Macbook 2 NAS project

My girlfriend's old macbook is sitting around the apartment, so I thought it would make a great NAS (well a better NAS than paperweight anyway). It has a 500 GB HDD, 2 GB RAM and a 2.16 Core 2 Duo processor. My initial scheme was as follows:

1 - Get NAS4Free
2 - Make a bootable flash drive, and boot NAS4Free. Test and then use the Live USB to install NAS4Free to a second flash drive.
3 - Erase primary HDD on macbook, connect to router and use as a NAS
4 - (optional) Install an iTunes server on the flash and get that working too

After the break I'll outline the fun times that I went through on my quest for a MacBook NAS.

Digital control of an SRF05

The SRF05 is an ultrasonic sensor (datasheet). Connecting it to an Arduino has been done and is a staightforward task, for example see this site: http://luckylarry.co.uk/arduino-projects/arduino-sonic-range-finder-with-srf05/. To beef up my digital logic skills a bit, and play around with some old ICs I had, I wanted to control the SRF05 using only digital logic, and display some sort of visual representation of its output with LEDs.

This task was first broken down into a simple state machine:

1. Generate a 10 us pulse to turn on the sensor
2. Clear a shift register (HC595, datasheet)
3. Count the length of the output signal of the sensor and set shift register bits appropriately
4. Latch the shift register output to light up LEDs

For a system block diagram, schematic and some results, check out the rest of this post after the break.