Aaron Parecki

Project Description

A lot of information about this device online is misleading. When I first heard about this, the site I was reading claimed the transmitter didn't have a battery, and used the energy from the foot impact to power the burst transmission of the device's ID. This is what got me excited about the device in the first place: that it was so simple.

I just got a Nike+iPod gadget thingy. It's pretty cool, and stores all the running stats in xml files on the iPod, making for easy hacking of the running data. However, that's not what I really want to do with it.

Using VMware Fusion and Multiple IEs, I set up my iMac to run the four major browsers simultaneously! IE 7, IE6, Firefox and Safari. With a 1920x1200 display, I can get all four to fit on the screen at once.

Haven't posted on this project in a while, but there have been some developments.

I bought a new 24" iMac last week, and it arrived on Friday. It worked flawlessly for the first day, but on Saturday, I noticed a pixel at the top of the screen about in the middle that was stuck magenta.

I was scratching my head on this one for several hours before finally figuring out the solution which turned out to be ridiculously simple.

Thank you Brandon K! You just saved me 6 hours apparently:

Just as I had suspected, the new 16mhz crystals work great.

Disclaimer: The posts in this "Ultrasonic Sensors" category are primarily a reference for myself during this project. However, I suspect some of the things I discover will be of use to others doing similar projects, so I will make them public.

Update:

We just got caller ID at my house. One of my roommates doesn't have a cell phone, so eventually everyone else stopped answering the house phone because it was always for him. But then he would come home and not know who called. Now of course, caller ID solves this problem by logging who called on the phone handset, but being me, that is not enough!

Ok, so I wasted about 3 hours on this, and have only sort of found a solution. I have a PHP script which is going to be running 24/7 checking a message queue and then interacting with a database when a message is received. It was mostly working, until it sat there for a day and I tried to use it the next day. The PHP script had quit, with the error "MySQL server has gone away." I figured there must be some sort of time limit that the mysql server will keep an idle connection alive. I couldn't find it, but luckily I was talking to nick, and he did! He found this blog entry. So I changed the my.cnf file to set the timeout to one week:

I had a thought of using a RAM disk as a message queue for a messaging application I am working on, as opposed to creating a table in a database, or using a regular flat text file. Every time I need a message to be sent, I'll add a text file on the RAM disk, then the sending process can scan for files. All of this is happening in RAM, so it won't be thrashing the disk!

This has happened once before. One day, photoshop decides it doesn't want to start up. During the loading screen, it just stops on "Reading text global resources."

One of my servers has a nasty habit of not reloading the firewall rules when it boots up. Iptables starts up just fine, but doing iptables-save shows that there are no rules listed. The weird part is that on all my other servers, I never had to do anything special to get it to remember the rules on restart.

Apparently raid arrays don't like it when you kill power to the machine. We've been doing remodeling in the house, and I've been turning on and off breakers. Apparently I forgot which breaker the servers were on, and turned it off accidentally a few times.

I recently discovered an excellent tutorial on setting up Postfix and Courier to use virtual users read from a MySQL database. This caught my attention because it is a much better setup than having real system users for all email addresses, as it allows much more flexibility. I finally set aside some time to set up a real mail server.

I was working on a website today, and I stumbled into a problem of needing to compute the brightness of a color, so that if it is a background color, I know whether to show white text or black text. My first thought was to simply add up the RGB components of the color and use that value. It turns out that is completely wrong, since pure green looks much brighter than pure blue:

I spent about an hour bashing my head against a wall with this one.