Overview

RP2350-GEEK

SWD/UART/USB-A

Introduction

RP2350-GEEK is a development board designed for geeks by Waveshare. It comes with a USB-A port, 1.14-inch LCD screen, TF card slot, and other peripherals. Depending on the firmware used, it can provide SWD interface, UART interface, and I2C interface, offering endless possibilities for your projects.

Features

RP2350 microcontroller chip designed by Raspberry Pi
Adopts unique dual-core and dual-architecture design, equipped with dual-core ARM Cortex-M33 processor and dual-core Hazard3 RISC-V core processor, flexible clock running up to 150 MHz
Built-in 520KB of SRAM and 16MB of on-chip Flash
Onboard 1.14inch 240×135 pixels 65K color IPS LCD display
Onboard 3PIN SWD interface for connecting to the target board to be debugged
- Standard CMSIS-DAP interface, applicable for most ARM-based microcontrollers
- Works with OpenOCD and other tools supporting CMSIS-DAP
- Adopts the Raspberry Pi 3PIN Debug Connector Specification
Onboard 3PIN UART interface for USB serial adapter
Onboard 4PIN I2C port for the testing target board
Equipped with plastic case and cables
Open-source firmware, more convenient to upgrade

Dimensions

Pico Getting Started

Firmware Download

MicroPython Firmware Download

C_Blink Firmware Download

Basic Introduction

Raspberry Pi Pico Basics

MicroPython Series

Install Thonny IDE

In order to facilitate the development of Pico/Pico2 boards using MicroPython on a computer, it is recommended to download the Thonny IDE

Download Thonny IDE and follow the steps to install, the installation packages are all Windows versions, please refer to Thonny's official website for other versions
After installation, the language and motherboard environment need to be configured for the first use. Since we are using Pico/Pico2, pay attention to selecting the Raspberry Pi option for the motherboard environment

Configure MicroPython environment and choose Pico/Pico2 port
- Connect Pico/Pico2 to your computer first, and in the lower right corner of Thonny left-click on the configuration environment option --> select Configture interpreter
- In the pop-up window, select MicroPython (Raspberry Pi Pico), and choose the corresponding port

Flash Firmware

Click OK to return to the Thonny main interface, download the corresponding firmware library and burn it to the device, and then click the Stop button to display the current environment in the Shell window
Note: Flashing the Pico2 firmware provided by Micropython may cause the device to be unrecognized, please use the firmware below or in the package
- Pico firmware library
- Pico2 firmware library
How to download the firmware library for Pico/Pico2 in windows: After holding down the BOOT button and connecting to the computer, release the BOOT button, a removable disk will appear on the computer, copy the firmware library into it
How to download the firmware library for RP2040/RP2350 in windows: After connecting to the computer, press the BOOT key and the RESET key at the same time, release the RESET key first and then release the BOOT key, a removable disk will appear on the computer, copy the firmware library into it (you can also use the Pico/Pico2 method)

MicroPython Series Tutorials

【MicroPython】 machine.Pin class function details
【MicroPython】machine.PWM class function details
【MicroPython】machine.ADC class function details
【MicroPython】machine.UART class function details
【MicroPython】machine.I2C class function details
【MicroPython】machine.SPI class function details
【MicroPython】rp2.StateMachine class function details

C/C++ Series

For C/C++, it is recommended to use Pico VS Code for development. This is a Microsoft Visual Studio Code extension designed to make it easier for you to create, develop, and debug projects for the Raspberry Pi Pico series development boards. No matter if you are a beginner or an experienced professional, this tool can assist you in developing Pico with confidence and ease. Here's how to install and use the extension.

Official website tutorial: https://www.raspberrypi.com/news/pico-vscode-extension/
This tutorial is suitable for Raspberry Pi Pico, Pico2 and the RP2040 and RP2350 series development boards developed by Waveshare
The development environment defaults to Windows11. For other environments, please refer to the official tutorial for installation

Install VSCode

First, click to download pico-vscode package, unzip and open the package, double-click to install VSCode

Note: If vscode is installed, check if the version is v1.87.0 or later

Install Extension

Click Extensions and select Install from VSIX
Select the package with the vsix suffix and click Install
Then vscode will automatically install raspberry-pi-pico and its dependency extensions, you can click Refresh to check the installation progress
The text in the right lower corner shows that the installation is complete. Close VSCode

Configure Extension

Open directory C:\Users\username and copy the entire .pico-sdk to that directory
The Copy is completed

Open vscode and configure the paths for the Raspberry Pi Pico extensions

The configuration is as follows:

Cmake Path:
${HOME}/.pico-sdk/cmake/v3.28.6/bin/cmake.exe

Git Path:
${HOME}/.pico-sdk/git/cmd/git.exe    

Ninja Path:
${HOME}/.pico-sdk/ninja/v1.12.1/ninja.exe

Python3 Path:
${HOME}/.pico-sdk/python/3.12.1/python.exe

New Project

The configuration is complete, create a new project, enter the project name, select the path, and click Create to create the project
To test the official example, you can click on the Example next to the project name to select
The project is created successfully
Select the SDK version
Select Yes for advanced configuration
Choose the cross-compilation chain, 13.2.Rel1 is applicable for ARM cores, RISCV.13.3 is applicable for RISCV cores. You can select either based on your requirements
Select default for CMake version (the path configured earlier)
Select default for Ninjaversion
Select the development board
Click Complie to compile
The uf2 format file is successfully compiled

Import Project

The Cmake file of the imported project cannot have Chinese (including comments), otherwise the import may fail
To import your own project, you need to add a line of code to the Cmake file to switch between pico and pico2 normally, otherwise even if pico2 is selected, the compiled firmware will still be suitable for pico
set(PICO_BOARD pico CACHE STRING "Board type")

Update Extension

The extension version in the offline package is 0.15.2, and you can also choose to update to the latest version after the installation is complete

Arduino IDE Series

Install Arduino IDE

First, go to Arduino official website to download the installation package of the Arduino IDE.
Here, you can select Just Download.
Once the download is complete, click Install.

Notice: During the installation process, it will prompt you to install the driver, just click Install

Arduino IDE Interface

After the first installation, when you open the Arduino IDE, it will be in English. You can switch to other languages in File --> Preferences, or continue using the English interface.
In the Language field, select the language you want to switch to, and click OK.

Install Arduino-Pico Core in Arduino IDE

Open the Arduino IDE, click on the file in the top left corner, and select Preferences

Add the following link to the attached board manager URL, and then click OK

https://github.com/earlephilhower/arduino-pico/releases/download/4.0.2/package_rp2040_index.json

Note: If you already have an ESP32 board URL, you can use a comma to separate the URLs as follows:

https://dl.espressif.com/dl/package_esp32_index.json,https://github.com/earlephilhower/arduino-pico/releases/download/4.0.2/package_rp2040_index.json

Click Tools > Development Board > Board Manager > Search pico, as my computer has already been installed, it shows that it is installed

Upload Demo at the First Time

Press and hold the BOOTSET button on the Pico board, connect the pico to the USB port of the computer via the Micro USB cable, and release the button after the computer recognizes a removable hard disk (RPI-RP2).
Download the program and open D1-LED.ino under the arduino\PWM\D1-LED path
Click Tools --> Port, remember the existing COM, do not click this COM (the COM displayed is different on different computers, remember the COM on your own computer)
Connect the driver board to the computer using a USB cable. Then, go to Tools > Port. For the first connection, select uf2 Board. After uploading, when you connect again, an additional COM port will appear
Click Tools > Development Board > Raspberry Pi Pico > Raspberry Pi Pico or Raspberry Pi Pico 2
After setting it up, click the right arrow to upload the program

If issues arise during this period, and if you need to reinstall or update the Arduino IDE version, it is necessary to uninstall the Arduino IDE completely. After uninstalling the software, you need to manually delete all contents within the C:\Users\[name]\AppData\Local\Arduino15 folder (you need to show hidden files to see this folder). Then, proceed with a fresh installation.

Open Source Demos

MircoPython video demo (github)
MicroPython firmware/Blink demos (C)
Raspberry Pi official C/C++ demo (github)
Raspberry Pi official micropython demo (github)
Arduino official C/C++ demo (github)

Demo

C/C++ Demo

01-LCD

LCD refreshes an image and waits for 2.5 seconds
LCD refreshes GUI demo

02-picoprobe

This demo is based on the open-source program picoprobe
The RP2350-GEEK runs the picoprobe demo, which will emulate a USB TO SWD and USB TO UART device

Using the UART interface as a USB to serial tool, it can be used for device communication
Using the SWD interface as a debugging tool, when used with openocd, it can debug most ARM chips

For more information, please refer to the "PicoProbe Tutorial" below

03-FATFS

The demo is based on the open-source program no-OS-FatFS-SD-SDIO-SPI-RPi-Pico

The demo implements a command-line interface similar to busybox or DOS. It can mount a TF card, create and view files, and so on. The command “help” can be used to view all available commands

Note that the TF card file format is FAT32

Micropython Demo

01-LCD

How to Use

Upload all py and bmp files under the file to the RP2350-GEEK via thonny upload

Running Result

LCD displays the GUI screen, waits for a few seconds, and then displays the bmp image

02-SD

How to Use

Upload all py files under the file to the RP2350-GEEK via thonny and reset

Running Result

After the RP2350-GEEK is reset, it will automatically mount the TF to the SD file according to the boot.py program
Double-click to open the SD folder, and you can see the files stored in the TF card

LVGL Demos

C

Example Demonstration

The effect displayed in this example is to show an image through LVGL.

Demo Introduction

This example is used to test the LVGL widdet interaction and style beautification, etc.. For specific development of LVGL, please refer to LVGL development documentation.

Implement Function

In this example, DMA is used to transfer color data to the SPI bus, reducing CPU utilization, and controlling CPU usage to less than 50% and memory usage to less than 35% during simple interactions.
The example system clock is 200MHz. The peripheral clock frequency for SPI is set to match the system clock, and the LVGL library's dual buffer mechanism is utilized. Data transfer occurs in one buffer while the other buffer is rendering, ensuring smooth animation.
This example displays an image through LVGL, demonstrating the simple use of LVGL widget.

Compile and Run

Windows
- Refer to Windows Environment Setup Tutorial to complete the environment setup
- Open VS 2022 -> Tool -> Command Line -> Developer Powershell
- Set the absolute address of pico-sdk as PICO_SDK_PATH, for example, set pico-sdk address as "D:\pico\pico-sdk"
```
setx PICO_SDK_PATH "D:\pico\pico-sdk"
```
- Download the demo, enter the source code directory, if the build directory already exists, you can go directly into it. If not, you can create this directory:
```
mkdir build
cd build
```
- Execute cmake, automatically generate the Makefile file:
```
cmake -G "NMake Makefiles" ..
```
- Execute nmake to generate the executable file, and input the following content in the terminal:
```
nmake
```
  After compilation, it will generate a .uf2 formatted file.
- Press the onboard boot key, connect the board to the USB interface of the PC through a Micro USB cable. And then release the key, the PC will identify the pico as a removable driver. Finally, you need to copy the compiled file in .uf2 format to Pico.
Ubuntu
- Refer to Chapter 2. The SDK of Pico Getting Started to complete the environment setup
- Open a terminal, set the value of the environment variable PICO_SDK_PATH to the absolute path of pico-sdk, for example, if my pico-sdk path is "/home/pico/pico-sdk"
```
nano ~/.bashrc
#Add the following content at the last line
export PICO_SDK_PATH="/home/pico/pico-sdk"
```
- After setting, save and exit. The configuration takes effect
```
source ~/.bashrc
```
- Download the demo, enter the source code directory, if the build directory already exists, you can go directly into it. If not, you can create this directory:
```
mkdir build
cd build
```
- Execute cmake, it will generate Makefile file:
```
cmake ..
```
- Execute nmake to generate the executable file, and input the following content in the terminal:
```
nmake
```
  After compilation, it will generate a .uf2 formatted file.
- Press the onboard boot key, connect the board to the USB interface of the PC through a Micro USB cable. And then release the key, the PC will identify the pico as a removable driver. Finally, you need to copy the compiled file in .uf2 format to Pico.

Source Code Analysis

Source Code Structure

The source code of the LVGL library is at lib/lvgl of the project file folder, and the version used is "8.1". For secondary development, please refer to the development documentation corresponding to the used version.
The related settings for the LVGL library are at examples/inc/lv_conf.h of the project file folder, where you can set display refresh rates, system usage data, and so on.
The application code for the LVGL library is located in the project folder at examples/src/LVGL_example.c.

LVGL Initialization

Before using LVGL image library, you need to initialize LVGL.

The initialization function for the LVGL library
- Demo location: examples/src/LVGL_example.c
- Implementation function: Mainly used to initialize the hardware and structure variables required for LVGL.

LVGL_Init();

LVGL library core initialization
- Demo location: examples/src/LVGL_example.c

/*2.Init LVGL core*/
lv_init();

LVGL Run

The LVGL library calls the heartbeat function lv_tick_inc at regular intervals to notify LVGL of the elapsed time so that LVGL can update its internal time state and handle time-related tasks such as animations, timers, etc. The lv_task_handler function also needs to be called in the loop of the main function so that LVGL can handle events and tasks in time to ensure that the user interface responds and refreshes.

LVGL heartbeat interface
- Demo location: examples/src/LVGL_example.c
- Implementation method: It is necessary to ensure that the priority of lv_task_handler is lower than the priority of lv_tick_inc. Therefore, in this example, lv_tick_inc is called within the timer callback function.

//Timer callback function called every 5ms
add_repeating_timer_ms(5, repeating_lvgl_timer_callback, NULL, &lvgl_timer);

static bool repeating_lvgl_timer_callback(struct repeating_timer *t) 
{
    lv_tick_inc(5);
    return true;
}

LVGL Task Processor
- Demo location: examples/src/LCD_XinXX_LVGL_test.c
- Implementation method: To handle LVGL tasks, you need to regularly call lv_timer_handler(), in this example, it is called in the loop of the main function.

int main()
{
    ...
    while(1)
    {
      lv_task_handler();
      DEV_Delay_ms(5); 
      ...
    }

}

LVGL Display

To implement LVGL display, you must initialize a display driver and set the various properties of the display driver, such as color format, draw buffer, rendering mode, and display callback function. At each LV_DISP_DEF_REFR_PERIOD (set in lv_conf.h), LVGL detects if something has happened on the UI that needs to be redrawn. For example, a button is pressed, a chart is changed, an animation occurs, etc. When redrawing is needed, LVGL calls the display callback function to complete the drawing of the image in the refresh area.

LVGL display refreshing rate
- Demo location: examples/inc/lv_conf.h
- Setting method: In the lv_conf.h file, you can also set the display buffer refresh rate. You can modify this definition to change the screen refresh time.

#define LV_DISP_DEF_REFR_PERIOD  10 // Unit: ms, here is 10ms

LVGL display color setting
- Demo location: examples/inc/lv_conf.h
- Purpose of setting: Since the pixel color storage method constructed by the lv_color_t structure in its default state does not match the data to be transmitted in this example, direct transmission would result in color discrepancies in the displayed image.

#define LV_COLOR_16_SWAP 1

LVGL display related variable definition
- Demo location: examples/src/LVGL_example.c
- Implementation function: Define the display driver disp_drv, draw the buffer disp_buf. This example implements a double buffering mechanism, with the drawing buffer composed of buffers buf0 and buf1, both set to half the size of the screen display area, which can reduce jagged edges during large area refreshing while effectively improving screen refresh rate; when using a single buffer, it is best to set it to 10% of the screen display area, which can effectively reduce system usage but may result in noticeable jagged edges during large area refresh of image.

static lv_disp_drv_t disp_drv;
static lv_disp_draw_buf_t disp_buf;
static lv_color_t buf0[DISP_HOR_RES * DISP_VER_RES/2];
static lv_color_t buf1[DISP_HOR_RES * DISP_VER_RES/2];

LVGL display device registration
- Demo location: examples/src/LVGL_example.c
- Implementation function: According to the design requirements, improve the core structure variables of the LVGL library, initialize the display driver disp_drv, and set the drawing buffer, which is a simple array used by LVGL to render screen content. Once the rendering is ready, the content of the draw buffer will be sent to the display using the disp_drv_flush_cb function set in the display driver.

/*3.Init LVGL display*/
lv_disp_draw_buf_init(&disp_buf, buf0, buf1, DISP_HOR_RES * DISP_VER_RES / 2); 
lv_disp_drv_init(&disp_drv);    
disp_drv.flush_cb = disp_flush_cb;
disp_drv.draw_buf = &disp_buf;        
disp_drv.hor_res = DISP_HOR_RES;
disp_drv.ver_res = DISP_VER_RES;
lv_disp_t *disp= lv_disp_drv_register(&disp_drv);

LVGL display callback function
- Demo location: examples/src/LVGL_example.c
- Implementation function: Mainly complete the drawing of the image in the refresh area.

void disp_flush( lv_disp_drv_t *disp_drv, const lv_area_t *area, lv_color_t *color_p )
Parameters:
    lv_disp_drv_t *disp_drv： Displays driver structure pointers, which contain information about the display and function pointers. This parameter is often used to notify you that a refresh is complete
    const lv_area_t *area  : Region structure pointer, containing the position information of the area to be refreshed. In this demo, you can use it for creating TFT display window.
    lv_color_t *color_p    : Color structure pointer, indicating the color data to be displayed in the refresh area. In this demo, it reads the address as DMA input to transmit data to the SPI bus and completes the image drawing

LVGL display callback function implementation
- Demo location: examples/src/LVGL_example.c
- Implementation method: In this example, to maximize the reduction of processor utilization, DMA is used for color data transmission. color_p is set as the read address, and the SPI bus output data register is set as the write address.

static void disp_flush_cb(lv_disp_drv_t * disp, const lv_area_t * area, lv_color_t * color_p)
{
    LCD_SetWindows(area->x1, area->y1, area->x2+1, area->y2+1);
    DEV_Digital_Write(LCD_DC_PIN, 1);
    DEV_Digital_Write(LCD_CS_PIN, 0);
    dma_channel_configure(dma_tx,
                          &c,
                          &spi_get_hw(LCD_SPI_PORT)->dr, 
                          color_p, // read address
                          ((area->x2 + 1 - area-> x1)*(area->y2 + 1 - area -> y1))*2,
                          true);
}

LVGL refresh completion notification implementation
- Demo location: examples/src/LVGL_example.c
- Implementation function: The LVGL core needs to be notified after each image refresh is completed, so that LVGL can prepare the next refresh image for rendering.
- Implementation method: In this example, the completion of the DMA transmission is notified in the interrupt service function for LVGL image refresh. If a blocking notification mechanism is used, it is not possible to utilize the double buffering mechanism to increase the refresh rate.

static void dma_handler(void)
{
    if (dma_channel_get_irq0_status(dma_tx)) {
        dma_channel_acknowledge_irq0(dma_tx);
        DEV_Digital_Write(LCD_CS_PIN, 1);
        lv_disp_flush_ready(&disp_drv);     
    }
}

LVGL Widget Layout

In LVGL, we can create various user interfaces. The basic components of the interface are objects, also called widgets, such as buttons, labels, images, lists, charts, or text areas. In a interface, we can create multiple widgets simultaneously and set their positions, sizes, parent objects, styles, and event handlers and other basic properties.

LVGL widget initialization
- Demo location: examples/src/LVGL_example.c
- Implementation function: It primarily used for stylized widgets and layout widgets.

void Widgets_Init(void);

LVGL create tile
- Demo location: examples/src/LVGL_example.c
- Implementation function: A Tile view is a container object whose elements, called tiles, can be arranged in a grid format. Users can navigate between tiles by swiping. Call lv_tileview_add_tile(tileview, row_id, col_id, dir) to create a new tile at row_id row and col_id column. dir can be LV_DIR_LEFT/RIGHT/TOP/BOTTOM/HOR/VER/ALL or a value to move to the adjacent tile in the given direction by sliding.

//Create a tile at (0,0) with support for sliding down to (0,1)
tile1 = lv_tileview_add_tile(tv, 0, 0, LV_DIR_BOTTOM);

LVGL create widget
- Demo location: examples/src/LVGL_example.c
- Implementation function: To create a widget, different widgets need to use different function interfaces, you can choose the parent object to create it.

//Create a widget where tab1 is the parent object of the key, which can be replaced with a widget such as list, title, etc. that can have child objects
sw = lv_switch_create(tab1);

Alignment positioning of LVGL widget
- Demo location: examples/src/LVGL_example.c
- Implementation function: Enable a widget to be offset and positioned based on a reference point. The widget aligns to the center of the offset reference point widget.
- Alignment standard: The LVGL library supports both internal and external alignments. By default, the upper-left corner is the origin, the leftward as the positive horizontal direction, and the downward as the positive vertical direction.

//Position the btn widget 45 pixels to the left from the center point
lv_obj_align(sw, LV_ALIGN_CENTER, -45, 0);

LVGL widget to adjust font size
- Demo location: examples/inc/lv_conf.h and examples/src/LVGL_example.c
- Implementation function: In actual use, an interface may need to use multiple font sizes. Multiple font sizes can be enabled in lv_conf.h and the default font size can be set. When setting the font size, it is necessary to stylize the widget so that it can be rendered according to the set style. The lv_obj_add_style function can be used to render various parts of the widget in different states.

#define LV_FONT_MONTSERRAT_16 1                                // Enable font 16
#define LV_FONT_MONTSERRAT_18 1                                // Enable font 18
#define LV_FONT_DEFAULT &lv_font_montserrat_18                 // Set the default font size as 18

static lv_style_t style_label;                   
lv_style_init(&style_label);                                   // Initialize style
lv_style_set_text_font(&style_label, &lv_font_montserrat_16);  // Set the font size as 16
lv_obj_add_style(label,&style_label,0);                        // Set label theme style

LVGL widget event handling
- Demo location: examples/src/LVGL_example.c
- Implementation function: In LVGL, you can add an event handler callback function to a widget so that when the widget is clicked, scrolled, redrawn, etc., it triggers an event and enters the event handler callback function. Call lv_obj_add_event_cb(obj, event_cb, filter, user_data) function in the program to add the event filter handling function event_cb for the widget obj, when the widget obj triggers the filter event, the system will automatically call the event_cb function. The last parameter is a pointer to any custom data available in the event.

//Add handler function sw_event_cb for event LV_EVENT_VALUE_CHANGED to widget sw
lv_obj_add_event_cb(sw, sw_event_cb,LV_EVENT_VALUE_CHANGED,NULL);

Python

Example Demonstration

The effect displayed in this example is to show an image through LVGL.

Demo Introduction

This demo is for testing LVGL widget interaction, style design and so on. The version used is 9.1. As the development document of LVGL V9 does not provide Python example, you can refer to LVGL LVGL development documentation.

Implement Function

The example system clock is 230MHz. The peripheral clock frequency for SPI is set to match the system clock, and the LVGL library's dual buffer mechanism is utilized. Data transfer occurs in one buffer while the other buffer is rendering, ensuring smooth animation.
This example displays an image through LVGL, demonstrating the simple use of LVGL widget.

Compile and Run

Operation steps
Before starting to use, it is necessary to set up an integrated development environment Thonny Python IDE (Windows version V3.3.3)
- Download the demo, and press the onboard boot key, connect the board to the USB interface of the PC through a Micro USB cable. And then release the key, the PC will identify the pico as a removable driver. Finally, you need to copy the compiled file in .uf2 format to Pico.
- Open Thonny, upload the examples and lib directories to the development board
- Open the LCD_1in14_LVGL_test.py file under the examples directory, please refer to the steps below to run the demo
Firmware building
- Envitonment building: only test on Ubuntu 22.04
- Github: lv_micropython
- Refer to Raspberry Pi Pico port to compile
- Firmware generation path: lv_micropython/ports/rp2/build-PICO/firmware.uf2

Source Code Analysis

Source Code Structure

For LVGL library source code, you can refer to lv_micropython
The related setting of the LVGL library is at lv_micropython/lib/lv_bindings/lv_conf.h file folder, which sets the refreshing frequency of the display, system occupied data and so on.
The application code for the LVGL library is located in examples/src/LVGL_example.c and lib/LVGL.py folders of the project folder.

LVGL Initialization

Before using LVGL image library, you need to import the LVGL library and initialize the LVGL objects

Import an LVGL library
- Demo location: lib/LVGL.py
- Implementation function: Import LVGL library and use alias "lv" to facilitate calling its functions

import lvgl as lv

Create an LVGL object
- Demo location: examples/LCD_1in14_LVGL_test.py
- Implementation function: Create an LVGL object and pass in LCD and TSC objects as parameters

# Init LVGL
LVGL(LCD=LCD,TSC=TSC)

LVGL initialization
- Demo location: lib/LVGL.py
- Code description: LVGL core initializes the initialization function located in the LVGL class, which is automatically called when the LVGL object is created

if not lv.is_initialized(): lv.init()

LVGL Run

The LVGL library periodically calls the heartbeat interface function lv.tick_inc to inform LVGL of the past time so that LVGL can update its internal time state to handle time-related tasks such as animations, timers, and so on. In addition, the lv.task_handler function needs to be called so that LVGL can handle events and tasks in time to ensure that the user interface responds and refreshes.

LVGL Running interface
- Demo location: lib/LVGL.py
- Implementation method: Create an event_loop object. In the initialization function of this class, we create a timer. The timer will automatically call the heartbeat interface function and event handler function within a set time interval. The time interval for the call can be adjusted by passing the freq parameter, such as lv_utils.event_loop(freq=200), which defaults to 40 ms.

# Create event loop if not yet present
if not lv_utils.event_loop.is_running(): self.event_loop=lv_utils.event_loop()

LVGL heartbeat interface
- Demo location: lib/lv_utils.py
- Implementation method: You need to make sure that the priority of lv.task_handler is lower than that of lv.tick_inc , so in this case, lv.tick_inc is called in the timer callback function.

#Timer callback function called every 5ms
self.timer.init(mode=Timer.PERIODIC, period=self.delay, callback=self.timer_cb) // In this case, self.delay = 5

def timer_cb(self, t):
    lv.tick_inc(self.delay)
    if self.scheduled < self.max_scheduled:
        try:
            micropython.schedule(self.task_handler_ref, 0)
            self.scheduled += 1 # The number of tasks being processed has increased
        except:
            pass

LVGL Task Processor
- Demo location: lib/lv_utils.py
- Implementation method: To handle LVGL tasks, you need to call lv.task_handler at regular intervals, in this case after calling lv.tick_inc in the timer callback function.

def task_handler(self, _):
    try:
        if lv._nesting.value == 0:
            lv.task_handler()
            if self.refresh_cb: self.refresh_cb()
        self.scheduled -= 1 # The number of tasks being processed has decreased
    except Exception as e:
        if self.exception_sink:
            self.exception_sink(e)

LVGL Display

To implement LVGL display, you must initialize a display driver and set the various properties of the display driver, such as color format, draw buffer, rendering mode, and display callback function. At each LV_DEF_REFR_PERIOD (set in lv_conf.h), LVGL detects if something has happened on the UI that needs to be redrawn. For example, a button is pressed, a chart is changed, an animation occurs, etc. When redrawing is needed, LVGL calls the display callback function to complete the drawing of the image in the refresh area.

LVGL display refreshing rate
- Demo location: lv_micropython/lib/lv_bindings/lv_conf.h
- Setting method: In lv_conf.h, you can modify LV_DEF_REFR_PERIOD to change the refresh time of the screen.

#define LV_DEF_REFR_PERIOD 10 // Unit: ms, here is 10ms

LVGL display related variable definition
- Demo location: lib/LVGL.py
- Implementation function: The sizes of buf0 and buf1 are set to 33% of the screen display area to implement the LVGL dual buffer mechanism, which reduces the appearance of jagged edges during large area refresh of screen updates while effectively increasing the screen refresh rate; when using a single buffer, it is best to set it to 10% of the screen display area, which can effectively reduce system usage but may result in noticeable jagged edges during large area refresh of image.

# Init LVGL display
buf1 = lv.draw_buf_create(self.LCD.width, self.LCD.height // 3 , color_format, 0)
buf2 = lv.draw_buf_create(self.LCD.width, self.LCD.height // 3, color_format, 0)

LVGL display device registration
- Demo location: lib/LVGL.py
- Implementation function: According to the design requirements, improve the core structure variables of the LVGL library, initialize the display driver disp_drv, and set the drawing buffer, which is a simple array used by LVGL to render screen content. Once the rendering is ready, the content of the draw buffer will be sent to the display using the disp_drv_flush_cb function set in the display driver.

self.disp_drv = lv.display_create(self.LCD.width, self.LCD.height) # Create a display driver object and set the width and height
self.disp_drv.set_color_format(color_format) # Set color format to RGB565
self.disp_drv.set_draw_buffers(buf1, buf2)   # Set the drawing buffer
self.disp_drv.set_render_mode(lv.DISPLAY_RENDER_MODE.PARTIAL) # Set the rendering mode to partial refresh mode
self.disp_drv.set_flush_cb(self.disp_drv_flush_cb) # Set display callback function

LVGL display callback function
- Demo location: lib/LVGL.py
- Implementation function: Mainly complete the drawing of the image in the refresh area.

def disp_drv_flush_cb(self,disp_drv,area,color_p)
Parameters:
    disp_drv : Displays driver structure pointers, which contain information about the display and function pointers. This parameter is often used to notify you that a refresh is complete
    area     : Region structure pointer, containing the position information of the area to be refreshed. In this demo, you can use it for creating TFT display window.
    color_p     : Color structure pointer, indicating the color data to be displayed in the refresh area. In this demo, it reads the address as DMA input to transmit data to the SPI bus and completes the image drawing

LVGL display callback function implementation
- Demo location: lib/LVGL.py
- Implementation method: In this example, to maximize the reduction of processor utilization, DMA is used for color data transmission. color_p is set as the read address, and the SPI bus output data register is set as the write address. The code is long and only shows part of it, please download the demo to view the full code.

def disp_drv_flush_cb(self,disp_drv,area,color_p):
    ......
    self.rgb565_swap_func(data_view, size)  # Convert color format
    
    self.LCD.setWindows(area.x1, area.y1, area.x2+1, area.y2+1) # Set LVGL interface display position
    
    ...... # DMA configuration is executed immediately

    while self.dma.active(): # Wait for DMA to be idle
            pass
           
    self.disp_drv.flush_ready() # Notify LVGL that data transfer is complete

LVGL Widget Layout

In LVGL, we can create various user interfaces. The basic components of the interface are objects, also called widgets, such as buttons, labels, images, lists, charts, or text areas. In a interface, we can create multiple widgets simultaneously and set their positions, sizes, parent objects, styles, and event handlers and other basic properties.

Create an LVGL interface object
- Demo location: examples/LVGL_example.py
- Implementation function: Create an LVGL interface object and pass in LCD object as parameter

# Init WIDGETS
WIDGETS(LCD=LCD)

LVGL create tile
- Demo location: examples/LVGL_example.py
- Implementation function: A Tile view is a container object whose elements, called tiles, can be arranged in a grid format. Users can navigate between tiles by swiping. Use the Tile view object to call add_tile(tileview, row_id, col_id, dir) to create a new tile on the row_id row and col_id column. dir can be lv.DIR.LEFT/RIGHT/TOP/BOTTOM/HOR/VER/ALL or a value to move to the adjacent tile in the given direction by sliding.

//Create a tile at (0,0) with support for sliding down to (0,1)
self.tv = lv.tileview(self.scr)
self.tile1 = self.tv.add_tile(0, 0, lv.DIR.BOTTOM)

LVGL create widget
- Demo location: examples/LVGL_example.py
- Implementation function: To create a widget, different widgets need to use different function interfaces, you can choose the parent object to create it.

//Create a table widget where tile2 is the parent object of the widget, which can be replaced with a widget such as list, title, etc. that can have child objects
self.table_imu_data = lv.table(self.tile2)

Alignment positioning of LVGL widget
- Demo location: examples/LVGL_example.py
- Implementation function: Enable a widget to be offset and positioned based on a reference point. The widget aligns to the center of the offset reference point widget.
- Alignment standard: The LVGL library supports both internal and external alignments. By default, the upper-left corner is the origin, the leftward as the positive horizontal direction, and the downward as the positive vertical direction.

//Position the widget 15 pixels to the right from the center point
self.table_imu_data.align(lv.ALIGN.CENTER, 15 ,0)

LVGL widget to adjust font size
- Demo location: lv_micropython/lib/lv_bindings/lv_conf.h and examples/LVGL_example.py
- Implementation function: In actual use, an interface may need to use multiple font sizes. Multiple font sizes can be enabled in lv_conf.h and the default font size can be set. When setting the font size, it is necessary to stylize the widget so that it can be rendered according to the set style. The add_style function can be used to render various parts of the widget in different states.

#define LV_FONT_MONTSERRAT_16 1                                // Enable font 16
#define LV_FONT_MONTSERRAT_18 1                                // Enable font 18
#define LV_FONT_DEFAULT &lv_font_montserrat_18                 // Set the default font size as 18

table_imu_data= lv.style_t()                           // Create an object
table_imu_data.init()                                  // Initialize
table_imu_data.set_text_font(lv.font_montserrat_16)    // Set the font size as 16

self.table_imu_data.add_style(style_imu_table, 0)      // Set the style

PicoProbe Tutorial

Install OpenOCD

Linux (and Raspberry Pi)

Download the Dependency Library

sudo apt install automake autoconf build-essential texinfo libtool libftdi-dev libusb-1.0-0-dev

Get and Compile

git clone https://github.com/raspberrypi/openocd.git
cd openocd
./bootstrap
./configure
make -j4
sudo make install

Windows

Because OpenOCD self-compilation is complicated in the Windows environment, it is recommended to use the compiled version
- Click this link to download
Unzip and store in a shorter directory, such as directly in the C drive

Add Environment Variables

Click on the Start menu and search for "Environment Variables"
Click on "Edit the System Environment Variables"
Double-click the "Path" variable to enter the editing interface
Add a new path
- ①Create a new variable address
- ②Enter the address where the OpenOCD is stored
- ③Click OK to save
Click "OK" to save your changes
Restart the computer

Install GDB

Linux (and Raspberry Pi)

Install gdb-multiarch
```
sudo apt install gdb-multiarch
```

Windows

If you have the pico-sdk environment installed correctly, skip this step, as GDB is already included in the Arm GNU Toolchain
If you do not have pico-sdk installed, it is recommended to use the official pico installer to install it
- Official download address
- Offline package

Use Raspberry Pi Debug Probe to Flash the Program

Pico Debug Probe allows you to load binary files via the SWD port and OpenOCD
Every time you push a new binary file to Pico, you do not need to unplug and then hold down the BOOTSEL button

Using RP2350 as an example, the flashing command is

sudo openocd -f interface/cmsis-dap.cfg -f target/rp2350.cfg -c "adapter speed 5000" -c "program {your elf file name}.elf verify reset exit”

If you have a file named blink.elf in your current folder

sudo openocd -f interface/cmsis-dap.cfg -f target/rp2350.cfg -c "adapter speed 5000" -c "program blink.elf verify reset exit"

Use Raspberry Pi Debug Probe to Debug the Orogram

Open the OpenOCD Server

You can use openocd in server mode and connect it to GDB, providing you with breakpoints and "correct" debugging
- Using RP2350 as an example again, enter the following Linux command
```
sudo openocd -f interface/cmsis-dap.cfg -f target/rp2350.cfg -c "adapter speed 5000"
```
- In Windows PowerShell, enter the following command
  
  Starting to listen to the 3333 interface of this machine at this time indicates that the OpenOCD server has been successfully turned on

Use the GDB Command Line

This demo is built based on the pico-sdk environment, and the pico-example is compiled

Open PowerShell and go to the corresponding build folder, here the blink demo is used as an example
Open GBD and enter the following command
- If it is Windows, the input command is
```
arm-none-eabi-gdb blink.elf
```
- If it is Linux, the input command is
```
gdb blink.elf
```
Enter the following commands in sequence
```
target remote localhost:3333
load
continue
```
After successful execution, you can see pico executing blink, the led flickers

Debug with VSCode (Advanced)

Make sure that Open the OpenOCD server and Use the GDB command line are working properly
Make sure that the Pico compilation environment is set up properly
Make sure you have the following plugins installed on your VSCode
1. Cortex-Debug
2. Cmake-tools
3. C/C++

First open the OpenOCD server
Open the pico-examples folder with VSC and start the blink demo
Use the shortcut key F1 and enter the following command
```
open 'launch.json'
```

Once opened, put the following in it

If it is Windows, then enter

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Pico Debug",
            "type":"cortex-debug",
            "cwd": "${workspaceRoot}",
            "executable": "${command:cmake.launchTargetPath}",
            "request": "launch",
            "servertype": "external",
            // This may need to be arm-none-eabi-gdb depending on your system
            "gdbPath" : "gdb",
            // Connect to an already running OpenOCD instance
            "gdbTarget": "localhost:3333",
            "svdFile": "${env:PICO_SDK_PATH}/src/rp2350/hardware_regs/rp2350.svd",
            "runToMain": true,
            // Work around for stopping at main on restart
            "postRestartCommands": [
                "break main",
                "continue"
            ]
        }
    ]
}

If it is Linux, then enter

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Pico Debug",
            "type":"cortex-debug",
            "cwd": "${workspaceRoot}",
            "executable": "${command:cmake.launchTargetPath}",
            "request": "launch",
            "servertype": "external",
            // This may need to be arm-none-eabi-gdb depending on your system
            "gdbPath" : "arm-none-eabi-gdb",
            // Connect to an already running OpenOCD instance
            "gdbTarget": "localhost:3333",
            "svdFile": "${env:PICO_SDK_PATH}/src/rp2350/hardware_regs/rp2350.svd",
            "runToMain": true,
            // Work around for stopping at main on restart
            "postRestartCommands": [
                "break main",
                "continue"
            ]
        }
    ]
}

The difference between the two is that the gdb called is different

Enter the Run & Debug interface with shortcut keys Ctrl+Shift+D
- ①Select Pico Debug as the debugger
- ②Select CMake as debug mode
- ③Start debugging button, shortcut key F5
- ④Select blink as debugging object
Click the debug button to enter the debugging mode, and the shortcut key is F5
The debugging toolbar appears
- ①Restart your device
- ②Continue to run the program
- ③Execute the next step
- ④Enter function running
- ⑤Exit function running
- ⑥Stop debugging
Click to continue running the program, using the shortcut key F5, you will see the pico running the blink program

Resources

Supporting Resources

Document

RP2350-GEEK Schematic diagram

Demo

RP2350-GEEK Demo

Official Resources

Raspberry Pi Official Documents

Raspberry Pi Open Source Demos

FAQ

Question: Raspberry Pi Pico 2 GPIO is configured as a pull-down input, why does reading IO show a high voltage level when the pin is left unconnected?

Answer:

You can refer to the RP2350-E9 section in the RP2350 Datasheet

Support

Technical Support

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