RP2040-Zero Getting Started Guide: Pinout, Arduino IDE Setup, and RGB LED Blink

One important thing to remember is that RP2040 GPIO pins are 3.3V logic pins. Do not connect a 5V signal directly to a GPIO pin. If you are working with 5V modules, use a level shifter or check if the module’s output is already 3.3V-safe.

Powering the RP2040-Zero

The easiest way to power the RP2040-Zero is through the USB-C connector. For most beginner projects, this is what I recommend.

You can also power the board through its power pins, but be careful. Waveshare notes that the board does not include battery protection, and if you power it from a battery you must handle charging, over-discharge protection, and backflow protection yourself.

For a first test, use USB-C. It removes many possible mistakes.

Setting Up Arduino IDE for RP2040-Zero

The RP2040-Zero can be programmed in different ways, including MicroPython, C/C++, and Arduino IDE. For this guide, we will use the Arduino IDE because it is usually the fastest way to test the board.

The Arduino support we will use is the Arduino-Pico core by Earle Philhower. Its official installation instructions say to add the RP2040 package URL in Arduino IDE Preferences, then install the board package from Boards Manager.

Step 1: Install Arduino IDE

Download and install the latest Arduino IDE from the Arduino website.

Step 2: Add the RP2040 Board Manager URL

Open Arduino IDE, then go to:

File > Preferences

In Additional Boards Manager URLs, add this URL:

https://github.com/earlephilhower/arduino-pico/releases/download/global/package_rp2040_index.json

If you already have another URL there, such as the ESP32 board URL, separate the URLs with a comma.

Step 3: Install the RP2040 Board Package

Go to:

Tools > Board > Boards Manager

Search for:

pico

Install:

Raspberry Pi Pico/RP2040 by Earle F. Philhower, III

Step 4: Select the Board

After installation, go to:

Tools > Board > Raspberry Pi RP2040 Boards

Select the RP2040-Zero/Waveshare RP2040-Zero option if it appears in your installed version. If your Arduino-Pico version does not show a specific RP2040-Zero option, you can use a generic RP2040 or Raspberry Pi Pico selection for simple tests, but the dedicated board entry is preferred when available.

Entering Boot Mode

For the first upload, you may need to put the board into bootloader mode manually.

There are two common ways to do it.

If the board is unplugged:

1. 1. Hold the BOOT button.
   2. Plug the USB-C cable into your computer.
   3. Release the BOOT button.
   4. A drive named something like RPI-RP2 should appear.

If the board is already plugged in:

1. 1. Press and hold RESET.
   2. Press and hold BOOT.
   3. Release RESET first.
   4. Release BOOT.
   5. The board should enter flashing mode.

Waveshare’s FAQ gives the same reset-and-boot sequence for flashing firmware.

First Arduino Program: Blink the Onboard RGB LED

On many Arduino boards, the first test is usually the standard Blink sketch. The RP2040-Zero is a little different because its onboard LED is not a normal LED connected directly to a GPIO pin.

The onboard LED is a WS2812B RGB LED, so it needs a NeoPixel-style signal. According to the RP2040-Zero schematic, the RGB LED data pin is connected to GPIO16.

Before uploading the code, install the Adafruit NeoPixel library:

Sketch > Include Library > Manage Libraries

Search for:

Adafruit NeoPixel

Install it, then upload this sketch:

#include <Adafruit_NeoPixel.h>

#define RGB_LED_PIN 16
#define NUM_LEDS 1

Adafruit_NeoPixel pixel(NUM_LEDS, RGB_LED_PIN, NEO_GRB + NEO_KHZ800);

void setup() {
  pixel.begin();
  pixel.setBrightness(30);  // Keep it low so it is not too bright
  pixel.clear();
  pixel.show();
}

void loop() {
  // Red
  pixel.setPixelColor(0, pixel.Color(255, 0, 0));
  pixel.show();
  delay(500);

  // Green
  pixel.setPixelColor(0, pixel.Color(0, 255, 0));
  pixel.show();
  delay(500);

  // Blue
  pixel.setPixelColor(0, pixel.Color(0, 0, 255));
  pixel.show();
  delay(500);

  // Off
  pixel.clear();
  pixel.show();
  delay(500);
}

After uploading, the onboard RGB LED should cycle through red, green, blue, then turn off.

If you uploaded the ordinary Arduino Blink example and nothing happened, the board is probably fine. The issue is just that the onboard LED is not a simple LED. You need the WS2812/NeoPixel code above.

Testing a Normal GPIO Pin

After testing the onboard RGB LED, it is also a good idea to test a normal GPIO pin with an external LED. This confirms that the board pins work as expected.

Connect:

#define LED_PIN 0

void setup() {
  pinMode(LED_PIN, OUTPUT);
}

void loop() {
  digitalWrite(LED_PIN, HIGH);
  delay(500);

  digitalWrite(LED_PIN, LOW);
  delay(500);
}

#define POT_PIN 26

void setup() {
  Serial.begin(115200);
}

void loop() {
  int value = analogRead(POT_PIN);

  Serial.print("ADC value: ");
  Serial.println(value);

  delay(300);
}