Circuit Documentation

Summary

The circuit in question appears to be designed for controlling heating pads via relay modules, with an Arduino UNO as the central microcontroller. The circuit includes a shift register (74HC595) for expanding the digital outputs of the Arduino, a relay module to switch higher voltage loads, a thermistor (NTC) for temperature sensing, and two heating pads. A 12v battery is used to power the heating pads, while the Arduino and other ICs are powered by lower voltages.

Component List

Arduino UNO

• Microcontroller board based on the ATmega328P
• Provides digital I/O pins, analog inputs, and various power outputs

12v Battery

• Power source for the heating pads
• Provides a voltage of 12 volts

74HC595 Shift Register

• 8-bit serial-in, parallel-out shift register
• Expands the number of digital outputs from the Arduino

Relay Module 2 Channel

• Module with two independent relay channels
• Allows for controlling high power devices like heating pads

NTC (Negative Temperature Coefficient) Thermistor

• A resistor whose resistance decreases with increasing temperature
• Used for temperature sensing in the circuit

SparkFun Heating Pad (x2)

• Flexible heating pads for generating heat
• Powered by the 12v battery through the relay module

Resistor

• A passive two-terminal electrical component
• Used in the circuit with a value of 10,000 Ohms

Wiring Details

Arduino UNO

• 5V pin connected to the NTC thermistor
• GND pin connected to a 10k Ohm resistor
• Digital pins D7, D6, D5, D3, and D2 connected to the relay module and 74HC595 shift register

12v Battery

• + terminal connected to the common (COM) pins of the relay module
• - terminal connected to the heating pads

74HC595 Shift Register

• MR (SRCLR) and VCC pins connected to the VCC of the relay module
• OE (Enable) and GND pins connected to the GND of the relay module
• DS (DATA), SH_CP (SRCLK), and ST_CP (RCLK) pins connected to Arduino digital pins D6, D5, and D3 respectively

Relay Module 2 Channel

• VCC and GND pins connected to the 74HC595 shift register
• IN1 and IN2 pins connected to Arduino digital pins D7 and D2
• NO1 and NO2 pins connected to the heating pads

NTC Thermistor

• One pin connected to the 5V pin of the Arduino
• The other pin connected to a 10k Ohm resistor

SparkFun Heating Pad

• Connected to the - terminal of the 12v battery and the normally open (NO) contacts of the relay module

Resistor

• One pin connected to the GND pin of the Arduino
• The other pin connected to the NTC thermistor

Documented Code

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

}

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

}

The provided code is a template with empty setup() and loop() functions, which are the standard structure for Arduino sketches. The setup() function is intended to contain initialization code that runs once when the microcontroller is powered on or reset. The loop() function is for code that runs continuously as long as the Arduino is powered.

Further implementation details would be required to provide a functional sketch that interacts with the hardware components as described in the wiring details. This would typically involve setting pin modes in the setup() function and controlling the pins in the loop() function to read sensors, drive the shift register, and activate the relays.