Thursday, 11 July 2013

Active-HIGH Vs Active-LOW Button



 In this post, I am going to talk about a very simple thing about button. You can connect your button normally in 2 ways when dealing with microcontroller :
  • Active-HIGH
  • Active-LOW



Active-LOW button with pull up resistor:

Active-LOW button
Active-LOW button means that when you press/close the switch, then the signal sent to the MCU will be LOW. As you can see from the above diagram, when the switch is open, the signal sent to MCU is actually HIGH, and when the switch is closed, the MCU pin will be directly connected to GND. That is why this kind of configuration is Active-LOW configuration.

Active-HIGH button with pull down resistor


Active-HIGH button

Active-HIGH button means that when you press/close the switch, then the signal sent to the MCU will be HIGH. As you can see from the above diagram, when the switch is open, the signal sent to MCU is actually LOW, and when the switch is closed, the MCU pin will be directly connected to VCC. That is why this kind of configuration is Active-HIGH configuration.

I tested the BB Prince that I get that I mention in my previous post with a very simple sketch that you can download it here :


A simple demo video:




-VK