RP2350 explained

RP2350 is a 32-bit dual ARM Cortex-M33 and Hazard3 RISC-V microcontroller integrated circuit by Raspberry Pi Ltd.^[1] In August 2024, it was released as part of the Raspberry Pi Pico 2 board.^[2]

Overview

Announced on 8 August 2024, the RP2350 is the second microcontroller designed by Raspberry Pi Ltd, after the RP2040. The microcontroller is low cost, with the Raspberry Pi Pico 2 being introduced at and the RP2350 itself costing as little as in bulk. The microcontroller is software-compatible with the RP2040 and can be programmed in assembly, C, C++, Free Pascal, Rust, MicroPython, CircuitPython, and other languages.

The RP2350 comes in four versions, which are identified by the number of cores (2), a numeral loosely correlated to the core type^[3] (3), log₂ of the number of 16 KB RAM blocks (5), log₂ of the number of 128 KB flash storage blocks (0 or 4), and a letter denoting package type (A or B):^[4]

• RP2350A - 30 GPIO in a 7 × 7 mm QFN-60EP package (EP means exposed pad in center)
• RP2350B - 48 GPIO in a 10 × 10 mm QFN-80EP package (EP means exposed pad in center)
• RP2354A - same package as RP2350A (above) includes 2 MB QSPI NOR flash
• RP2354B - same package as RP2350B (above) includes 2 MB QSPI NOR flash

Note: inside the "54" IC packages, a NOR flash die is stacked on top of the microcontroller die, then connected to its QSPI bus and first chip select.

At announcement time, seventeen other manufacturers had products expected to be available within a month.

Features

The chip is a 5.3mm2 silicon die in a 7 × 7 mm QFN-60EP or 10 × 10 mm QFN-80EP surface-mount device (SMD) package.

• Key features:
  • 150 MHz dual ARM Cortex-M33 (ARMv8-M) and Hazard3 RISC-V (RV32IMAC+) cores
    • Each Cortex-M33 core includes DSP instructions, single-precision (SP) floating-point instructions, and a simplified double-precision floating-point coprocessor provides add, subtract, multiply, divide, square root.
  • 520 KB SRAM in ten concurrently accessible banks
  • 8 KB of one-time-programmable (OTP) memory
  • QSPI bus controller supports external flash and PSRAM
    • Optional in-package 2 MB QSPI NOR flash connected to first chip select
  • DMA controller, 16 channel, 4 IRQ
  • AHB crossbar, fully-connected
  • On-chip switched-mode power supply and programmable low-dropout regulator (LDO) to generate core voltage
  • Two on-chip PLLs to generate 48 MHz USB and 150MHz core clocks
  • RP2350A has 30 GPIO pins, of which four can optionally be used as analog inputs, RP2350B has 48 GPIO pins where eight can be used as analog inputs.
  • Optional boot signing with protected OTP storage
  • Hardware SHA-256 accelerator
  • Hardware random number generator (TRNG)
• Peripherals:
  • One USB 1.1 (LS & FS) controller and PHY, host and device support, 1.5 Mbps (Low Speed) and 12 Mbps (Full Speed).
  • Two UART controllers.
  • Two SPI controllers.
  • One QSPI (quad SPI) controller, supports 1 / 2 / 4-bit SPI transfers, 2 chip selects.
  • Two I²C controllers.
  • One HSTX (high-speed serial transmit) controller, output-only. This is meant for digital video output.
  • 12 PIO (programmable input–output) state machines.
  • 24 PWM channels.
  • 4/8-channel 12-bit 500-Ksps SAR ADC, extra channel is connected to internal temperature sensor. QFN-60EP package has 4 channels, QFN-80EP package has 8 channels.

Family comparison

The following is a simplified comparison of the RP2040 and RP2350 microcontroller families.

Feature		RP2350
Package	QFN-56EP	QFN-60EP or QFN-80EP
CPU Cores		Two ARM Cortex-M33 (FPU), two Hazard3 RISC-V
CPU Clock		150 MHz
SRAM	264 KB, 6 banks	520 KB, 10 banks
Flash	None	2 MB (inside x54 parts)
OTP	None	8 KB
DMA	12 chan, 2 IRQ	16 chan, 4 IRQ
PIO	8	12
PWM	16	24
ADC	4-chan 12-bit ADC	4-chan 12-bit (QFN-60EP), 8-chan 12-bit (QFN-80EP)
DAC	None	None
HSTX	None	One
Engines	?	RNG, SHA-256

GPIO hardware issue

The RP2350 chip was released with errata RP2350-E9, documenting a "Latching behaviour on Bank 0 GPIO pull-down resistors", which was later updated to "Increased leakage current on Bank 0 GPIO when pad input is enabled" due to multiple reports from users,^[5] such as developers of the Bus Pirate.

The defect causes pins configured as inputs to source about 120 μA when the input voltage is between logical low and logical high, pulling them to about 2.2V.^[6]

Luke Wren, one of the engineers working on RP2350 has stated that the supplier responsible for the pad circuitry has provided a faulty design. "We didn't modify the pad, we asked the vendor to modify their own pad. There was one particular structure on the RP2040 FT pad that limited its tolerance, but on inspection the modified layout we got back was a completely different circuit."^[7]

See also

• Arduino – a popular microcontroller board family
• ESP32 – a series of low-cost, low-power system on a chip microcontrollers with integrated Wi-Fi and dual-mode Bluetooth.
• STM32 – a family of 32-bit microcontroller integrated circuits

External links

• Official webpage
• Datasheet

Notes and References

1. Web site: RP2350 . Raspberry Pi.
2. Web site: Upton . Eben . 8 August 2024 . Raspberry Pi Pico 2, our new $5 microcontroller board, on sale now . 8 August 2024 . Raspberry Pi.
3. Web site: RP2350 Datasheet. Raspberry Pi.
4. Web site: Pounder . Les . What's inside the Raspberry Pi Pico 2's RP2350? . Tom's Hardware . 25 August 2024 . en . 23 August 2024.
5. Web site: RP2350-E9 Erratum: can get "stuck" at 2V state even without pulldown . GitHub . 2024-09-04.
6. Web site: RP2350 Datasheet . Raspberry Pi Ltd . 7 September 2024.
7. Web site: Wren . Luke . Luke Wren (@[e-mail]) . types.pl. 25 August 2024 .