How to Make Your Own USB to Serial Adapter

The task of making your own USB to serial adapter is not an easy one. This article will break the process down enough so you can take it on yourself. 

Step 1 - Create A Benito Board

The Benito board is a designed to let people build their own processors. Typically this done by people with intermediate soldering skills. If you feel that your skills are lacking in this department, be sure to get someone to help you with this step. The first thing that needs to be done with the board is to align the processor and to tack the corners. This simply means to solder the points down so that the processor is secure and aligned. Once you have the corners done, go around the processor and continue the process.

Step 2 - Mount the Lights

Looking at your board, you should notice a green marking which is connected to the negative side of the LED. Be sure that you solder in your LEDs on the negative side. These should be bracketed in by 220-ohm resistors. When you are finished, check your work. Be sure that you haven’t accidentally created bridges between your points. If you have, simply remove the excess solder.

Step 3 - Solder the Pullup Resistor

Now we move onto the 10k pull-up resistor. We are going to use this to create our reset pin as well as the 1 uf capacitor. This in turn will help us create the 3.6 volts that we need for clear and proper communication to the USB hub. Solder the resistor into place and then solder in your 22-ohm resistors. This is going to help the D+ and the D- signals filter.

 Step 4 - Attach the Bypass Capacitor and Filter Capacitor

Once your resistors are in place. Solder both of these into place. Atmel notes a preference of a minimum of 1 uf or of 10 uf. It is all right to compromise for a spot in the middle. You can go with a 4.7- 5.3 uf.

Step 5 - Applying the Last Two Pads

The last two pads are going to be used for the 22pf capacitors. Simply solder these into place and set your 8 MHz crystal to the side, ready to be grabbed. Keep it to the side so that it doesn’t come in contact with anything. When you are ready, solder the crystal into place and be sure to clean up any of the excess solder. From here solder in your 10k resistor, the 10 pin header and the USB connector.

Step 6 - Determine the Voltage

Now you need to determine the voltage that you are going to be using. Short either the outer or the inner jumper depending on what you are going to be using it for. Now you are going to have to program the Benito board. When you plug the board into you Firmware Uploader allow the device to run its test to be sure that the board is functioning properly. If there are no errors, go to your main system in the computer and click the “refresh” button to update your board and then BAM! You are finished.