0

12KBPS simple audio data transfer for AVR

NewImage

Thanks to Jari for sending in this great blog tip! Check it out here.

I needed a way to transfer data to AVR

This blog post is about my adventures in implementing a stupidly simple way of transferring data over audio to AVR (and why not other embedded chips too), reaching speeds up to 12kbps with really tiny code and memory footprint, using the internal oscillator of Tiny AVR, with hardware parts that cost next to nothing.

How it started

Once I got an idea of a wearable message badge made out from Tiny 8-pin AVR chip and an LCD-screen (you can buy one NOW: TagsuTag@IndieGoGo), I wanted to make it really easy to update the contents of it, from any device you usually carry with you (not just your laptop/desktop-computer).

Some constraints of course are set up by the Flash size (8192 bytes) and the RAM size (512 bytes) of the Attiny85 chip.

I spent hours pondering about different transfer methods USB, UART, Bluetooth and so on, but all of those had downsides:

  • USB: Needs 2 pins, Firmware takes 1/4th of the Flash space.
  • UART: Modern computers lack serial port and you have to have an USB adapter.
  • Bluetooth: All that pairing, price and code size… argh!
  • WiFi: Too expensive and complicated for a small device like this.

And on top of that, USB and UART are either simply missing or at least very hard to get to your phone or tablet.

I even made some tests in the spirit of those Timex watches and screen blinking, but that was painfully slow.

I then spent few minutes to think what kind of common output devices exist in cell phones, tablets, laptops and desktops and soon realized they all can play audio! Good old memories with Commodore 64 and Datassette came flowing back. I needed to try that.

Read more.


Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.

Join 14,000+ makers on Adafruit’s Discord channels and be part of the community! http://adafru.it/discord

CircuitPython 2019!

Have an amazing project to share? The Electronics Show and Tell is every Wednesday at 7:30pm ET! To join, head over to YouTube and check out the show’s live chat – we’ll post the link there.

Join us every Wednesday night at 8pm ET for Ask an Engineer!

Follow Adafruit on Instagram for top secret new products, behinds the scenes and more https://www.instagram.com/adafruit/


Maker Business — Robotics manufacturer Anki is stripped for parts

Wearables — Form a flame

Electronics — Lead-free Soldering Temperature

Biohacking — Vitamin-C + Gelatin for Accelerated Recovery

Python for Microcontrollers — See you at Supercon, Python #2 language on GitHub and more! #Python #Adafruit #CircuitPython #PythonHardware @circuitpython @micropython @ThePSF @Adafruit

Adafruit IoT Monthly — Helping Harry's Heart, CircuitPython meets AWS IoT and more!

Microsoft MakeCode — Lenticular Art Display with Crickit

Get the only spam-free daily newsletter about wearables, running a "maker business", electronic tips and more! Subscribe at AdafruitDaily.com !



No Comments

No comments yet.

Sorry, the comment form is closed at this time.