Charging USB/Serial Cable For Nextel Phones

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UM232R.thumbnail  “The USB Serial Cable” now you all might say what the heck how can it be USB and Serial at the same time. Well, Click on the More link to find out how. It uses this cool chip from FTDI Chip.

Ok First of all this all centers around the FT232R chip from FTDI, This chip is a transparent USB to Serial connection that requires minimal external components.

The Purpose of this cable is to allow a connection to the phone using the phone's serial port but plug it into a serial portless laptop, thus allowing GPS navigation on the laptop while keeping the phone charged as well.

This is an upgrade from the previous hack I showed and can be entirely made by the user.

The following schematic shows the SSOP-28 chip. It includes a data transfer LED. By the way R2 should be a 270 ohm resistor.

Just in case you don't want to mess around with surface mount soldering like this asks for FTDI has a DIP style Module that you can use and just solder a few wires to the board or you can even breadboard it. The Schematic for the dip module will show up shortly.
Nextel_USB Serial Cable
For those of you who want something that can interface with a microcontroller or other device more easily, there is the FT245R chip which is really cool, it is nothing more than a USB Fifo, data comes in on the usb line and you clock it out just like a Register… Want to send something back in you just put the data out and hit a write strobe. Its that simple.

For all of the solutions there are 2 driver options that are available on the PC end. One is the VCP or Virtual Com Port, and the other one is the D2xx which are DLLs that you can use to send and receive commands from any programming software where you can use DLLs. Couldn't get any better than that.

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Written by Jason Striegel

C/C++, Java, Python, Linux developer for 18 years, A-Tech enthusiast love to share some useful tech hacks.