Basic Introduction

ColorEasyPICO2 is a lightweight, powerful, and easy-to-use development board based on the Raspberry Pi RP2350A microcontroller, designed for embedded development, IoT projects, and educational purposes. It integrates a rich set of functional modules, providing a strong creative platform for makers, developers, and engineers, whether for rapid prototyping or creating innovative projects.

Basic parameters

Pinouts

on-board resource

RP2350 Chip Introduction

RP2350 System Overview

RP2350A Pin Description

Only screenshots show QFN-60 (RP2350A) used in this project.

Name	Description
GPIOx	General-purpose digital input and output. Can connect internal peripherals or be controlled directly from software.
GPIOx/ADCy	General-purpose digital input and output, with analogue-to-digital converter function. The RP2350 ADC has an analogue multiplexer to select these pins for voltage sampling.
QSPIx	Interface to SPI, Dual-SPI, or Quad-SPI flash or PSRAM device. Can be used as software-controlled GPIOs if not required for flash access.
USB_DM and USB_DP	USB controller, supporting Full Speed device and Full/Low Speed host. Requires 27Ω series termination resistor on each pin. Bus pullups and pulldowns are provided internally. Can be used as GPIOs if USB is not required.
XIN and XOUT	Connect a crystal to RP2350’s crystal oscillator. XIN can also be a CMOS clock input. Defaults to 12 MHz crystal or clock input for USB bootloader. Configurable via OTP.
RUN	Global asynchronous reset pin. Reset when driven low, run when driven high. Can be tied directly to IOVDD if no external reset is needed.
SWCLK and SWDIO	Access to internal Serial Wire Debug bus for debug access and code download.
GND	Single external ground connection, bonded to internal ground pads.
IOVDD	Power supply for digital GPIOs, nominal voltage 1.8V to 3.3V.
USB_OTP_VDD	Power supply for internal USB Full Speed PHY and OTP storage, nominal voltage 3.3V.
ADC_AVDD	Power supply for analogue-to-digital converter, nominal voltage 3.3V.
QSPI_IOVDD	Power supply for QSPI IOs, nominal voltage 1.8V to 3.3V.
VREG_AVDD	Analogue power supply for internal core voltage regulator, nominal voltage 3.3V.
VREG_PGND	Power-ground connection for internal core voltage regulator, tie to ground externally.
VREG_LX	Switched-mode output for internal core voltage regulator, connected to an external inductor. Max current 200 mA, nominal voltage 1.1V after filtering.
VREG_VIN	Power input for internal core voltage regulator, nominal voltage 2.7V to 5.5V.
VREG_FB	Voltage feedback for internal core voltage regulator, connect to filtered VREG output (e.g., to DVDD, if used to supply DVDD).
DVDD	Digital core power supply, nominal voltage 1.1V. Must be connected externally, either to the voltage regulator output or an external board-level power supply.

Hardware Design

Power Supply

For the TYPE-C part:

Input 5V power VBUS through type-c, and some power supplies have power spoofing functions. To ensure that power modules with this function can output 5V correctly, 5.1K resistors are added in CC1 and CC2, namely R2 and R8.
The two 27-ohm resistors R4 and R5 are referenced from the USB section of the Raspberry Pi RP2350 design guide. USB_D+ and USB_D- are connected to the USB pins of the main control RP2350. USB2_D- and USB2_D+ are USB test points for convenient factory batch burning tests, allowing for quick batch burning through a test rack.
D2 and D3 are ESD devices that protect the USB line from electrostatic damage.
D1 is a reverse polarity protection diode, selected with a forward conduction voltage drop of 310mV at 1A. The voltage output from VBUS through this diode is VSYS.
R3 and R6 form a USB check circuit, which is essentially a voltage divider circuit that reduces VBUS to below 3.3V for the main control RP2350 to check the level through GPIO24. If GPIO24 is high, it indicates that TYPE-C has input; if GPIO24 is low, it indicates that TYPE-C has no input.

5V buck 3.3V part

Through an LDO device 'ME6217C33M5G', the input VSYS is reduced to 3.3V, which will be the core voltage of the master RP2350. The LDO has a maximum input of 7V and an output current of 800mA; for additional details, please refer to its data sheet.
C12\C13\C10\C11 are all power filters. It is suggested that 100nF and 10uF are combined to form a simple filter.
PWR_LED represents the power LED power lamp, through a 2k resistance for current limiting. The measured LED in the case of access 2K current limiting resistor, brightness is not dazzling nor dim, just appropriate.
R11 is a pull-up resistor, which is used to set the CE terminal of pin 3 of the LDO device to high by default, and the LDO will work normally when the CE terminal is high. Attention should be paid to the signal of 3V3_EN, which is connected to the external pin row. When 3V3_EN is connected to the low level, the LDO output device will stop working, so the user needs to input 3.3V voltage through the pin row.

Main Control

Each power input pin of the RP2350 has a corresponding filter capacitor of 100nF.
IOVDD is 3.3V, and DVDD is 1.1V, with 1.1V output from the internal voltage regulator of the RP2350. It requires a 3.3uH inductor, which must be a special polarized inductor provided in the RP2350 design guide by Raspberry Pi. The layout of the inductor must match the reference design exactly; otherwise, it will affect the power performance of the RP2350.

Memory

The memory used is W25Q32, with a memory size of 4MB.
A 100nF filter capacitor is added at the power input.
R13 is not used and not mounted.
R14 is a short-circuit prevention resistor connected to a BOOT button, which can control the RP2350 to enter upgrade mode and refresh firmware. If R14 is not added, pressing the BOOT button while QSPI_SS is high will trigger a short circuit.

Clock

The RP2350 uses a 12MHz passive crystal oscillator. The selected crystal device is the corresponding reference device in the RP2350 design guide: ABM8-272-T3.
C23 and C22 are matching capacitors of 15pF for assisting the crystal to oscillate and ensuring stable output

Reset

In the original RP23050 reference design, this button is not present. The function of this button is to make the RP2350 reset and work again. At the same time, through the operation of reset button and BOOT button, it is more convenient for users to let RP2350 enter the upgrade mode, and also convenient for users to debug.

LED

The GPIO25 pin of the RP2350 is connected to an LED circuit. The current limiting resistor of 15K makes the brightness of the LED close to the brightness of the power lamp, which is indeed measured.

ADC

The onboard ADC function test circuit. For details, please see:

I/O eliculation

RUN is the master control reset pin, when the input is low, let the RP2350 reset and work again.

ADC_VREF is the external reference voltage input pin of the ADC function. If the accuracy of the onboard ADC is not high and the interference is large, please input a stable 3.3V reference voltage by yourself.

PCB design considerations

Please refer to the reference design layout in the RP2350 Design guide for the voltage regulator inductor of the master control. It is recommended to copy the layout directly.

The screen printing layer of the development board uses the special process of JLCPCB, color screen printing process. The characters, lines and pictures on the screen printing layer can be designed as color.

You can view the color printing effect through the 3D display function.

Development board use

MicroPython

Download firmware

Download the.uf2 file, which is the microPython firmware for PICO2. Download from:

MicroPython The latest official download address: https://micropython.org/download/RPI_PICO2/

Install firmware

Press and hold the BOOT button on the PICO2 development board, then plug the PICO2 into the USB port of the computer, and finally release the BOOT button. If this is done correctly, the computer shows that a USB key has been inserted and recognizes it as a mass storage device.

Put the downloaded MicroPython UF2 file into the RP2350 disk that your computer recognizes. Your PICO2 board will restart automatically and the MicroPython firmware will be installed.

Install IDE

Thonny is a simple yet powerful integrated development environment (IDE) specifically designed for beginners and educators. It provides a concise way to write, debug, and e x e c u t e program code.

Using Thonny, it is easy to write and run MicroPython code to control the PICOx development board. MicroPython is a stripped-down Python interpreter designed specifically for programming embedded devices. It provides a syntax that is easy to understand and write, making it easy for beginners and non-expert developers to get started.

In Thonny, MicroPython scripts can be created and edited, and then uploaded to the development board to run. Thonny also provides a set of debugging tools that help locate and fix errors in your code. We can set breakpoints in Thonny, step through the code, and monitor the values of variables to gain insight into how the program is running.

Overall, Thonny provides a friendly interface and powerful features that make it easier for you to control the development board using the MicroPython programming language. Whether you're a beginner or already have some experience, Thonny is a tool worth trying.

Thonny to download：https://thonny.org/

Note that the mouse must be moved over windows to display the corresponding information

All the way to the default installation. (Recommended to change the installation path)

verification

Connect the development board to the computer through the type-c cable and open Thoony's Configure interpreter. In the interpreter, select MicroPython(universal).

Port select the port connected to the PICO2 development board; (Each person's port is different, please test which port is connected to the PICO2 development board by yourself)

Lighting test

In Thonny, create a new file called test.py and save it to any path.

Write the following code in the file:

from machine import Pin
import time

# Initialize the GPIO 25 pin to output mode
led = Pin(25, Pin.OUT)

while True:
    # open LED
    led.value(1)
    time.sleep(1)  #wait 1S

    # open LED
    led.value(0)
    time.sleep(1)  # wait 1S

After setting the configuration interpreter, click the STOP key, and the MicroPython version appears in the shell below indicating that the connection to the development board is successful;

Click the green arrow to start running the current script code. After successful operation, you can see the onboard LED flashing;

Arduino

Download the required Package profile package_rp2040_index.json for Arduino. Put it in user folder \AppData\Local\Arduino15or create one if you don't already have one.

For example, if my computer username is win, my path would be:

C:\Users\win\AppData\Local\Arduino15

The AppData folder is a hidden folder that needs to be configured by the user to show hidden folders

Download RP2040-version.zip, making sure the versioning is correct. Download address：https://github.com/earlephilhower/arduino-pico/releases

> I am currently using 4.1.1

Download the support package, all in ~\Arduino15\staging\packages 。

Open the Arduino Add-on board Manager URL. Arduino IDE > File > Preferences > Other board Manager URL Add the board package address:

https://github.com/earlephilhower/arduino-pico/releases/download/global/package_rp2040_index.json

Install the board package: Arduino IDE > Tools > Board > Board Manager, search for RP2350 and install the Raspberry Pi Pico/RP2040/RP2350 board from Earle F. Philhower, III.

Choose the same version number as the board package you downloaded offline

verification

The code:

// Define the GPIO pin connected to the LED
const int ledPin = 25;

void setup() {
  // Initialize the GPIO pin to output mode
  pinMode(ledPin, OUTPUT);
}

void loop() {
  // Turn on the LED
  digitalWrite(ledPin, HIGH);
  // wait 1s
  delay(1000);
  // Turn off the LED
  digitalWrite(ledPin, LOW);
  // wait 1s
  delay(1000);
}

Configuration:

Please use the RP2350 port recognized by your computer for COM port.

Burning code

When uploading the burning program for the first time, the development board needs to enter the upgrade mode, and the upgrade mode requires two methods:

You need to hold down the BOOT key, and then press the RST key until the computer pops up "inserted a USB key", you can release the hand.
When the development board is disconnected from the power supply, press and hold the BOOT key, and then access the TYPE-C data cable. At this time, the normal computer will pop up 'inserted a U disk', and you can release your hand at this time.

Once you're in upgrade mode, click the upload button on the arduino, and the program should be burned to the board. After the first upload, you normally don't need to do this because the arduino-pico core has auto-reset support. Just select the corresponding serial port from Tools -> Ports menu of Arduino (this setting will remain the same and will not need to be modified for multiple uploads). Such a choice allows the automatic reset tool to identify the correct device for reset. Your program should be uploaded and run when the upload button is clicked.

But in some cases, the PICO's USB port won't respond to auto-reset requests, according to officials. If that happens, simply go back into upgrade mode and try again.

Other Instructions

Zadig

Zadig can help users load generic drivers to solve the problem of devices not connecting to the computer, ensuring that peripherals can be accessed normally. Click Options → List All Devices, and be careful not to select system drivers when modifying.

BootLoader mode

RP2 Boot(interface 0) → USB Serial(CDC)
RP2 Boot(interface 1) → WinUSB

Normal mode

Raspberry Pi Pico(interface 0) → USB Serial(CDC)

If USB connection transfer does not work and the RP2350 disk manager or serial number does not pop up:
- Check if the BOOT button is not pressed or has been released in the middle;
- TYPE C must be a data cable (charging cable without data transfer function), and TYPE-C's DP/DN is not connected properly (cold solder);
- The crystal oscillator is not oscillating (cold solder or damaged).
If the device manager cannot recognize the device/unknown USB device (device descriptor request failed) after burning the initial UF2 firmware:
- Drag and drop flash_nuke.uf2 to clear the firmware, removing the original content from Flash, and then burn the initial UF2 firmware again;
- The RP2350 chip may be cold soldered or damaged; when soldering the QFN package, be sure to tin the pins first before soldering or heating.
Using Zadig causes the Pico in bootloader mode not to enumerate as a storage device:
- Find all RP2 boot drivers in the device manager;
- Right-click to select "Uninstall Device," checking "Delete the driver software for this device" (if prompted);
- Click uninstall, ensuring all RP2-related boot drivers are uninstalled.