Serial adapters

The Serial voltages page explains the differences between various types of voltage levels used for serial ports, and explains which boards use which voltages. Pin layout for the MiniDIN8 connectors are described here.

Logic level serial adapters
The following sections, arranged alphabetically by vendor, show a variety of serial adapters which can be used to convert from logic level serial to RS-232 level serial.

Acroname
Acroname sells both an RS-232 and a USB adapter. Note that the RS-232 adapter will work with 5v devices (robostix), and 3.3v devices (breakout-gs and other gumstix serial). These are also available as an RS-232 bundle and a USB bundle which include the appropriate cables for connecting to your PC as well as the extension cable.

Both the RS-232 and USB adapters have pinouts which allow the devices to be connected directly into the robostix connectors, but note that pin 1 on the Acroname adapters might not be the side you expect. With headers installed on top of the Robostix board, the "top" of the adapter must face away from the board. (For right-angle headers on top of the board, the adapter looks upside-down when connected correctly.)

HVW Tech
HVWTech sells both an RS-232 and a USB adapter. Note that these are both 5v only devices. One nice feature of these adapters is that they're both designed to plug into solderless breadboards.

Microbotics
Microbotics makes a few small adapters, including a dual channel version.

Pololu
Pololu sells both an RS-232 and a USB adapter. Both of these will adapters will work at 3.3v or 5v, so can be used with the robostix or the breakout-gs.

SparkFun
Sparkfun sells an RS-232, CP2102 based USB, CP2103 based USB, and FT232RL based USB adapters. The RS-232 adapter works with 3.3v and 5v. The USB adapters are 3.3v adapters, but because they're bus powered, you can insert a 10k resistor inline with the USB Rx line and make it work with 5v. The 3.3v logic high on the USB Tx line will be seen as a logic high by most modern 5v logic.

FTDI
FTDI makes a couple of interesting USB to logic-level serial cables. Note that you can choose UK or USA pricing from here.

Build your own
This site has an incredibly simple circuit for interfacing an RS-232 circuit to logic level serial.

IOGear
IOGear makes a standard USB to RS-232 serial adapter cable, useful for Gumstix programming from laptops without legacy ports. Works perfectly with HyperTerminal in Windows. You'll have to short the RTS and CTS pins to use it with Minicom in Linux, or else it's good for Rx only!

Aten
Aten makes a USB to RS-232 converter, UC232A. I have used this successfully on both Windows XP (Aten provide drivers for windows), and Ubuntu 6.10 Linux (built-in support).