Quick2Wire have launched another of their add-on boards for the Raspberry Pi. This one gives access to 4 analog inputs and 1 analog output and is designed to be used in conjunction with their interface board.
Read more about the board and buy one here (for £16.48)
Medic for Life has blogged about the double-row of holes near the GPIO that allow you to access the second I2C bus on the Raspberry Pi.
Having followed the flight via live mapping and over the IRC channel, I thought I’d share with you the write-up from the man himself. To recap, Dave Akerman launched a Raspberry Pi inside a TARDIS replica box using a high-altitude balloon on Wednesday, eventually recovering the package in rural Wiltshire.
I like a good infographic and what better reason to feature one from Element 14 to celebrate the Raspberry Pi’s first birthday!
I’ve been playing around with some stepper motors with driver boards that I bought from eBay. They have a lot of potential and I’m planning to use them on an astronomy project… but more on that later.
The motors were £1.66 each including postage. Not the fastest delivery ever but then they were from Hong Kong.
The actual boards which arrived were much nicer than those pictured on the eBay lot and were manufactured by LC Technology. Below is a picture of the actual board and the accompanying stepper motor and cable and here’s a link to the LC Tech page about the board. The stepper motors are all 5V so can be run off the Raspberry Pi’s 5V power supply pin.
I’ve built this on a breadboard connected to the GPIO using a breakout board from HobbyTronics. It’s almost identical to the Pi Cobbler but has a nifty power light and 3.3v regulator on board. Plus they’re based in the UK, which helped with the postage at the time.
The stepper motors are then connected to the boards using a supplied cable. When the motor is working, the LEDs on the control board light up (in sequence, but they’re going so fast in the video above that you can’t really tell that).
I’ve put the Python code for this experiment on GitHub. The main Motor class was taken from work done by Stephen Phillips on his blog. Here’s his original post. My code is available at https://github.com/recantha/stepper-pi
There is a main driver script – test-all-motors.sh – which fires off 4 parallel runs of the test-motor.py script with 4 different sets of 4 GPIO pins.
For those interested, I am using the following physical pins as control pins for the motors: 8,10,12,16 and 18,22,24,26 and 3,5,7,11 and 15,19,21,23. Some of these pins have alternate uses (for example serial tx and rx) but it was necessary to use them as general output pins to get the 16 pins I needed.
What’s next?
Well, at the moment the motors each drive a bit of paper, just to show the movement. However, they have a reasonable amount of torque. So, I’m hoping to use them to control, hopefully on multiple axis, a webcam and eventually an official camera module. This will form the main part of the hardware for an upcoming astronomy project. The code for this is starting to be built as a GitHub repository.
Basic example of a web interface controlling the GPIO. Read the Instructable here. This isn’t as flashy as something like BerryIO but it gives you something basic to work from if you want to provide a web GUI.
