What is it?

The Double Bubble Backpack allows you to display up to EIGHT digits on a bright and easy to read, display - with only three IO pins! At only 1.25” by .5”, it is compact enough to fit in a watch yet bright enough to be clearly seen several feet away – even in a bright room. It uses the popular MAX7219 chip, which allows you to stack up to eight of these little guys together on the same SPI bus. This is a great way to display data from a microcontroller to a user.

Why did you make it?

I wanted a quick and straightforward way to add visual feedback to my projects - something that I could have up and running within 5 minutes. I knew there was a better way so I came up with the Bubble Backpack, and a simple to use yet powerful library to control these displays with a few lines of code.

What makes it special?

Hewlett-Packard developed these LED displays for its calculators and watches - designs where space and power are limited. Each digit requires only 7mW per digit yet it is luminous enough to be seen in a bright room. Partnered with the popular MAX7219 IC, interfacing with a microcontroller is a breeze and is fully Arduino compatible with libraries provided.

Features:

• Get up and running with only three lines of code
• Comes with an easy to use Library with a Quick Start Example to get you up and running in minutes
• Fully assembled and tested
• No additional components needed
• Easily control up to eight Bubble Backpacks with the same 3 IO pins
• Excellent Readability at Only 500uAs Average per Segment
• Made with love
• One line of code to control brightness
• SPI interference
• Display is easily removable

Specifications

• 0.75” by 0.9”
• Input Voltage: 4.0v – 5.5v
• Forward Current: 5mA per segment

Any questions, concerns, or custom orders? I'm Sergio, contact me at: sergioser@snet.net Cheers!

Four Digit Bubble Backpack