-9 Breakout, POSITIVE of Buzzer, HV of Bi-Directional Logic Level Converter, and pin 40 of Raspberry Pi Pico.
• SDA: Connected to pin 24 of Raspberry Pi Pico.
• SCL: Connected to pin 25 of Raspberry Pi Pico.

Documented Code

sketch.ino

void setup() {
  // put your setup code here, to run once:

}

void loop() {
  // put your main code here, to run repeatedly:

}

documentation.txt