Guzunty Pi – Open Source CPLD board for the Raspberry Pi

 Electronics, Input and Output, interfacing, Raspberry Pi Hardware, Review  65 Responses »
Mar 282013
 
Guzunty Pi - Open Source CPLD board for the Raspberry Pi

The Guzunty Pi board is an open source Complex Programmable Logic Device (CPLD) add-on for the Raspberry Pi. Derek Campbell is behind this project, and has clearly spent a lot of time and effort putting it all together. He describes it… “a CPLD is like several large breadboards laid out on your desk, full of every combination of logic devices you are ever going to need. It is waiting to be told what to do. It doesn’t need a host of jumper wires like a breadboard would. It can be reprogrammed again and again (even […more…]

The leaning header of Pi5a. How best to solder a header on P5?

 Input and Output, Raspberry Pi Hardware  31 Responses »
Mar 252013
 
The leaning header of Pi5a. How best to solder a header on P5?

People seem very reticent about soldering headers to their Pis. Nobody else seems to be blogging or vlogging about it.* D’you know what? I think it was a really magnificent oversight that the original Raspberry Pis shipped with the 26 pin GPIO header on. In case you didn’t know, the original plan was to leave them off, but they didn’t get deleted from the design before the factory quoted for manufacturing – and they’ve stayed on ever since. Without that happy accident, I don’t think I would have ‘gotten’ so heavily into interfacing. You see, […more…]

How to use interrupts with Python on the Raspberry Pi and RPi.GPIO – part 3

 Input and Output, interfacing, python programming, raspberry pi  220 Responses »
Mar 222013
 
How to use interrupts with Python on the Raspberry Pi and RPi.GPIO - part 3

Multiple threaded callback interrupts in Python We’ve been learning about interrupts this week because of the brand new interrupt capabilities of RPi.GPIO. We covered a simple “wait for” interrupt in part 1, threaded callback interrupt and button debouncing in part 2 and today we’re getting sophisticated with multiple threaded callbacks. “WoooooooooOOOOOOOOOOOOOOOooooooooooo”, I hear you say. ;) Well actually, we’re not doing much that’s very different from last time, except, now there’s more of it. We’ll add another button and another threaded callback function the same as the first one (but on a different GPIO port). […more…]

How to use interrupts with Python on the Raspberry Pi and RPi.GPIO – part 2

 Input and Output, interfacing, python programming, raspberry pi  110 Responses »
Mar 202013
 
How to use interrupts with Python on the Raspberry Pi and RPi.GPIO - part 2

Interrupts are an efficient way for a program to be able to respond immediately to a specific event. In the previous article I explained the basics of using interrupts in RPi.GPIO and gave an example of a simple “wait for an event” interrupt program. In this second article I will introduce “threaded callback” which opens up a lot of new possibilities. Threaded callback – what the heck is that? I know it sounds complicated. And it probably is complicated in the C code it’s written in, but we’re Pythonites and we don’t have to go […more…]

How to use interrupts with Python on the Raspberry Pi and RPi.GPIO

 Input and Output, interfacing, python programming, raspberry pi  90 Responses »
Mar 172013
 
How to use interrupts with Python on the Raspberry Pi and RPi.GPIO

The latest big news in the world of Raspberry Pi Python GPIO programming is that Ben Croston has released an update for RPi.GPIO. Why is that a big deal? Because this version has interrupts. “What’s an interrupt?” I hear you say. It’s a way of waiting for something to happen without checking constantly whether or not it’s happening. Imagine that you’re waiting for a delivery – something you’re really excited about – like a Pi camera.You spend far too much time looking down the street in eager anticipation of the postman’s arrival. You can’t fully […more…]

How to make your own Raspberry Pi flag-waving demo

 Electronics, Input and Output, interfacing, Raspberry Pi Hardware  36 Responses »
Mar 112013
 
How to make your own Raspberry Pi flag-waving demo

After the recent call for items for the demo table over at Raspberry Pi HQ, I thought I’d send over a flag-waving set. It’s not a product for sale, but it’s one of the most eye-catching and memorable Raspberry Pi demos I’ve made. People mention it more than any of the others when I don’t take it along to Jams. There’s a video, at the end of the page, showing three Pis all waving flags together (based on three different drive systems). Making the flag So I set about making a flag. It’s pretty easy. […more…]

Controlled shutdown duration test of Pi model A with 2 cell lipo

 Electronics, Input and Output, interfacing, python programming, raspberry pi, Raspberry Pi Hardware  126 Responses »
Mar 052013
 
Controlled shutdown duration test of Pi model A with 2 cell lipo

Lithium polymer batteries are light and powerful, but they can’t be run completely flat or they are ruined. I’ve been using them for several years to fly model planes, so I have plenty of them around. I’ve also been using them at Raspberry Jam meetings to power some of my Pi demos. I thought it would be fun to make a circuit so the Pi could monitor its own battery voltage. I used an analog to digital converter (mcp3002) and had the Pi check the battery voltage every minute and shut down when the battery […more…]

Using a Wii controller with your Raspberry Pi, Gertboard, Bluetooth and Python

 Electronics, Gertboard, Input and Output, interfacing, python programming, Raspberry Pi Hardware  37 Responses »
Feb 122013
 
Using a Wii controller with your Raspberry Pi, Gertboard, Bluetooth and Python

Matt Hawkins from Raspberry Pi Spy has done the leg-work enabling Pi users to use a Wii controller – along with a Bluetooth USB dongle to send inputs to the Raspberry Pi. It uses a Python library called “CWiid” (I imagine this is pronounced “seaweed”). This is awesome because the Wii controller has 11 different digital inputs. When you consider combinations of inputs, that gives you a lot of extra possible “input commands” to play with. Theoretically*, with 11 buttons, there are 55 different 2-button combinations (11C2). That should be enough for most uses. If […more…]

fantastic sounding raspberry pi solenoid sequencer

 Electronics, Input and Output, interfacing, python programming, Raspberry Pi Hardware  4 Responses »
Jan 302013
 
fantastic sounding raspberry pi solenoid sequencer

I went along to the Oxford Raspberry Jam last night at RS HQ. There were several impressive demos. But this one was definitely the best sounding of the lot. Peter Andrew has put together a solenoid sequencer (a bit like a drum machine) which is driven by a python script on a raspberry pi. He’s also written an android app to program the beat with his Nexus 7 tablet. Solenoids are pulsed to make them strike a tin can, a jar lid, a small glass jar and a saucepan lid. The saucepan lid sounds wonderful. […more…]

How to make a RasPi into a NoSPi

 Electronics, Input and Output, interfacing, Raspberry Pi Hardware  8 Responses »
Jan 282013
 
How to make a RasPi into a NoSPi

I’ve been doing some prototyping of a new Pi related hardware project I’m working on. I’m not ready to let on what it is yet, but it involves a potentiometer. The pot in question is one of those that you need a small screwdriver to turn. So here’s what happened. I left the screwdriver standing in the pot like this… …and it fell, shorting something out. Not sure exactly what, but it may have bounced on a pin carrying 12V for a motor. What I do know for sure is that an ic chip that […more…]

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