As promised, here is the Part 2 of the Lipo charging series.

I wanted to build a cheap USB Lipo charger and didn't like the unavailability nor the price of the Maxim's MAX1555. Searching for something better, I stumbled upon the Microchip MCP73831. It is still way too expensive in single quantities but there ain't too many options.

PCB designed (few changes from previous one), and parts ordered. Here we go:

(download)

Click here to download:

getting-those-lipo-s-charged-part-2-with-the-mcp73831-jmsznJoHItbnECkfgfcx.zip (13.7 MB)

Here you can see it when it is charging (BTW white leds totally rock). I decided to go entirely SMD (appart from the two connectors) since the chip is a SOT-23. Not too hard to solder even if the 0805 resistors are super small. Trust me because I have the worse soldering iron on earth and the biggest tip ever. The PCB was designed in Eagle and made by the excellent DorkbotPDX service by Laen (http://www.dorkbotpdx.org/wiki/pcb_order). I got three PCB's for an excellent price and actually build only two since I had only two chips. 

The board is intentionally small and has a status LED. There really isn't much more to it, it's a single purpose device and just does the job. It is proudly Open Source Hardware.

Schematic: http://cl.ly/0N2y1e1v473E1S2z0k1l

Board file: http://cl.ly/243L32140P362N1Q1C1S

A good place to buy your components is Ebay, here is a link to one chip. 

Please do send me a picture if you build one.

I have a kit to sell (everything except the MCP73831) for 10€ + shipping if you live really far away from Europe. 

I also have a fully assembled one for 15€.

But I'll still be using this one.

Longer, less technical posts will go on: http://asselinpaul.calepin.co/

Personal Projects and what you can currently see here will stay here, don't worry.

The reasons for such a move will be explained on my first post there. Make sure you bookmark it too if you think it's worth it. Thank you anyway.

Update: Part 2 is here: http://asselinpaul.posterous.com/getting-those-lipos-charged-part-2-with-the-m

Lithium Polymer batteries are awesome.

Lipo's are delicate and need constant monitoring, many chips like the MAX1555 are here to help you achieve just that. Here is a charger I designed in Eagle but haven't actually made (student == no budget). You can have the design files and can get the PCB's made for around 12$ on the internet. All of the components are Surface Mount but frankly, it's quite easy to do (even with a 10$ iron).

I'll probably have a project using the Maxim1555 pretty soon, I'll be posted here in due time. 

While you wait for that here is the schematic of the charger and a frankly pitiful Sketchup model of what it should look like when done.

Schematic: http://cl.ly/1q1a1l403p3f380I3H3Z

PCB board: http://cl.ly/1h1c19272t1A1e2S172q

(download)

Click here to download:

getting-those-lipo-s-charged-eJcafEzqIfbJhudDJulx.zip (81 KB)

(download)

Click here to download:

getting-those-lipo-s-charged-oGxzecvJlbnjgFxFjqEs.zip (157 KB)

The chip itself is a bit expensive if you ask me and is available at Sparkfun. Another chip that is interesting is the MCP73831 from Microchip (a lot cheaper). I'll try and have a look into that as soon as I can. 

About a year ago, I had an idea. I though that I could perhaps wire a small printer similar to those find in shops to print receipts and connect it to the Internet to print news and social network updates. I was thinking about using an Arduino with the Ethernet shield to do all of this. I looked online and found a project which was doing exactly that, the Microprinter. I didn't take the project any further because I didn't have enough money and I thought that it would be another useless thing. 

To my surprise, I've discovered Little Printer. It is exactly what I had in mind except it looked nice and seams to be really easy to set up (two things that I would have been unable to do). I was really pleased to see it and to see all the positive feedback it was getting on sites like The Verge. I'd really recommend you go and have a look at what it does:  -Article on The Verge

What I learned from this is that it's not about the idea. It's about whoever takes it further and believes in it. Many people had gotten this idea but very few have actually stuck with it and put some work and effort into it. 

What is really interesting is the fact that such a product could pretty easily be made as an Open Source Hardware project. Sparkfun already sells a thermal printer and you can get an Arduino Ethernet or an Nanode for less than 50€ ( a lot less for the Nanode).

(download)

Click here to download:

it-s-all-about-taking-the-idea-further-FvaJdEkJhvvdxceunApy.zip (395 KB)

http://www.flipbit.co.uk/micro-printer.html

http://tomtaylor.co.uk/projects/microprinter

(download)

Click here to download:

it-s-all-about-taking-the-idea-further-pzAJJDEtptctkHBstoHA.zip (974 KB)

Update: If anyone is interested, I have a PCB and most parts to sell. It's a one off but send me a mail at pa.asselin@gmail.com

Update 2: I forgot the code, how could I? http://pastebin.com/BRMyt9gk   also you might want a sketch to test your design (and soldering skills) so here are two test sketch (one for the keyboard and the other one for the LED's) : 

http://pastebin.com/wq5KSzgm

http://pastebin.com/Hgdkp9ZM .

(download)

Click here to download:

rfid-spoofing-EqiogIIcyridjuhhHdDr.zip (4.64 MB)

As for the project, it is an RFID Spoofer (125kHz) Arduino shield. It is mostly based on drj113's Universal RFID key but I modified it to make an Arduino Shield. I want to fully open source my design so I have posted the schematic and .brd PCB file . In Eagle, most of the parts have the appropriate value so you can follow that. If you have any question, feel free to email me. If enough people request it, I will post a Parts list but I don't think it's worth the hassle right now (but feel free to ask me). 

The shield has 5 modes:

- Enter low power (sleep) mode

 - Enter a Hex Facility ID

 - Decimal Card ID

 - Dump the facility and Card ID

- Emulate a card

The shield is basically a big keypad with a bit of a circuitry to drive the antenna (bought here: http://www.seeedstudio.com/depot/125khz-rfid-module-uart-p-171.html?cPath=144...

All the parts where bought on Ebay, because that's cheaper than paying Mouser an extraordinary fee for shipping. Be careful though, I ordered Red SMT LED and received White one's. They might actually be better but you don't always receive what you order. 

The PCB was ordered from the excellent PCB Laen service. I really recommend his PCB service, the purple PCB's look great and look really professionally. The international shipping rate is a reasonable 5$.  

I feel like I've covered everything but if you need anything. Feel free to ask me. 

Here is the PCB board file:

http://cl.ly/230g2s1Y1f2u0i3L3V2v

Here is the schematic:

http://cl.ly/161x3O430x421D1F0z2I

If you own a Razer Deathadder and use it on a Mac, you probably noticed that the sensitivity resets to the minimum each time you log in. Here is a simple solution, a script. This Applescript will do the hard work for you. If you simply want the App, I've posted it here: http://cl.ly/20191c0b0c0w373O450r

 
set trackingValue to 5

--Open and activate System Preferences
tell application "System Preferences" to activate

--Attempt to change settings using System Events
tell application "System Events"
        tell process "System Preferences"
                try
                        --Open the "Keyboard & Mouse" pane
                        click menu item "Mouse" of menu "View" of menu bar 1
                        delay 2
                        set value of slider "Tracking Speed" of window "Mouse" to trackingValue
                        --end tell
                on error theError
                        --An error occured
                        display dialog ("Sorry, an error occured while altering Keyboard and Mouse settings:" & return & theError) buttons "OK" default button "OK"
                        
                end try
                
        end tell
        
end tell

if application "System Preferences" is running then
        tell application "System Preferences" to quit
end if  

I wanted to share a very useful tip with you. Dropbox, you know the startup that has raised $250 million and has a $4 billion valuation, is a very useful platform. I use it everyday to keep some folders in sync and also to get my files at school. I have a free acount with 4gb of storage and for me that's enough. Recently, Box.net announce that during 50 days, they would give all their iOS users 50gb of free space forever (http://reviews.cnet.com/8301-19512_7-20120674-233/get-50gb-of-free-cloud-stor.... Although I got this promotion, I just find that at the moment I don't need his much space. Maybe I'll backup my whole Music library on their but other then that, I still prefer to use Dropbox. 

Folder syncing is what Dropbox does best. As a result i stuck my whole Arduino sketch folder in my Dropbox foler. 

I then simply set the Preference on the Arduino IDE to store my sketches in this folder. 

As a result, I know always have all my sketchs with me. I can start a project on my Desktop and then finish on my laptop. It's really incredibly useful to have this set up. No more searching for sketches that are on my other computer. 

If you've read down to here, thank you for visiting my blog. I only get a few views a day and I'd appreciate if you could share this blog with others (only if you think it's worthwhile). Thank you a lot.

As you may not know, I am still at school and have may tests and exams coming up this year. By reading other blogs and sites, I have noticed that some of them tend to release less content but of a greater quality.Example:http://rossum.posterous.com/

This got me thinking I decided to change a few things. 

- I will post less often on this blog in order to have more time for studies, to research and learn new programming languages and exciting things and most importantly to spend more time creating projects. This I hope will lead to less 'crapy' projects being posted here and better, higher quality posts in general. I want to create and not spend too much time documenting.

-This is my builds blog, it should not be my daily blog. For this there's Twitter. @asselinpaul

This blog will live on and I hope that these reforms will make it a more enjoyable and interesting website.  

Here are the programmer's and maker's blogs that I generally look at. Some of them are gems and some are just project logs. In no particular order:

Read the rest of this post »

This was a personal challenge, I wanted to design something similar to the Android Unlock Pattern in less than 30 minutes. At the moment, it's an ugly piece of code but it works.

The code is available here: http://pastebin.com/FvyTEEM2

(download)

Click here to download:

arduino-unlock-pattern-uhBvCpujFkIpBbvscByx.zip (31.05 MB)

What you'll need

This is what you'll need for version 0.1 :

• a Nintendo DS touchscreen
• a display (in this case an Nokia 3310/5510 display)

How it works (work in progress)

The aim was to make this in less than half an hour. At the moment, it is a very ugly piece of code. It is also not very secure. I have yet to implement a way to prevent people from guessing the code by touching everywhere on the display. There is currently a timer that sets of when you touch the first point and re-initialises the sketch if you aren't fast enough but you really, really shouldn't use this for something you want to secure properly. If I have time, I'll try and make a library for it but then again, with exams during the whole year, time is an issue.

Wiring

*DS touchscreen to Analog 1,2,3,4

*LCD to Digital 7,6,5,4,3

Possible Improvements

*make it secure, no guessing

Video

(download)

Click here to download:

arduino.m4v (12.72 MB)

Music: Otis by Jay.Z and Kanye West

This is by far the best video I've seen in a while. Very impressive stuff.