Drum Machine prototype – schematic

I found some time to convert my hand drawn notes into a proper Eagle Cad schematic.

PIC24 drum machine prototype

This is a project I’ve been working on for over a year but haven’t had the time to complete yet. Electronics takes second place to children…

It’s a mini drum machine modelled on classic machines like the Roland TR808. My version is digital, playing samples rather than analogue and uses a single pic24 to do the work.

Charlieplexed lighthouse version 2 PCBs have arrived

A long exposure makes it look quite funky

My version two charlieplexed lighthouse circuit PCBs (charliediscs) have arrived back from the Seeedstudio’s fab. I used the same deal as for my last boards, this time it took around 3 weeks in total.  That’s pretty good for 20USD!

My first professionally made PCBs

A stack of PCBs ready to be assembled

I thought I’d have a go at getting my PWM controller PCB made professionally.

Updated code for simple PWM LED controller

I’ve updated the code to my LED strip driver and included a few new features.

Here’s a quick demo video.
[UPDATE 7 Mar 2011] Added input/output graph plus link to download LUT calc excel file.
[UPDATE : DEC 6 2010] I’ve had some proper PCB’s made for this circuit. More info here.

Quick post about the DSO Nano

DSO Nano (Image taken from Seeedstudio.)

A friend asked me about the oscilloscope I was using in my last post, you can see it in the very poor quality video at the end of the post. So I thought I’d make a quick post to explain.  It’s called the DSO Nano, it’s sold by Seeedstudio and the short of it is that it’s a fantastic tool for a great price.  It is limited in bandwidth, and has only one channel but I love it all the same.   It has around 1MHz of analog bandwidth which is admittedly quite low – giving a useable working limit to signals of around 100KHz – but that is more than enough for audio and fine for just about everything I’ve been doing such as debugging my PWM output from my LED fader.

Simple PWM control for LED strip

I have been playing around with building a lamp for my desk using a LED strip and constant current driver that I bought from Deal Extreme a while ago combined with a PIC12f683 to provide variable brightness via Pulse Width Modulation (PWM).

The demo using a plain old green LED as the output.

[UPDATE OCT 20 2010] I’ve updated the firmware for this project to include new features. More info and firmware download here.

Eagle CAD files for lighthouse circuit

For any one that is interested I have tidied up the Eagle CAD files for my lighthouse circuit.  You can grab them here. They’re not perfect and are probably not suitable for sending to a PCB production company but they might give you a head start of making your own version.

They’re saved from Eagle CAD version 5.6.0 so you’ll need to go to thier site to get that if you don’t have the latest version.

A little bit of help with the lighthouse circuit.

I had an email from a friend who has built my lighthouse circuit but whose LEDs were lighting up in the wrong order.  This is exactly what happened to me when I built it the first time too.  But no worries!

The great thing about charlieplexing and this circuit is that it doesn’t matter which order you place the leds on your board as you can change the code to match the correct sequence for your final layout.  This means that you can layout your circuit for ease of wiring rather than having to keep the LEDs in any particular order.  As long as the circuit is correct and that you have an LED everywhere you should have one the ordering can be sorted out later.

Lighthouse schematics and files

Update: I’ve revised the schematic for this project and had a proper PCB made, see the new version here.

For anyone who is interested (Hi Richard) here are my project files for the lighthouse project.

The project is written for the PIC12f683 using SourceBoost Technologies BoostC that I use as a tool suite in  Microchip’s MPLAB.  BoostC is fairly ANSI so if you’re using another C then it wouldn’t be hard to convert.  There’s a free version of BoostC too and I think my program will fit within it’s limits.

C source code here (7kb). : Compiled hex binary here (1kb zip).

The schematic and circuit are drawn up using the free version of Cadsoft Eagle. They were created using version 4, but the latest version of Eagle is v5 which I’ve not used yet, however the circuit is fairly simple so I doubt there would be any problems.

High resolution combined print for top and bottom of circuit for toner transfer. (4800x2222px, 163Kb)

Schematic layout of circuit. Note that in the real thing I added a couple of DIP switches in the GP0 & GP1 lines just before the resistors R4 & R5 to isolate the ICSP data and clock lines when programming. (25kb)

I’ve not included the Eagle files themselves as they make use of some random parts that I’ve made in my own library.  But the circuit is not so complex that you couldn’t copy it.  If you really want them then let me know.

If you have any problems drop me a line.