DigitalSignage with Raspberry Pi

DigitalSignage with Raspberry Pi

Introduction

This is an article about ** Digital Signage with Raspberry Pi **, which won the Raspberry Pi Foundation Award at ** Minna no Raspberry Pi Contest 2019 **. I made it with the aim of digitizing a paper bulletin board and replacing it easily.

Parts used

• Raspberry Pi 3 model B --HDMI cable --Liquid crystal display
• Power supply

environment

• Raspbian
• Python3

pydrive (Google Drive API)
pdf2image
PIL
tkinter

Process flow

Overview

1. Check if the "ScanPDF" folder exists in Google Drive of the linked account (if it does not exist, create a "ScanPDF" folder and remember the id of that folder)
2. Get all the PDF files under the folder with the memorized id and store them in the local temporary folder
3. Display the PDF in the temporary folder on the display
4. If there are multiple PDF files, change the PDF file to be displayed at regular intervals.
5. Repeat steps 2 to 5 thereafter

Authentication

Allow your account access to the Google Drive API and projects using Google Oauth

Main.py

gauth = GoogleAuth()
drive = GoogleDrive(gauth)
files = os.listdir('./data/')
count = len(files)
dirtxt = 'dirdata.txt'

Folder creation / search for saving

The ScanPDF folder will be created at the first link. After that, the corresponding folder will be acquired.

Main.py

if not os.path.isfile(dirtxt):
    folder = drive.CreateFile({
        'title': 'ScanPDF',
        'mimeType': 'application/vnd.google-apps.folder'
    })
    folder.Upload()
    with open(dirtxt, mode='w') as f:
        f.write(folder['id'])
        dir_id = folder['id']
else:
    with open(dirtxt) as f:
        dir_id = f.read()

PDF file acquisition

The user adds the PDF file they want to display on the signage to the ScanPDF folder. After that, when the inside of the folder is scanned, the added PDF will be displayed on the LCD.

Main.py

  def scan(self):
    global count
    404img_path = "./data/404.png "
    tmp_dir = "./tmp/"
    shutil.rmtree(tmp_dir)
    os.mkdir(tmp_dir)
    i = 1
    query = f"'{dir_id}' in parents and trashed=false"
    try:
        for file_list in drive.ListFile({'q': query, 'maxResults': 100}):
            for file in file_list:
                if file['mimeType'] == 'application/vnd.google-apps.folder':
                    pass
                else:
                    file.GetContentFile(f'./tmp/{i+1}.pdf')
                    i += 1
    except Exception as e:
        print(e)
    files = os.listdir(tmp_dir)
    count = len(files)
    if os.path.isfile(404img_path):
        os.remove(404img_path)
    if count == 0:
        shutil.copy('404.png', 404img_path)
        shutil.rmtree(tmp_dir)
        os.mkdir(tmp_dir)
    else:
        for i in range(0, count):
            shutil.copy(f'./tmp/{i+1}.pdf',
                        f'./data/{i+1}.pdf')
        files = os.listdir('./data/')

File display

Main.py

image = convert_from_path(f'./data/{cnt % (count) + 1}.pdf')
tmp = image[0].rotate(90, expand=True).resize((sw, sh))
self.img = ImageTk.PhotoImage(tmp)
self.canvas.itemconfig(self.imgArea, image=self.img)

• If there are multiple files, the displayed file will be changed every 30 seconds.
• If the file has multiple pages, only the first page will be displayed.
• If the file does not exist, the preset "404 Not Found" (figure on the right) is displayed.

Operation image

At the end

Since the Google Drive folder is used as the file storage location, you can update it even when you are out. Furthermore, it is possible for multiple people to update by setting the access authority to the folder. Since the Raspberry Pi itself takes up almost no space, the compactness depends on the thinness of the liquid crystal. We are currently introducing this system as a contact bulletin board for university laboratories, and it is working well. We do not consider security issues.

** We welcome Pururiku Tsukkomi. Come thank you**