Nokia DKU-5 and CA-42 clone cables

USB connection

Nokia DKU-5 and CA-42 clone cables are available widely, and cheaply (from US$4.00 or UK£2.50 including postage on EBay at time of writing). Instructions for identifying each pin are available at http://buffalo.nas-central.org/index.php/Use_a_Nokia_Serial_Cable_on_an_ARM9_Linkstation

FTDI sell a couple of reasonably cheap USB to 3v3 serial cables, part numbers TTL-232R-3V3 and TTL-232R-3V3-WE, which are known to work. The TTL-232R-3V3 has a 6 pin connector which can be used by swapping the pins to make it compatible with the NSLU2, while the -WE version has bare wires that you can connect up as you like. They are available from the FTDI Online Store.

Using a USB to TTL converter is nice because it seems to solve the floating RxD problem which prevents the NSLU2 from booting (see the section titled, "Serial port and picking-up mains: a word of caution" on this page). The following steps describe how to hook up the TTL-232R-3V3 6-pin connector to the NSLU2 4-pin serial port.

1. Carefully remove the female pins from the TTL-232R-3V3 6-pin connector by lifting the black tabs that hold each pin in place. A small flat-head screwdriver or a razor blade works well.
2. Connect the orange wire of the TTL-232R-3V3 to pin 2 of the NSLU2 serial port, the yellow wire to pin 3, and the black wire to pin 4. Don't connect pin 1 on theNSLU2, and the brown, green, and red wires of the TTL-232R-3V3. I reused the black 6-pin connector to hold the socket pins in place.

A USB based data cable for a mobile phone is another possibility. Most (if not all) of these cables are nothing more than an USB to serial port adapter, and as most mobile phone today are using 3.3V anyway they already have the right signal levels.

Most of the cheap cables are based on a Prolific PL2303 chipset (PL2303 datasheet ) which is supported under Windows (Driver Download) and Linux. A third party Nokia data cable for a 8000 series phone has been used with no problems. A data cables from the Siemens C25/35/45 works too. The cables from the old models (i.e. C25) costs a 2..3$.

For Nokia DKU-5 or CA-42 (WT048000317):
This cable seems easier to get in Australia (I got mine off eBay.) There are generic versions available, so the colours might be different. You will probably need a multimeter to find the correct wires.

From the USB/PC point of view:
GND: White (maybe also Yellow)
TX: Red
RX: Blue (apparently not Green)