售后常见问题

Please refer to this post:

 https://forum.elecrow.com/discussion/726/compilation-error-demos-lv-demos-h-no-such-file-or-directory/p1?new=1

To read analog value, you need an ADC pin, but there is no available ADC pin. However, if you don't need to use a speaker, you can use GPIO17 pin as ADC input pin to read analog value.

Use the following code:

void setup()

    {

    setMode(A_pin, INPUT);

    }

    void loop()

    {

    int A_value = 0;

    A_value = digitalRead(A_Pin);

    Serial.println(A_value);

    delay(1000);

    }

Create Keyboard Interface: Use LVGL to create a virtual keyboard interface through which the user can enter values.

Read key input: Write code to detect key events and get the value entered by the user.

Assign Variables: Assign the values read from the keyboard to variables in the Arduino code.

Process input: Process these input values as needed, such as storing, displaying, or sending to other devices.

The ESP32 Display works with the home assistant. If you want to use it to display information such as temperature and humidity, you need to connect additional sensors to detect the data.

Is it possible to integrate it directly into my home assistant and use it to display temperatures and show buttons on the screen.

What I'm trying to say is, can I integrate it in as is or is it necessary to buy other hardware and use it as a monitor only?

You can use the fswebcam app to capture photos with the built-in webcam with a resolution upto VGA (640x480). For detailed usage, consult the Man Page (man fswebcam). Or the Raspberry Pi official documentation.

A quick example of taking a photo:

1) Open a new Terminal window (Ctrl+Alt+t).

2) Type the following command:

fswebcam -r 640x480 Photo1.jpg

3) Post in front of the camera, when ready to take a photo, press Enter.

4) The new photo should be saved as Photo1.jpg in your home directory.

For additional explanation, you can view this short Youtube video.

Problem:

· On the quick example above in step 2, the output file 'Photo1.jpg' will be over written without prompting each time when a picture is taken.

Solution:

You can write a Bash script which takes a picture with the webcam and save it with a filename based on the current time. The example script below saves the images in the /home/pi/webcam directory, so create the webcam subdirectory first with:

mkdir /home/pi/webcam

To create a script named webcam.sh, open up your editor of choice and write (or copy & paste) the following example code:

#!/bin/bash

DATE=$(date +"%Y-%m-%d_%H%M%S")

fswebcam -r 640x480 --no-banner /home/pi/webcam/$DATE.jpg

This script will take a picture and name the image file with a timestamp. Say we saved the script as webcam.sh, we would first make the file executable:

chmod +x webcam.sh

Then run with:

./webcam.sh

Which would run the commands in the file and give the usual output:

--- Opening /dev/video0...

Trying source module v4l2...

/dev/video0 opened.

No input was specified, using the first.

--- Capturing frame...

Corrupt JPEG data: 2 extraneous bytes before marker 0xd6

Captured frame in 0.00 seconds.

--- Processing captured image...

Disabling banner.

Writing JPEG image to '/home/pi/webcam/2022-06-21_143826.jpg'.

You can find all built-in project code in this directory:

usr/share/code/project/

They are located in the following directories:

English version

/usr/share/.user/course/

Chinese (Simplified) version

/usr/share/.user/course/zh/

There are 3 major versions of the Scratch app, each uses a different method to adjust the font size as listed below:

Scratch 1.4

1. Press Ctrl+Alt+T, a new Terminal window appears.

2. At the command prompt, type nano ~/.scratch.ini and press Enter.

3. Add the line, fontscale=1.3 (Try experiment with different values as desired).

4. Press Ctrl+X, Y to save the changes and exit the nano text editor.

Scratch 2.0

1. In the Scratch Desktop, hold-down Shift and click on the Globe icon.

2. Click on set font size and choose your desired font size (ex. 13). Note: This set the font size of the Block Palette only.

Scratch 3.0

Currently, there is no known method to adjust the font size. But there is a workaround available using Pixel Doubling, see How to enable Pixel Doubling? for details.

Debain package (.deb) installation requires root permission, thus clicking the "Install" button to start the installation will result with an error,

The proper installation steps under Raspberry Pi OS (formerly known as Raspbian) are:

1) Open a new terminal windows (Ctrl+Alt+T).

2) Change the current directory to where you have downloaded the application package file (i.e. ~/Downloads):

cd ~/Downloads

3) Start the installation with root permission:

sudo dpkg -i Letscode_3.4.0-rc.3.3_armv7l.deb

4) The installation should complete as below:

5) Launch Letscode under Menu -- Education -- Letscode