Tuesday, February 23, 2010

Understanding Keyboard wiring and Keyboard works

Understanding Keyboard wiring and Keyboard works

As this is the First day, I went to my keyboard (Damaged Keyboard) to try to understand the wiring inside it and how to get benefit from it If I decide to use it in bigger projects:
The notes that I liked:
1- The input volt in the keyboard is +5V
2- After I checked the nature of wires, I realized that there is no standard tasks for wire, for example the red wire should be for the +5V but (using my multimeter) I noticed it is not, the +5V wire was the White wire, the common wire was the Yellow wire.
3- Now we have four wires (Red, White, Yellow, Green), this remind us about the four wires in USB cables, once I solder the wires to their right places in the chip, see the signs in the chip as the following picture:

4- I turn on my pc to get the message "Keyboard error or no keyboard present" and " to continue", I tried to press F1 but my keyboard was not working.

5- By using multimeter (Checking continuity) I could track wires from the PS2 output to the wires,
and by using the information in this site: http://www.bbdsoft.com/keyboard.html, I knew that there are two wires not working properly the data wire (Red one in my keyboard) and the +5V wire, the clock wire (Green) and common wire were good.

6- The lesson that we can understand from this is that we can use the small chip of the keyboard

to receive multiple combination from keyboard or from any other sources if we care about the input and output voltage, the data output from the chip is 11 bits output we can transfer it to any meaningful output, inside the keyboard there are two layers of thin and transparent plastic with conductive lines;

We can use it in any application, may be in the near future at this blog.



  1. i want to connect the keyboard to a light boar so when i press a key a specific light bulb tuns on
    very imp. plz reply soon

  2. Keyboards send data to computers, in that way the computer understands which key is pressed. It is not voltage value it is an 11 bits of data 8 of which represent the pressed key, so if you are planning to control a light board by keyboard you have to consider adding a keyboard decoder which they are expensive, so it is better to use shift-register to control your light board.

    Please read this page to understand keyboard logic

  3. hello, i have orange, white, green and blue wires, how do i have to set them in the board?

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