Instructables

Step 4: Wiring it up

Many Arduinos like the Anarduino, RBBB and Boarduino have a USB connector with six pins configured as Gnd, Gnd, 5V, Tx, Rx, DTR. So I decided to make a six pin female to six pin female adapter cable to go between my adapter and my Arduinos.

TIP: I have a USB BUB and use it on Anarduinos and RBBBs. They look quite differently and it is easy to put the USB BUB on opposite from what it should be. I have done this several times. I’ve been lucky that I haven’t had any apparent damage. To help prevent this I borrowed some nail polish and painted the DTR side red on both the USB BUB and the Arduinos. Now I just have to match the reds so that I don't put it on reversed. See picture.

Notice that for the six pin female header in the picture, I cut a little notch out of one pin. This is so it will fit better on the DTR pin which is sticking up a little bit. This will also identify which of the headers goes onto the adapter since they’re both six pin. I also plan to borrow a different color nail polish for this DTR pin. (see picture)


Rules:
NC means no connection
Like pins connect to each other, e.g. Tx to Tx
My adapter header has the notch for the DTR pin .


Decisions: If you decided not to use DTR then you connect the following:

Adapter         Arduino
NC                  NC
NC                  Rx
Gnd                Tx
Rx                   5V
Tx                    NC
5V                   Gnd
Just four wires. If you don’t need 5V from USB to power the Arduino, then skip the 5V also.

If you have DTR wired up then connect the following:

Adapter         Arduino
DTR                DTR
NC                  Rx
Gnd                Tx
Rx                   5V
Tx                    NC
5V                   Gnd


 *********WARNING*********************************
The Anarduino has a ground connected to two pins of the serial male header strip. Apparently, so does the Boarduino. If you are using one of these, then the following cable won’t work and can easily damage the USB adapter chip. I modified my Anarduinos so that this will work. The RBBBs are okay.
*********WARNING*********************************

Now, my cable will be a little different as I have RBBBs and I modified all of my Anarduinos so that they can accept 3.3V on the second ‘Ground’ pin. This is a jumper option of the USB BUB. Since most of my sketches use 3.3V to set Aref, I will wire it up in my cable.

Caution: If you do use this 3.3V be careful as it isn’t clear (to me anyway) how much current the chip can supply. The PL2303HX has a 5V to 3.3V converter in it, but this 3.3V is also the main power supply for the rest of the PL2303HX. In my designs, I use 3.3 for Aref. It is drawing less than 0.1 mA so shouldn’t be a problem.

Adapter         Arduino
DTR                DTR
3.3V                Rx
Gnd                Tx
Rx                   5V
Tx                    3.3V
5V                   Gnd

 For this cable, I made the wires 5” long. Note that I used heavy wire for the Ground and 5V and used wire wrap wire for the other signals. The 5V and Ground will need to carry a little more current. Plus this adds a little strength to the cable. I wrapped some electrical tape on both headers as additional strain relief.

My adapter works great!

One of the advantages of using a cable is that you can make several different ones. You might want a short one or in my case, I might want one without the 3.3V. If you make several, you might want to label them.

 
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