The Raspberry Pi Pico 2 W retains the familiar 40-pin DIP footprint of its predecessor but swaps the silicon for the dual-core RP2350 (Arm Cortex-M33 / Hazard3 RISC-V) and an Infineon CYW43439 Wi-Fi/Bluetooth module. While the physical board layout is identical to the original Pico W, the internal multiplexing, power delivery (now a switched-mode supply), and ADC performance have changed. Below is the direct, no-fluff reference you need to wire your sensors, debug your I2C buses, and avoid frying your new board.
The Complete Pico 2W Pinout Reference Table
The Pico 2 W exposes 26 general-purpose GPIOs (GP0–GP22, GP26–GP28) to the physical headers. Pins GP23, GP24, GP25, and GP29 are consumed internally by the wireless chip and system monitoring. Read the table from the bottom-left corner (Pin 1) up the left side, then down the right side, and finally across the bottom edge.
| Phys Pin | GPIO / Label | Primary / Mux Functions | RP2350 Specific Notes |
|---|---|---|---|
| 1 | GP0 | UART0 TX, SPI0 RX, I2C0 SDA | 5V-tolerant input (verify datasheet) |
| 2 | GP1 | UART0 RX, SPI0 CSn, I2C0 SCL | 5V-tolerant input |
| 3 | GND | Ground | Common return path |
| 4 | GP2 | UART0 CTS, SPI0 SCK, I2C1 SDA | 5V-tolerant input |
| 5 | GP3 | UART0 RTS, SPI0 TX, I2C1 SCL | 5V-tolerant input |
| 6 | GP4 | UART1 TX, SPI0 RX, I2C0 SDA | Default I2C0 SDA in many SDKs |
| 7 | GP5 | UART1 RX, SPI0 CSn, I2C0 SCL | Default I2C0 SCL in many SDKs |
| 8 | GND | Ground | Common return path |
| 9 | GP6 | UART1 CTS, SPI0 SCK, I2C1 SDA | Standard GPIO |
| 10 | GP7 | UART1 RTS, SPI0 TX, I2C1 SCL | Standard GPIO |
| 11 | GP8 | UART1 TX, SPI1 RX, I2C0 SDA | Standard GPIO |
| 12 | GP9 | UART1 RX, SPI1 CSn, I2C0 SCL | Standard GPIO |
| 13 | GND | Ground | Common return path |
| 14 | GP10 | UART1 CTS, SPI1 SCK, I2C1 SDA | Standard GPIO |
| 15 | GP11 | UART1 RTS, SPI1 TX, I2C1 SCL | Standard GPIO |
| 16 | GP12 | UART0 TX, SPI1 RX, I2C0 SDA | Standard GPIO |
| 17 | GP13 | UART0 RX, SPI1 CSn, I2C0 SCL | Standard GPIO |
| 18 | GND | Ground | Common return path |
| 19 | GP14 | UART0 CTS, SPI1 SCK, I2C1 SDA | Standard GPIO |
| 20 | GP15 | UART0 RTS, SPI1 TX, I2C1 SCL | Standard GPIO |
| 21 | GP16 | UART0 TX, SPI0 RX, I2C0 SDA | Standard GPIO |
| 22 | GP17 | UART0 RX, SPI0 CSn, I2C0 SCL | Standard GPIO |
| 23 | GND | Ground | Common return path |
| 24 | GP18 | UART0 CTS, SPI0 SCK, I2C1 SDA | Standard GPIO |
| 25 | GP19 | UART0 RTS, SPI0 TX, I2C1 SCL | Standard GPIO |
| 26 | GP20 | UART1 TX, SPI0 RX, I2C0 SDA | Standard GPIO |
| 27 | GP21 | UART1 RX, SPI0 CSn, I2C0 SCL | Standard GPIO |
| 28 | GND | Ground | Common return path |
| 29 | GP22 | UART1 CTS, SPI0 SCK, I2C1 SDA | Standard GPIO |
| 30 | RUN | Reset / Enable | Pull low to reset RP2350 |
| 31 | GP26 (ADC0) | UART1 RTS, SPI1 TX, I2C1 SCL | 12-bit ADC, 3.3V max limit |
| 32 | GP27 (ADC1) | Standard GPIO | 12-bit ADC, 3.3V max limit |
| 33 | AGND | Analog Ground | Use for precision ADC refs |
| 34 | GP28 (ADC2) | Standard GPIO | 12-bit ADC, 3.3V max limit |
| 35 | ADC_VREF | ADC Voltage Reference | Nominally 3.0V (filtered 3V3) |
| 36 | 3V3 (OUT) | 3.3V Power Output | Max ~300mA draw (SMPS regulated) |
| 37 | 3V3_EN | 3.3V SMPS Enable | Pull low to disable 3.3V rail |
| 38 | GND | Ground | Common return path |
| 39 | VSYS | System Input Voltage | Accepts 1.8V to 5.5V input |
| 40 | VBUS | USB VBUS Input | Connected directly to USB 5V |
Rows People Get Wrong (and How to Avoid Bricking Your Board)
When working with the pico 2w pinout, three specific areas consistently cause hardware failures or erratic sensor readings. Pay close attention to these edge cases.
Pin 40 (VBUS) is tied directly to the USB 5V line. Pin 39 (VSYS) is the input to the onboard SMPS. If you are powering the Pico 2W via a battery or external supply through VSYS, do not connect VBUS to your external 5V rail. If both are fed 5V simultaneously from different sources (e.g., USB and a bench supply), you will create a ground loop or backfeed the USB host, potentially destroying your PC's USB port. Use a Schottky diode if you must OR them together.
The ADC Voltage Limit (GP26-GP28): The RP2350 features a vastly improved 12-bit ADC compared to the RP2040, but the absolute maximum voltage on GP26, GP27, and GP28 remains 3.3V. Feeding a 5V analog sensor directly into these pins will degrade the internal ESD protection diodes over time, leading to "ghost" voltage readings even when the pin is grounded. Always use a voltage divider or an op-amp buffer for 5V analog signals.
The "Missing" Wireless Pins (GP23-GP25): If you are porting code from a standard Pico 2 (non-wireless), you will notice GP23, GP24, and GP25 are missing from the physical header. On the Pico 2 W, these are hardwired internally to the Infineon CYW43439 chip (WL_ON, WL_DATA, WL_CLK). Attempting to redefine these in your code for external peripherals will cause the Wi-Fi/Bluetooth stack to crash or fail to initialize.
Wiring Color Codes: IEC vs. NEC vs. Maker Standards
Microcontrollers don't have "regional" pinouts, but the wiring you connect to them is governed by different standards depending on your background. Misinterpreting a wire color from an industrial sensor vs. a hobbyist breakout board is a common source of shorts. Here is how to safely interpret the colors.
| Function | IEC 60446 (EU / Industrial) | US NEC (Mains / Legacy DC) | Maker Standard (Adafruit / SparkFun) |
|---|---|---|---|
| Power / VCC (3V3 or 5V) | Brown | Black (Hot) / Red (DC) | Red |
| Ground / GND | Blue | White (Neutral) / Black (DC GND) | Black |
| Earth / Shield | Green-Yellow | Green / Bare Copper | N/A (Rare on logic boards) |
| I2C SDA / Data | Varies by OEM | Varies by OEM | Blue |
| I2C SCL / Clock | Varies by OEM | Varies by OEM | Yellow |
Safe Interpretation When Markings are Faded or Missing: Never trust the color of cheap, mass-produced DuPont jumper wires—manufacturers frequently swap colors based on whatever spool is cheapest that week. If you inherit a harness with faded or non-standard colors, use a digital multimeter in continuity mode. Probe the suspected GND wire against the metal shield of the Pico's USB-C port (which is tied to ground). If it beeps, you have your ground reference. From there, trace the power rail back to the source before applying voltage.
Pico 2W Pinout FAQ
Is the Pico 2W pinout identical to the original Pico W?
Physically, yes. The 40-pin DIP footprint, mounting holes, and external GPIO assignments (GP0-GP22, GP26-GP28) are identical, meaning your existing PCBs and breadboard layouts will fit perfectly. Electrically, there are differences: the Pico 2W uses a switched-mode power supply (SMPS) instead of an LDO, meaning the 3V3 rail runs much cooler under heavy Wi-Fi load. Additionally, the RP2350 chip introduces a security-focused boot architecture and a vastly improved 12-bit ADC, but your basic machine.Pin MicroPython or C SDK code will map 1:1.
Can I use 5V logic on the Pico 2W GPIO pins?
The RP2350 datasheet notes that certain GPIO pins feature 5V-tolerant inputs, but this is highly dependent on the specific pad configuration and power state. As a strict bench rule: treat all Pico 2W GPIOs as 3.3V logic. If you need to interface with a 5V sensor (like an HC-SR04 ultrasonic module or a 5V Arduino), use a bidirectional logic level converter (like the BSS138 MOSFET-based modules) or a simple resistor voltage divider for the RX lines. Do not rely on the internal 5V tolerance for production designs.
How do I identify Pin 1 if the silicone boot and board markings are missing?
If you've stripped the board of its silicone cover and the white silkscreen text is scratched off, you can still reliably identify Pin 1 (GP0). Flip the board over. Look at the copper pads on the bottom-left corner (assuming the USB port is pointing "up" away from you). Pin 1 is the only pad with a square copper shape; all other pads are circular or oval. Alternatively, look at the top side of the black RP2350 chip itself—there is a tiny laser-etched dimple or dot in one corner indicating Pin 1 of the silicon, which correlates to the board's GP0 orientation. Always verify with a multimeter against the USB shield ground before applying power.
