Creating Kindle Serial Adapter

Hi all,

I am trying to re-use an old serial-USB cable I have lying around to interface with my KT2 Basic (which I have properly bricked, doh!)

The adapter I have is the AP1100R1 v1.2, which has a PL2303HXD chip.

The nice thing about this chip is that the VDD_325 on pin 4 supports a variable input:

Currently it looks like it is hardwired to the VO_33, or the 3.3V input (i.e. I get continuity between pins).

From the AP1100R1 datasheet, it looks like I can get GND, TXD and RXD off pins 5, 3 and 2 respectively.

I think the battle plan is:

1. Break the connection between VDD_325 and VO_33
2. Connect cable from 1.8V output of the KT2 to VDD_325 for input (check voltage across TXD/RXD and GND to ensure 1.8V)
3. Connect pins 5, 3 and 2 off the existing DB9 connection to the corresponding terminals on the KT2.

My main questions are:

• Does this sound sensible?
• What would be the best way to break VDD_325 -> VO_33?
• What would be the best way to connect to VDD_325? The pins are minuscule and I have a pretty fat soldering iron
• Why do I not get continuity between RXD on the chip and pin 2 on the cable? I would expect to see this? (same with TXD and pin 5)

I have almost no knowledge of electronics apart from what I've read on these forums, so please let me know if I have misunderstood something!

Thanks for your help,

James

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