The Raspberry Pi Pico 2 W upgrades the original wireless footprint with the dual-core RP2350 chip (Arm Cortex-M33 / RISC-V) and the Infineon CYW43439 Wi-Fi 4/Bluetooth 5.2 module. While the physical board dimensions and header spacing remain identical to the Pico 1 W, the internal routing, drive strengths, and security features of the RP2350 demand a precise understanding of the pinout before you wire up your first sensor or power rail.
The Complete Raspberry Pi Pico 2 W Pinout Reference
The table below maps the physical header pins to the RP2350 GPIOs, their primary functions, and critical electrical limits. This is your bench reference for wiring. Note that the RP2350 package actually contains 48 GPIOs, but the Pico 2 W board only breaks out 26 multi-function pins (GP0-GP22 and GP26-GP28) to maintain backward compatibility with Pico 1 add-on boards.
| Physical Pin | GPIO / Net | Primary Function | Alternate / Bus Functions | Voltage & Current Limits |
|---|---|---|---|---|
| 1, 2 | GP0, GP1 | Digital I/O | UART0 (TX/RX), I2C0, SPI0 | 3.3V logic, 4mA default drive (up to 12mA configurable) |
| 4, 5 | GP2, GP3 | Digital I/O | I2C1, SPI0, PWM | 3.3V logic, 4mA default drive |
| 6, 7 | GP4, GP5 | Digital I/O | UART1, I2C0, SPI0 | 3.3V logic, 4mA default drive |
| 9-15 | GP6-GP15 | Digital I/O | PWM, PIO, I2C/SPI/UART mapped | 3.3V logic, 4mA default drive |
| 16-22 | GP16-GP22 | Digital I/O | SPI0 (RX/TX/SCK/CS), PIO | 3.3V logic, 4mA default drive |
| 23-26 | GND | Ground Reference | Common ground for logic and power | 0V reference |
| 27 | GP26 / ADC0 | Digital I/O / Analog In | I2C1 SDA, SPI1 SCK | 3.3V max analog input (12-bit ADC) |
| 28 | GP27 / ADC1 | Digital I/O / Analog In | I2C1 SCL, SPI1 TX | 3.3V max analog input (12-bit ADC) |
| 29 | GP28 / ADC2 | Digital I/O / Analog In | SPI1 RX, PWM | 3.3V max analog input (12-bit ADC) |
| 30 | ADC_VREF | ADC Reference Voltage | Internally tied to 3.3V via filter | 3.3V nominal |
| 31 | GP22 / ADC3 | Digital I/O | Often used for internal temp sensor | 3.3V logic |
| 36 | 3V3_OUT | 3.3V Power Output | Output from the onboard SMPS regulator | 3.3V, max ~300mA total board limit |
| 37 | 3V3_EN | Regulator Enable | Pull low to disable the 3.3V SMPS | 3.3V logic level |
| 39 | VSYS | System Power Input | Main power input (1.8V to 5.5V) | Max 5.5V absolute |
| 40 | VBUS | USB 5V Power | Tied to USB VBUS through a diode | 5V nominal (4.75V - 5.25V) |
Rows and Pins People Get Wrong (and Internal Wireless Mapping)
When debugging a Pico 2 W that isn't behaving, the issue almost always traces back to a misinterpretation of the pinout table. Here are the specific rows and internal mappings that trip up even experienced embedded engineers.
The "Missing" GPIOs: CYW43439 Wireless Routing
If you count the physical pins and compare them to the RP2350 datasheet, you'll notice GP23, GP24, GP25, and GP29 are missing from the user-accessible header. Do not attempt to use these in your code. They are internally hardwired to the Infineon CYW43439 Wi-Fi/Bluetooth module via an SDIO interface:
- GP23: WL_HOST_WAKE (Wireless chip interrupt/wake)
- GP24: WL_SDIO_CMD (SDIO Command line)
- GP25: WL_SDIO_CLK (SDIO Clock)
- GP29: WL_SDIO_D0 (SDIO Data 0, also used for SPI chip select fallback)
Furthermore, the onboard user LED is not on a standard GPIO; it is routed through the wireless chip's internal GPIO (WL_GPIO0). To blink the LED in MicroPython or C, you must use the specific `cyw43` architecture libraries, not a standard digital write command.
The RP2350 GPIOs are strictly 3.3V tolerant. Feeding a 5V sensor output directly into GP0-GP28 will forward-bias the internal ESD protection diodes, causing excessive let-through current that will permanently brick the silicon. Always use a logic level converter or a voltage divider for 5V I2C/SPI devices.
ADC Pin Behavior (GP26-GP28)
When using GP26, GP27, or GP28 as analog inputs (ADC0-ADC2), remember that the RP2350 ADC has an input impedance of roughly 400 ohms when sampling. If your sensor has a high output impedance (like a simple resistive voltage divider using 100kΩ resistors), the ADC will pull the voltage down during the sample-and-hold phase, resulting in wildly inaccurate readings. Keep your source impedance under 5kΩ, or buffer the signal with an op-amp.
Standard Variants: Official Silkscreen vs. IEC Logic Symbols vs. Clones
While NEC and IEC color codes govern mains wiring, embedded systems have their own regional and organizational standard variants that cause confusion when reading third-party schematics or using European educational kits.
| Standard / Variant | SPI Naming Convention | I2C Default Bus | Where You Will See It |
|---|---|---|---|
| Raspberry Pi Official (Global) | SPI0 RX / TX / SCK / CS | I2C1 (GP6/GP7) | Official Pico 2 W silkscreen and datasheets |
| IEC 60617 / IEEE Legacy | MISO / MOSI / SCLK / SS | I2C0 or I2C1 | European university lab manuals, older sensor breakout boards |
| Modern IEC / OSHWA | CIPO / COPI / SCK / CS | SDA / SCL | Newer open-source hardware schematics (2024+) |
| Third-Party Clones (e.g., Waveshare) | Varies, often adds QSPI pins | Often breaks out I2C0 | RP2350 clone boards with expanded 48-GPIO footprints |
Which standard applies to you? If you are wiring bare sensors, follow the physical Raspberry Pi silkscreen (SPI0 RX/TX). If you are integrating a Pico 2 W into a larger industrial control panel designed by a European engineering firm, their schematics will likely use IEC 60617 logic symbols (CIPO/COPI). Map CIPO to the Pi's SPI RX, and COPI to the Pi's SPI TX. Never assume MISO/MOSI without verifying the controller's role (master vs. peripheral) in the SPI bus.
Safe Interpretation When Markings are Faded or Missing
On the bench, you'll eventually encounter a Pico 2 W with rubbed-off silkscreen, flux residue obscuring the text, or an unmarked white-label RP2350 clone board. Guessing pin assignments will destroy your board. Use this multimeter decision path to safely identify the power and ground rails before applying voltage.
- Identify GND (Pins 3, 8, 13, 18, 23, 38): Set your multimeter to continuity or diode mode. Probe the metal shield of the micro-USB/USB-C connector. The pin that shows a dead short (less than 0.5 ohms or a 0.000V diode drop) to the USB shield is your ground rail. Map the adjacent pins from there.
- Identify VBUS (Pin 40): With the board unpowered, set the meter to diode mode. Place the red probe on the suspected VBUS pin and the black probe on GND. You should read a forward voltage drop of roughly 0.3V to 0.5V (due to the Schottky diode in the power path). Reversing the probes should read "OL" (open loop).
- Identify VSYS (Pin 39): VSYS will show a direct short to VBUS if the USB cable is unplugged and the board is unpowered, but it sits on the input side of the power path diode. If you measure 0.000V drop in both directions to VBUS, you are likely on VSYS or a raw 5V trace.
- Identify 3V3_OUT (Pin 36): Do not rely on continuity for the 3.3V rail. The onboard SMPS (switch-mode power supply) inductor and internal MOSFETs will give erratic diode readings. The only safe way to verify Pin 36 is to apply a known-good 5V to VBUS and measure the output with the DC voltage setting. It must read between 3.25V and 3.35V.
For comprehensive electrical characteristics, including the exact RP2350 timing diagrams and CYW43439 SDIO routing, always cross-reference your physical board against the official Raspberry Pi Pico 2 Datasheet and the RP2350 Silicon Documentation. Local code and specific project requirements may dictate additional isolation or level-shifting beyond the chip's native capabilities.
