Tweeting Morse Code with Raspberry Pi and Arduino

By -
I'm stuck at home and have seized the opportunity to prepare for a workshop that will link the Shrimp and the Raspberry Pi.

I love reusing previous projects. This one combines two bits of software that I prepared earlier :)

Twitter client meets Morse Code flasher

The core idea is simple. The project listens to what's happening on Twitter, and displays selected tweets by flashing the contents in Morse Code.

You could do this using the Pi on its own, or the Arduino on its own, but the project is easier and more reliable if you combine the strengths of both platforms.

Why the Pi?

It's possible to run a Twitter client on the Arduino but you're pushing the hardware to its limits. I've found some Arduino Internet libraries to be unstable, and your application is likely to be using most or all of the Arduino's limited program and data memory.

The Pi's memory is roughly a million times larger than the Arduino's RAM, and Internet applications are very stable. There are several Python-based twitter clients on the Raspberry Pi to chose from. In an earlier project I picked tweepy, which was easy to use and well supported.

Why the Arduino?

You could write a morse code flasher on the Raspberry Pi but

  • you'd need some extra hardware to flash an LED, and
  • you couldn't easily ensure that the Morse code timings were correct.
The difficulty with timing comes from the fact that the Pi is running a multi-tasking operating system. This means that your application can be preempted by a more urgent task at any time.

If you've just turned the LED on, it will stay on until your program gets a chance to turn it off again. There's no way to predict how soon that will be.

By contrast the Arduino has no Operating System, so timing is much easier to predict and control.

Connecting the two

It's not hard to write a Morse Code flasher for the Arduino, and I use that as one of the exercises in Life after Blink. It took me a couple of minutes to install the code on an Arduino, and a few more to get the Arduino talking to the Pi over a serial connection using py-serial.

I already had the Twitter client code from my earlier project. The project filtered the stream of tweets, printing all those with a particular hashtag. I installed the script on the PI and modified it to send its data over the serial port.

Voila! As tweets are received the Python program  sends their text over a serial link to the Arduino. Then the Arduino converts the text to Morse Code and flashes out the content using the on-board LED.

What next

There are a few more things I plan to do. 
  • replace the Arduino with a Shrimp.
  • improve buffering so the project can handle very popular hashtags
  • make the script and sketch available on GitHub
I'll tweet when I've done them; follow @rareblog if you're interested.

Please comment below if you have any questions, or have ideas about how to improve the buffering!

Comments

Post a Comment

Popular posts from this blog

Controlling a Raspberry Pi Pico remotely using PySerial

By -
Image
Update : I'm using thie code below in another project, and found that I had not correctly fixed the reported bug. The new version passes automated tests, and I am pretty sure it works OK. I have changed the name of the class to Talker  since it can both send and receive information. Apologies to all concerned for the bug! Introduction You can use a Raspberry Pi Pico as a powerful peripheral to a host - a Raspberry Pi, a Jetson Nano, a laptop or workstation. In this article you'll see how to interact with a Pico running MicroPython or CircuitPython by writing some Python code that runs on the host. The software is easy to use. It enables you to send a Python statement to the Pico and read the results. The statement can be any valid MicroPython code. Setting up the host and the Pico For this article I've used a Raspberry Pi as the host, but any computer running Windows, Linux or Mac OS will do so long as it has Python 3.5 or later installed. In particular, you can use this t
Read more

Five steps to connect Jetson Nano and Arduino

By -
Image
Yesterday's post showed how to link a micro:bit to the Jetson Nano. One of the members of the (unofficial) NVIDIA Jetson Nano group on Facebook asked about connecting an Arduino to the Jetson. Here's a simple recipe for getting data from the Arduino to the Jetson Nano. It should work on all the Jetson models, not just the Nano, but I only have Nanos to hand. On request, I've added a recipe at the end of this post which sends data from the Jetson Nano to the Arduino; it turns the default LED on the Arduino on or off. The recipe for sending data from the Arduino to the Jetson has just 5 stages: Program the Arduino. (I used the ASCIITable example). Connect the Arduino to the Jetson using a USB connector Install pyserial on the Jetson Download a three-line Python script Run the script.   Programming the Arduino I used an Arduino Uno, and checked it on a verteran Duemilanove (above), but any Arduino should work. You'll need to do this step usi
Read more

Raspberry Pi Pico project 2 - MCP3008

By -
Image
This post show you how to drive the MCP3008 8-channel ADC using a Raspberry Pi Pico. I'll start with a personally embarrassing and annoyingly relevant story. I'll also tell you about a minor 'gotcha' when using SPI on the Pico, and how you can avoid it. Finally, I've include the code and fritzing diagram I used to test the interface. First, the story. Back in 2012, when the Raspberry Pi was fresh and new, I was running a startup called Quick2Wire.  We made add-on boards for the Pi. Just before Christmas we sent out our first batch of boards to a small army of beta-testers. The beta boards didn't work. Somehow a single trace on the pcb had got deleted and one of the GPIO pins was isolated. The boards were still usable and it wasn't too hard to solder in a jumper wire to replace the missing trace, but it was very embarrassing. It wasn't just that we'd shipped boards with a defect. The really annoying thing was that I'd set up an  automated loop-bac
Read more