Generic TM1637 GPIO Driver

Zero-dependency generic GPIO driver for the TM1637 micro controller. It is used in the 4-digit 7-segment display by AZ-Delivery (Link). Generic means that it is not dependent on a specific GPIO interface. You can choose the GPIO interface/library on your own. Also it uses no std-lib so it can be used in embedded systems. An allocator is necessary on embedded systems because extern crate alloc (core library) is used.

This driver could/should work with other displays too if they use a TM1637 micro controller with the same I2C-like serial bus protocol specified in the data sheet.

I created this library/driver for fun and to learn new things!

See this demo (gif) I made with my Raspberry Pi using regular GPIO pins:

How does this work? How do I write a driver for that thing?

This was my first time writing a (super simple basic) kind of a device driver. As of now I'm not that much experienced with micro controllers. After some time I understood how it works by looking at the data sheet. Have a look into my code too! I tried to make as many comments as possible.

How can I use it?

My driver/library is not dependent on a specific GPIO interface. You can use crates.io: wiringpi or crates.io: gpio for example. I tested both on my Raspberry Pi. My TM1637Adapter needs functions/closures as parameters. These functions are wrappers to write High/Low to the desired Pins.

There are also utility functions on top of the driver in the module fourdigit7segdis for the 4-digit 7-segment display. You can use them or write your own functions on top of the driver.

To add this driver to your project just add the crate to your Rust project.

Does this work only on Raspberry Pi?

Probably no! Although I can't test it because I don't have an Arduino or another similar device. This should work on every device where you can write a Rust program for. Since this lib uses no standard library this should work on embedded devices. If you use it let me know what things you've built!

But yes, it was only tested using regular GPIO pins on my Raspberry Pi running Rasbperry Pi OS so far.

Who Am I?

I'm Philipp :) Feel free to contribute on Github, write me an Email (phip1611@gmail.com) or message me on Twitter (https://twitter.com/phip1611)!

Special thanks

Special thanks to https://github.com/avishorp/TM1637. His driver for the Arduino platform helped me to understand how the TM1637 micro controller works. With his work and my effort I put into understanding the data sheet I could make this driver. I also learned a lot about serial data transfer and the I2C-like serial bus protocol used by the TM1637.

I don't use any of his code directly. It just gave me some inspiration.

Troubleshooting

• Data is not correctly displayed on display
  • either your device is broken (I ordered 3 and 1 of 3 were broken) or you probably have a to high frequency. Make sure the bit-delay for TM1637Adapter::new is not too short. 100µs on Raspberry Pi should be totally fine (but 1µs worked also for me)
  • check cables and GPIO-pins (clk, dio)
• Raspberry Pi / Raspberry Pi OS
  • "Permission denied"
  • make sure your user is part of the "gpio" group
  • sudo usermod -a -G gpio <your-user-name>

Trivia

• There is another library on crates.io for the TM1637: https://github.com/igelbox/tm1637-rs It uses the "embedded-hal"-crate and takes another approach. Check this out too. :)

• I don't know if "driver" is the right word for this because it is not tied to the operating system. But the display is a device and my library can talk with it .. so yes.. basically a driver, right?