How do i make a FTDI cable?

FTDI Cable Introduction

The USB to RS232 converter  cables provide a simple communication method between serial devices with RS232 to modern USB supported devices. FTDI cable comes with an internal mounted electronic circuit which uses FTDI FT232R chip. This FTDI chip converts USB data to serial and vice versa. In other words, this cable provides an effective and cheap solution to connect TTL serial interface to USB. 

To use this FTDI cable, we need a device driver which is available to download freely  from FTDI website. After installation of device drivers , the US232R adapter appears as a virtual COM port in device manager settings. 

Types

This USB to serial converter is available in marker in two types. One type is just a converter module and there is USB cable connected with it as shown in figure below. If you are using this module, you will have to connect an external USB cable with this device to connect with the computer.

Another type of converter is FTDI cable which contains USB to serial converter circuitry inside the connector as shown in the figure below.

The most important point to note here is that both types use the same FT232R chip. Also, the driver installation and working procedure is the same for both. Therefore, you can use any one of these modules available with you. 

How do i make a FTDI cable out of a usb?

The FTDI chip only comes in very small SMD package (SSOP28) so a word of caution that etching a board for it at home is not easy. 

Anyway, in case someone finds this documentation helpful, here it is.

FT232RL datasheet here. Don't get confused about the chapters regarding programming the chip, it comes with defaults that allow for this use perfectly.


The bottom side is simple enough that it can be fixed if it does not align properly or something else goes wrong. In my case that side got over etched and I duplicated all traces with a strand from stranded wire.

Therefore I think that you might be able to use one sided board if you place header pins another way and freeform the bottom side from wire instead.

For soldering the FT232 chip which has only 0.65mm pitch legs I used following method. First I cleaned the pads with rosin, then covered with solder, then removed the solder with solder wick. This still left the traces covered in very thin layer of solder. Then I aligned the chip with the pads and heated each leg for a short time with soldering iron. And it worked.

Vias are made drilling with 0.7mm drill bit and using a single strand from stranded wire. And as you can see on the images the wire strands can be used for fixing mistakes also if they happen, you just have to find some clever way to keep it steady until you finish soldering it in place.