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Written by Tarkan Akdam
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Monday, 10 September 2007 |
Mod Process:
Being an electronic engineer by profession, this mod had to be made to the highest standards. My first criteria was that it should be a total plug and play solution, no hacking or cuts bits off the iPod, and secondly it had to reflect my abilities so no glue and definitely no bits of sticky tape holding it together.
The first task was to measure up the iPod internals to determine the ideal shape and size for the adaptor, the shape was very important as I wanted to make use of internal metal frame to provide the support. This is extremely important so that in the case of a fall the adaptor would not cause any damage by hitting the motherboard or the LCD.
Several more measurements had to be taken while designing the adaptor as the PCB plus compact flash would end up being slight thicker than the standard hard drive. So the position of the Compact Flash was critical to allow the case of the iPod to be closed.
The circuit itself is pretty easy, using the manufacturer's datasheet for the hard drive and the compact flash card pin out for true IDE mode. The iPod uses 16bit DMA transfers which most modern Compact Flash cards are capable of.
Once I was satisfied, the design was sent away for fabrication. I waited with joy to the thought of having to hand solder 0.5mm and 1.27mm pitch connectors to the PCB when it arrives. I decided to have the PCB made in blue just because I like the color and I think it looks nice once installed.
The circuit board is finished with some neoprene foam strips where the board locks in to the internal metal frame of the iPod. The foam also acts as shock absorbers so that the adaptor is isolated from vibrations and heavy drops. The foam strips provide the necessary clearance between the adaptor and the motherboard / LCD assembly to protect these components from damage as well as providing the necessary space for ventilation of the heat generated by the processors.
Installation is very easy, once you have managed to open the iPod without damaging the finish. The hard drive and its associated bumpers are removed, the adaptor is slotted in. The hard drive ribbon is fed in to the ZIF connector on the adaptor and locked down, Compact Flash card is inserted and the iPod can now be closed up once the battery is reconnected.
On the first power up you will be asked to connect to your computer so that iTunes can restore the iPod. After following the prompts the iPod was restored in a couple of minutes ready for syncing.
Testing:
First thing I noticed with the compact flash version of the Video IPod was how smooth the user experience is, gone was the delays waiting for the hard drive to spin up and be read which takes anything from 2 to 4 seconds. Moving through tracks was amazing, as fast as you can tap the forward button the iPod was already trying to play the song. Fast forwarding through movies was an experience, spinning your finger around the scroll wheel the iPod started to play the video the moment your finger stopped.
I tested several compact flash cards with the adaptor varying in capacity and speed rating. While the speed rating did not have much of an impact on the user interface, it did however affect the speed which the iPod could sync with iTunes.
I would say that the new 150x UDMA Compact Flash cards should be able to match or outpace the hard drive. This chart does not include the time it takes the hard drive to spin-up before the transfer starts, which can mean the CF cards being faster in certain situations.
Transfers speeds for the various cards in KB/s
The bug bear of this version of the iPod has to be the battery life, especially during video playback. During my testing the hard drive was spun up and read every 90 seconds while playing high quality video files, and at 1.6 watts of power required to do that I expect the compact flash version to show serious increases in play time.
So I setup a comprehensive test to compare battery life between the hard drive and compact flash versions. Both hard drive and compact flash had 8 GB of identical files loaded, combination of 500 mp3's and 6 hours of high quality mp4 files. I measured how long each version stayed on continuously playing either music or video.
Video playback with the CF came in at 5hrs 49mins which is an amazing 1hrs 25mins increase over the hard drive, and if you can live with reducing the back-light a few notches I can imagine breaking the 7hr barrier.
Audio playback recorded the biggest increase in terms of actual usage time and as a percentage increase. As the back-light was off the battle was between the current draw of the storage mediums. The Compact Flash came in at 15hrs 20mins of playback and a very impressive increase of 42% equating to an extra 4hrs 30mins over the Hard Drive.
While the test results showed pretty good increases by the compact flash camp, I still think in real life usage the increases will be even more spectacular. The tests demonstrated continuous play, with no stopping / pausing / switching on and off, these increase current demand as the hard drive needs to be activated. These things are what saps power and with the compact flash installed these things do not draw anymore current than the back-light.
Video performance of the compact flash will enable you to fit in another film on a flight, on the audio front you can fit in an extra 4 hour flight.
How the Video IPod's should have performed from the factory......
Mod Specs:
· Smooth user experience (no delays waiting for the hard drive)
· Works with most Compact Flash cards (4gb to 16gb, and 32gb in the near future)
· Longer Battery life (4.5 hours increase for music play)
· Lighter (iPod weights 27g less - approximately 20% lighter)
· Drop proof (if the LCD survives, so will the Compact Flash)
iPod Compact Flash Gallery
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