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Matt's Projects

Sometimes I make things

WordPress.com Stats Scraper

Something that has been annoying me for a while is that there is no way to download your WordPress.com stats from the website!

So I wrote a script in python to allow you to download all of your stats into a spreadsheet. Here is the guide.

Basically, you need to provide the script with an example XML Http Request (XHR) where the website is pulling stats data from the WordPress.com server. From this XHR, the script then reconstructs a new XHR to get all of the data.

Mini Project: Porting RFM69 Library from Arduino to MBED

TLDR: Here is an RFM69 OOK library for MBED.

For an upcoming project I am using the RFM69 module by HopeRF.

The RFM69HW is a transceiver module capable of operation over a wide frequency range, including the 315, 433,868 and 915MHz license-free ISM (Industry Scientific and Medical) frequency bands.

Continue reading “Mini Project: Porting RFM69 Library from Arduino to MBED”

Project: Spectrum – Final Touches/The End

Last time I showed the final frequency response of Spectrum. I guess now I need to show the finished thing!

Continue reading “Project: Spectrum – Final Touches/The End”

Project: Spectrum – Final Frequency Response

Minus a couple of tweaks, the circuit is basically finished. I just want to adjust the brightness of the LEDs and tune up the sensitivity of the comparators. I will follow with a video soon but I need to find a decent camera to capture the full effect.

Continue reading “Project: Spectrum – Final Frequency Response”

Soft Switching – Reverse engineering the LCR45

Soft switching allows a single button to be used as both an input and a power button. An example of this is the LCR45 LCR meter from Peak Electonic Design which has two buttons – on/menu and enter/off. As you can tell from the names, both buttons operate to turn the device on/off and also trigger the menu and enter functions in the interface.

This could be achieved by using both buttons only as inputs to the processor (a PIC in this case) and never turning the chip off, simply putting it into low power mode and using the ‘on’ button to wake it from this sleep. But even the best low power mode uses more power than actually turning the device off and the battery would eventually drain. So how can we achieve a multipurpose button and still use no power when turned off? To answer this I reverse engineered the LCR45 and drew out the circuit which I will now explain.

Continue reading “Soft Switching – Reverse engineering the LCR45”

Project: Spectrum – PCB V1, a bit of a disaster

With all of the sub-systems developed on a breadboard I moved to the next step of designing and ordering the circuit board that I would use for the final product. For now, I will skip over the design choices and jump straight to what happened when I received the board and what the mistakes were and how I have changed my design.

Continue reading “Project: Spectrum – PCB V1, a bit of a disaster”

Project: Spectrum – Microphone Circuit

The system needs a way to listen to the sound around it and the natural way to do this is with an electret microphone. I will probably include a 3.5mm jack input to allow you to plug music straight in too.

Continue reading “Project: Spectrum – Microphone Circuit”

Project: Spectrum – Filter Design

Frequency Response

As I said in the previous post, I want my filters to perform in the same way as the MSGEQ7. The frequency response of this chip is given in it’s datasheet.

MSGEQ7_Frequency_response.png
The 7 frequency band responses of the MSGEQ7

From the datasheet I can see that, to replicate this response, I will need 7 bandpass filters at 63Hz, 160Hz, 400Hz, 1kHz, 2.5kHz, 6.25kHz and 16kHz. Each filter will need a quality factor of 6 (this basically sets the bandwidth of the filter).

Continue reading “Project: Spectrum – Filter Design”

Project: Spectrum – Beginning

It’s getting harder and harder to find spare time to work on projects. Firstly, the holidays at MIT are tiny compared to the holidays I get at Cambridge, and now that it’s finally Summer I am doing an internship which keeps me pretty busy 5 days a week, and I still want time to explore California and surrounding areas.

Anyway, I want to do a project that looks good and has some analogue electronics in it. I will build a system that listens to sound via a microphone, breaks the sound down into frequency bands and displays how loud each frequency band is using a strip of LEDs. It’s a similar idea to a Colour Organ but I want 7 frequency bands and 10 volume levels per frequency band (a total of 70 LEDs).

Continue reading “Project: Spectrum – Beginning”

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