#### Wolfdagon

Joined Sep 6, 2014
3
I'm new to AAC and don't know much about electronics, but I have been searching for information and found this forum. I am using the controller from a cheap USB keyboard to make an auxiliary keypad for my work computer. The auxiliary keypad will have ten keys. Five of these will be F1, F3, F4, F8, and TAB. These should be no problem since all I will have to do is short the pins on the controller just as the original keyboard keys did.
The other five keys are what I am not so sure about. Each of these last five keys, when pushed, would send a series of five to eight letter and number combinations. For example, one of the keys when pressed would send the seven letters ASSYCOM. I'm not entirely sure how to accomplish this. Reading through some threads here combined with the limited knowledge that I already possessed has gave me one idea that might work.
I'm thinking that each of these keys would activate a 555 whose output would goto a decade counter. The output from this would in turn goto a transistor array which would act as a series of switches to short the required pins in sequence to send the correct combinations of characters. All of this is just theory to me though since I have never used a decade counter or transistor aray before.
Does this sound like it would work? If so, is there anything else that I would need to add? Even if it would work, is there a better way of doing this while still using the controller from the USB keyboard? Any thoughts on this are greatly appreciated.

#### MrChips

Joined Oct 2, 2009
22,878
Welcome to AAC.

As is commonly discovered, the simplest solution is to use a microcontroller.

#### Wolfdagon

Joined Sep 6, 2014
3
Thanks for the reply MrChips. Unfortunately, I know nothing about microcontrollers. A quick Google search for microcontrollers shows that most of them cost more than I want to spend on this project. There may be cheaper ones, but I have no idea what to look for.

#### MrChips

Joined Oct 2, 2009
22,878
Then you are looking at the wrong places. Microcontrollers from $1 to$2 are readily available.

#### Wolfdagon

Joined Sep 6, 2014
3
OK, I've searched some more and found some of the cheaper microcontrollers tvht you are talking about. If I am understanding what I am seeing correctly though, I would need some kind of harware to program them. I would also have to learn how to program it. This is one of the main reasons that I was trying to use the controller from an existing keyboard, I wouldn't have to program it.