This week we will use KiCad as an EDA tool for the design of a development board. The goal is to create a functional circuit that takes advantage of the components available in inventory, the board should be able to interface with a microcontroller.
| Software | Función |
|---|---|
| KiCad | KiCad is an EDA tool used to design electronic circuits and create printed circuit boards (PCBs). |
Temperature Meter with Thermistor and Xiao RP2040
Create a New Project
Click on File → New Project and choose a name and location.
Several files will be generated:
- Schematic (.sch) → For the electrical diagram
- PCB (.kicad_pcb) → For the board design
Select a Component
Click on the "Add Component" icon or press the "A" key on your keyboard.
A window will appear where you can search for the component you need. Type the name or select from the available libraries.
Once selected, click on the schematic where you want to place it.
Search and select the necessary components:
- Xiao RP2040
- LED
- Resistors (R)
- Capacitors (C)
- NTC Thermistor
It includes an LED with a 330 Ω resistor for current limiting, an NTC thermistor with a 10 kΩ pull-up resistor to form a voltage divider and enable temperature measurement, and a 0.1 µF capacitor for decoupling and filtering of the 3.3V supply. These values guarantee a safe and stable operation of the circuit, facilitating its integration in a compact and efficient PCB.
Power Supply Components
3.3V (PWR_3V3)
Voltage SourcePrimary power supply delivering stable 3.3V DC for circuit operation
Ground (PWR_GND)
ReferenceCommon return path completing electrical circuit configuration
Capacitor (C1)
Filters high-frequency noise and stabilizes voltage fluctuations
Resistor (R2)
Current limiter for component protection (10 kΩ ±5%)
NTC Thermistor (TH1)
Thermal SensorNegative temperature coefficient device (R25°C = 10 kΩ)
LED (D1)
Visual status indicator with integrated current protection
Resistor (R1)
LED current regulator (330 Ω ±1%)
Microcontroller Unit
Central ProcessorProgrammable IC managing sensor inputs and output controls through GPIO interfaces
Technical Specifications: Operating Voltage 3.3V ±5% | Thermal Range: -40°C to 85°C | Maximum Current Draw: 150mA
Access the ERC checker
In the toolbar, click on the ERC icon (it is like a leaf with a magnifying glass) or select “Tools > Electrical Rule Checker”.
Run the check:
Click on the “Run ERC” button. This will generate a list of errors and warnings in a results window.
Analyze the results: Each error or warning will have a message explaining the problem.
Click on the errors to have KiCad take you to the place in the schematic where it occurs.
