pimoroni RP2350 Pico 2

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Dense context for pasting into a model prompt — addresses, pinout, voltages, tolerances and the vendor's reference circuit.

PART: Raspberry Pi Pico 2, order code SC1631, a 51 x 21 x 1 mm single-sided board built on the RP2350A (QFN-60): dual Arm Cortex-M33 or RISC-V Hazard3 cores at up to 150 MHz, 520 kB multi-bank SRAM, 4 MB QSPI flash (Winbond W25Q32RV), an Abracon ABM8-272-T3 crystal, micro-USB B, a BOOTSEL button and a 3-pin Arm SWD port on the lower edge. Peripherals: 2 x UART, 2 x I2C, 2 x SPI, 16 PWM channels, 3 PIO blocks with 12 state machines, a 12-bit 500 ksps ADC, USB 1.1 device or host, and two timers with four alarms plus an AON timer. The 40 pins are 2.54 mm pitch with 1 mm holes and are also castellation-edged so the board can be reflowed down as a module; four 2.1 mm mounting holes.
ADDRESSES: none. The board carries no I2C device of its own, so there is nothing to scan for on either bus - any address on SDA/SCL belongs to whatever you wire to the header.
PINOUT: 40 pads numbered as Raspberry Pi prints them, 1-20 down the left edge and 40-21 down the right, so pad 1 (GP0) and pad 40 (VBUS) are at the same end: 1 GP0, 2 GP1, 3 GND, 4 GP2, 5 GP3, 6 GP4, 7 GP5, 8 GND, 9 GP6, 10 GP7, 11 GP8, 12 GP9, 13 GND, 14 GP10, 15 GP11, 16 GP12, 17 GP13, 18 GND, 19 GP14, 20 GP15, 21 GP16, 22 GP17, 23 GND, 24 GP18, 25 GP19, 26 GP20, 27 GP21, 28 GND, 29 GP22, 30 RUN, 31 GP26 (ADC0), 32 GP27 (ADC1), 33 AGND, 34 GP28 (ADC2), 35 ADC_VREF, 36 3V3(OUT), 37 3V3_EN, 38 GND, 39 VSYS, 40 VBUS. That is 26 GPIO, 7 ground pads plus AGND, and the six other power and reset pins Raspberry Pi lists as the 40-pin interface. GPIO0-GP22 are digital only; GPIO26, GPIO27 and GPIO28 double as ADC0, ADC1 and ADC2.
SUPPLY: VBUS is 5 V +/-10% from micro-USB and is fed through the Schottky diode D1 to VSYS; VSYS accepts 1.8 V to 5.5 V and drives an RT6150 buck-boost SMPS that holds a fixed 3.3 V, so one lithium-ion cell or 3 x AA cells run the board directly. 3V3(OUT) can power external circuitry but Raspberry Pi recommends keeping that load under 300 mA. 3V3_EN is pulled up to VSYS by 100 kOhm and shorting it to ground disables the rail. Measured VBUS current on the vendor's own tables: 233 uA in low-power state P1.0, 148 uA in P1.7, 388 uA with RUN held low, 12.4 mA running hello_serial, 12.7 mA running hello_usb, 9.4 mA on CoreMark single-core. Operating range -20 C to +85 C including self-heating, with 70 C the recommended maximum ambient.
LOGIC LEVEL: fixed at 3.3 V. The RP2350 itself is rated 1.8-3.3 V I/O, but Raspberry Pi states plainly that Pico 2 IO voltage is fixed at 3.3 V, so a 5 V logic source needs level shifting. GPIO26-29 carry an internal reverse diode to IOVDD and the datasheet's stated consequence is that their input must not exceed IOVDD plus about 300 mV, and that driving them while the RP2350 is unpowered leaks through that diode into the 3.3 V rail. GPIO0-25 and the SWD pins have no such restriction and can safely be driven while the board is unpowered.
REFERENCE CIRCUIT: the board fits the two 27 Ohm USB series resistors, D1 from VBUS to VSYS, and an R-C divider of R5, R6, R16 and C3 across VSYS giving VSYS/3 on ADC channel 3; R10 and R1 pull VBUS to 0 V when it is absent; the SMPS enable pin has its 100 kOhm pull-up to VSYS; ADC_AVDD is the 3.3 V rail filtered by 201 Ohm into 2.2 uF. To add a second supply, Raspberry Pi's own two options are a second Schottky diode into VSYS (power ORing, with a diode drop) or a P-channel MOSFET with its gate on VBUS, for which it names the Diodes DMG2305UX (Vt max 0.9 V, Ron 100 mOhm at 2.5 V Vgs). If USB is the only source, VSYS and VBUS may be shorted to remove the diode drop. This datasheet publishes no pull-up values for SDA/SCL - the header has no I2C pull-ups fitted, so the user adds them.
TRAPS: (1) four GPIOs are taken by the board and are not on the header - GPIO29 is wired to measure VSYS/3 as ADC3, GPIO25 drives the user LED, GPIO24 senses VBUS presence, and GPIO23 drives the RT6150 power-save pin, so do not repurpose them. (2) USB host mode requires 5 V on the VBUS pad, not just a USB cable. (3) AGND (pad 33) is the analogue ground for GPIO26-29 and is separate from the digital grounds. (4) the ADC has no internal reference and uses its own supply, so its accuracy is the 3.3 V SMPS accuracy, and the ~150 uA the ADC draws through the 200 Ohm filter creates roughly a 30 mV offset. (5) test points TP4 (GPIO23/SMPS PS) and TP7 (1V1) are marked do not use, and TP5 swings only to the LED forward voltage. (6) the USB boot ROM cannot be overwritten, so a board cannot be bricked out of mass-storage mode.