The Raspberry Pi Pico 2 W upgrades the original wireless board with the dual-core RP2350 (featuring selectable Arm Cortex-M33 or RISC-V cores) and an Infineon CYW43439 Wi-Fi 4 / Bluetooth 5.2 module. Because the physical footprint and Micro-USB connector remain identical to the Pico 1 W, assuming the pinout behaviors are exactly the same is a common mistake. Internal routing, ADC performance, and power delivery on the RP2350 have distinct characteristics. Here is the exact reference you need at the bench.
The Complete Raspberry Pi Pico 2 W Pinout Table
The Pico 2 W features 26 multi-function GPIO pins, 3 dedicated ADC channels, and specialized power routing. Below is the full 40-pin header mapping. Reference the RP2350 Datasheet for deep-dive register maps.
| Pin | Name | Type | Primary & Alternate Functions |
|---|---|---|---|
| 1 | GP0 | Digital | UART0 TX, I2C0 SDA, SPI0 RX |
| 2 | GP1 | Digital | UART0 RX, I2C0 SCL, SPI0 CSn |
| 3 | GND | Power | Ground |
| 4 | GP2 | Digital | I2C1 SDA, SPI0 SCK |
| 5 | GP3 | Digital | I2C1 SCL, SPI0 TX |
| 6 | GP4 | Digital | UART1 TX, I2C0 SDA, SPI0 RX |
| 7 | GP5 | Digital | UART1 RX, I2C0 SCL, SPI0 CSn |
| 8 | GND | Power | Ground |
| 9 | GP6 | Digital | I2C1 SDA, SPI0 SCK |
| 10 | GP7 | Digital | I2C1 SCL, SPI0 TX |
| 11 | GP8 | Digital | UART1 TX, I2C0 SDA, SPI1 RX |
| 12 | GP9 | Digital | UART1 RX, I2C0 SCL, SPI1 CSn |
| 13 | GND | Power | Ground |
| 14 | GP10 | Digital | I2C1 SDA, SPI1 SCK |
| 15 | GP11 | Digital | I2C1 SCL, SPI1 TX |
| 16 | GP12 | Digital | UART0 TX, I2C0 SDA, SPI1 RX |
| 17 | GP13 | Digital | UART0 RX, I2C0 SCL, SPI1 CSn |
| 18 | GND | Power | Ground |
| 19 | GP14 | Digital | I2C1 SDA, SPI1 SCK |
| 20 | GP15 | Digital | I2C1 SCL, SPI1 TX |
| 21 | GP16 | Digital | UART0 TX, I2C0 SDA, SPI0 RX |
| 22 | GP17 | Digital | UART0 RX, I2C0 SCL, SPI0 CSn |
| 23 | GND | Power | Ground |
| 24 | GP18 | Digital | I2C1 SDA, SPI0 SCK |
| 25 | GP19 | Digital | I2C1 SCL, SPI0 TX |
| 26 | GP20 | Digital | UART1 TX, I2C0 SDA, SPI0 RX |
| 27 | GP21 | Digital | UART1 RX, I2C0 SCL, SPI0 CSn |
| 28 | GND | Power | Ground |
| 29 | GP22 | Digital | I2C1 SDA, SPI0 SCK |
| 30 | RUN | Control | Reset (Active LOW) |
| 31 | GP26 | Analog/Dig | ADC0, I2C1 SCL, SPI1 SCK |
| 32 | GP27 | Analog/Dig | ADC1, I2C1 SDA, SPI1 TX |
| 33 | AGND | Power | Analog Ground |
| 34 | GP28 | Analog/Dig | ADC2, I2C1 SCL, SPI1 TX |
| 35 | ADC_VREF | Analog | ADC Voltage Reference (3.3V) |
| 36 | 3V3(OUT) | Power | Regulated 3.3V Output |
| 37 | 3V3_EN | Control | Enable for onboard regulator |
| 38 | GND | Power | Ground |
| 39 | VSYS | Power | Main System Input (1.8V - 5.5V) |
| 40 | VBUS | Power | USB 5V Input |
Wire Color Standards & Faded Silkscreen Recovery
When wiring sensors to the Pico 2 W, you will encounter conflicting wire color standards depending on your region and the component manufacturer. Furthermore, the Pico's white silkscreen easily wears off or gets obscured by flux during heavy soldering.
Regional and Vendor Wiring Standards
While power wiring follows strict electrical codes, data bus wiring relies on vendor conventions. Here is how to interpret the wires in your bin:
| Standard | Region / Origin | VCC / Power | GND | Data / Signal Colors |
|---|---|---|---|---|
| IEC 60446 / NEC | Global / North America (Mains & DC Power) | Red (DC+), Brown (AC Line) | Black (DC-), Blue (AC Neutral) | Green/Yellow (Earth Ground only) |
| Adafruit STEMMA QT | US / Global Hobbyist (I2C Focus) | Red (3.3V or 5V) | Black | Blue (SDA), Yellow (SCL) |
| SparkFun Qwiic | US / Global Hobbyist (I2C Focus) | Red (3.3V strictly) | Black | Blue (SDA), Yellow (SCL) |
| Generic Dupont SPI | China / Global Bulk Ribbons | Red | Black | Blue (MOSI), Green (MISO), Yellow (SCK), Orange (CS) |
Recovering Faded Pin Markings
If your Pico 2 W silkscreen is unreadable, you can reliably identify Pin 1 using two physical markers:
- The Square Pad: Flip the board over. The through-hole pad for Pin 1 is square, while all other pads (2-40) are perfectly round.
- USB Orientation: Hold the board with the Micro-USB port facing away from you (pointing up). The left-hand column contains the odd pins (1, 3, 5... 39) starting from the top. The right-hand column contains the even pins (2, 4, 6... 40).
Rows Makers Get Wrong: Power, ADC, and Reset Gotchas
The RP2350 is a massive silicon upgrade over the RP2040, but it introduces new edge cases that catch makers migrating from the Pico 1 W.
VSYS vs. VBUS Routing
Pin 40 (VBUS) is directly tied to the Micro-USB 5V line. Pin 39 (VSYS) is the main system input, feeding the onboard RT6154B buck-boost converter. If you are powering the Pico 2 W from a 3.7V LiPo or a 12V step-down buck converter, always inject power into VSYS. Never backfeed 5V into the 3V3(OUT) pin (Pin 36); the RP2350's power management IC (PMIC) is not designed to be reverse-driven and will fail catastrophically.
The RP2350 ADC Reality
The original Pico W had a notoriously noisy ADC, and ADC3 was hardcoded to read VSYS/3. The Pico 2 W fixes this. The RP2350 features a significantly improved 12-bit ADC with much lower noise floors. However, the absolute maximum voltage on GP26, GP27, and GP28 remains 3.3V. Unlike some ESP32 variants that tolerate 5V on certain ADC pins via internal dividers, the RP2350 has no internal 5V tolerance. Feeding 5V into GP26 will instantly destroy the ADC channel.
The RUN Pin (Pin 30)
RUN is an active-LOW reset pin. It is pulled high internally. If you are wiring a physical reset button, wire it between RUN and GND. A common mistake is wiring a switch that accidentally shorts RUN to 3V3, which does nothing, or leaving it floating in a high-EMI environment, causing random reboots.
Where are the Wireless Pins?
The Infineon CYW43439 module uses WL_GPIO0, WL_GPIO1, and WL_GPIO2. These are not broken out to the 40-pin header. They are routed internally on the PCB directly to the RP2350. You do not need to wire them to use Wi-Fi or Bluetooth; you simply call them in your MicroPython or C++ SDK via the wireless library.
Frequently Asked Questions
Can I use original Pico W HATs and shields with the Pico 2 W pinout?
Yes, physically the 40-pin header spacing and GPIO assignments (GP0 through GP28) are 100% identical to the Pico 1 W. Any shield that plugs into the standard Pico footprint will mate perfectly. However, if the shield relies on the exact timing or the buggy ADC behavior of the original RP2040, you may need to update the firmware or adjust ADC sampling averages in your code to account for the RP2350's faster clock speeds and cleaner ADC readings.
Why does my Raspberry Pi Pico 2 W ADC read erratic values on GP26?
Even with the RP2350's improved silicon, erratic ADC readings on GP26/GP27/GP28 are almost always caused by a missing or noisy ADC_VREF (Pin 35). Ensure Pin 35 is cleanly tied to 3V3(OUT) with a 100nF decoupling capacitor to AGND (Pin 33). If you are reading a high-impedance sensor (like a voltage divider with >10kΩ resistors), the RP2350's internal sampling capacitor cannot charge fast enough. Add a 10kΩ pull-down or a dedicated op-amp buffer to the ADC input.
How do I identify the Pico 2 W wireless module pins for external antennas?
You cannot easily wire an external antenna to the Pico 2 W. The board uses a highly tuned PCB trace antenna located on the left side of the board (the "keep-out" zone near the Infineon silver shield). Desoldering the shield to access the RF trace for a U.FL connector requires hot-air rework and will almost certainly detune the impedance, destroying your Wi-Fi range. If you need an external antenna, buy a dedicated RP2350 board with a pre-soldered U.FL/IPEX connector rather than modifying the Pico 2 W.
What is the maximum current draw from the 3V3(OUT) pin on the Pico 2?
The Pico 2 W uses an updated PMIC that is technically capable of higher current than the original Pico. However, the official Raspberry Pi hardware documentation still recommends limiting continuous draw from the 3V3(OUT) pin to 300mA. This limit is dictated not by the regulator chip itself, but by the thermal dissipation limits of the PCB traces and the via stitching on the 4-layer board. For high-current peripherals like 5V LED strips or heavy servo loads, power them directly from the VBUS (5V) pin and use external logic-level MOSFETs.
