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5 Simple Ways to Save IO Pins

It has been far too long since I have put up a new post so I thought I would share some techniques I've discovered while working with low pin count micro-controllers like the ATtiny85, LPC810 and the PIC16F1827. A lack of IO pins can be a limiting factor but there are a number of ways to get more functionality out of what is available. This post covers five useful techniques I have used in various projects. Please note that the schematics in the post are only meant to give you an idea of how the technique works - you will need to adjust component selection and values to suit your specific ap…

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The Bluebell, a Bluetooth Notification Device

After more than three weeks, numerous interruptions and delays the project I though would take a few days is finally finished. Finished enough to publish at least. This post describes the Bluebell - a small Bluetooth controlled ambient device built around an ATtiny85 CPU. This is one of the first complete projects based around my ATtiny85 template library which is a bit of a milestone for that project. The Hardware The project pulls together a number of things I've spoken about in recent posts such as the software based UART, a HC-05 Bluetooth module and RGB LEDs driven by PWM so I won't discu…

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PWM Output on the ATtiny85

The next step in the Bluebell project is a way to provide notifications. We can control the device remotely using Bluetooth and now we need to make it display the data sent to it in an easily noticeable format. I'm going to use an RGB LED for this - it can be driven through standard digital pins to give 7 different colour values but it would be nice to expand that range. Because the ATtiny doesn't have any way to control the current or voltage on an output pin we have to simulate that using PWM. What is PWM? PWM (Pulse Width Modulation) is a way of simulating different voltage levels with a si…

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Using the HC-05 Bluetooth Breakout

In my previous post I described the implementation of a two pin, interrupt driven serial interface for the ATtiny - in this post I'll describe how to configure and use a HC-05 Bluetooth breakout board with that interface so you can remotely control any ATtiny based circuit. The HC-05 Bluetooth Module These modules are widely available and usually relatively cheap (about $AU 6 on eBay). There are two common configurations available - one is a module with a pair of IO pins down each side and the other format is a breakout board with some supporting circuitry and a set of 6 pins at one end. Both…

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A Software UART for the ATtiny85

I've recently started work on a small project to provide visual notifications from a PC over a Bluetooth connection. I mentioned it on G+ a little while ago, it's essentially a minimalist version of this product. I started working on a post describing the work I was doing but it quickly expanded into something much larger than I expected as I started to describe aspects of my ATtiny85 template library which is being used as the basis of the project. I decided to split the post into a number of smaller ones so I can cover the various topics in detail without swamping you with information. This…

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