Waveshare RP2040-Zero pinout: every pin, the NeoPixel and the bottom row

The Waveshare RP2040-Zero is the Raspberry Pi Pico’s RP2040 on a board 23.5 by 18 mm, with a USB-C socket, nine pins down each side and five along the bottom. Every pin is named by its GPIO, so the pin marked GP4 is GPIO 4 in code. This page lists all twenty-three pins in Waveshare’s order with what each one can do, the bus defaults, the PWM slices, the NeoPixel and why the board does not belong in a breadboard.

The circuit above is the board in Mokxi on its own, fading its NeoPixel on GP16 around the color wheel. There is no plain LED on the board, which is the first thing to know about it. The table is held to the same board model the simulator runs, and where Mokxi does less than the chip, the page says so.

The five bottom pins, GP13 to GP9, run across the board in one line. Pushed into a breadboard with the side rows straddling the channel, that line lies along the breadboard’s strips, so GP9 and GP10 land in the same strip and short together. Mokxi models this as the bench does: push the board in and the two pins are one net.

So keep the RP2040-Zero beside the breadboard and reach it with jumper wires, as the Blink starter does with an LED and a 220 ohm resistor on GP0. The two side rows alone carry I2C, SPI and all four analog inputs, so most projects never need the bottom row; Serial2’s RX on GP9 is the one bus pin down there.

The analog inputs are GP26 to GP29, which are A0 to A3, the RP2040’s four ADC inputs, all on the left side. analogRead returns ten bits against 3.3 V unless analogReadResolution asks for more. On a Pico, GP29 measures VSYS inside the board; here it is a pin of its own.

Every GPIO pin can do PWM, and GPIO n is on slice (n / 2) mod 8, channel A for an even pin and B for an odd one. Pins on one slice share a frequency, so GP0 and GP1 share slice 0, and GP10, GP11, GP26 and GP27 all sit on slice 5. Nine more GPIOs, GP17 to GP25, come out as solder pads on the back of the board. Mokxi does not model those pads.

Beside the USB-C socket are two buttons, BOOT and RESET, and the board carries 2 MB of flash, as a Pico does. To put a sketch on a real one, hold BOOT while you plug it in, or hold BOOT and tap RESET: the RP2040 then shows up as a drive called RPI-RP2, and the Arduino IDE, or a .uf2 dragged onto that drive, writes the flash. After the first upload the Arduino core usually resets the board into that mode by itself, so the buttons are only needed when a sketch has crashed the USB port.