Thermal Printer Perl Library

What

Last month, I developed a web GUI for my Raspberry Pi thermal printer. Despite extensive testing, I struggled with some fundamental tasks, such as printing text with diacritics and creating custom characters. Existing libraries were available in Python and C, but Perl options were limited and often lacked the methods I needed. This prompted me to create my own Perl library for the Adafruit thermal printer.

What I Did

I created a Perl library for the Adafruit thermal printer by thoroughly reviewing the printer's documentation and implementing methods for nearly every command mentioned. The library includes standard functionalities for altering fonts, generating barcodes, and printing images. Additionally, I added some custom features:

  • Printing Images with Gradient Effects: This feature allows you to print images with a gradient effect, enhancing visual appeal.
  • Aligning Images: If an image is narrower than the printing paper, this method adjusts its alignment.
  • Registering Custom Fonts: You can now create custom fonts from bitmap images, offering more flexibility in print design.

Notes

During testing, I discovered a few notable points:

  • Printer Buffer: The printer has a limited buffer size (exact size unknown). Sending text longer than the buffer can cause the printer to skip some text. It's essential to allow the printer time to process and print before sending additional data.
  • Print Quality: Continuous printing for more than 30 seconds can result in blurred text or images. The printer's hardware seems to struggle with prolonged use, and the thermal paper has a limited length of 40 meters.
  • Gradient Printing: Printing with gradient effects is somewhat slow. The printer's head must adjust the heat value accurately to achieve the desired effect.
  • Gray Scale Printing: The printer cannot produce gray-scale images effectively. It automatically moves to a new line after printing the first one, and I was unable to find a solution or firmware modification to address this limitation.

You can find the library here: Adafruit Thermal Printer Perl Library



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