Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

weak pull ups or not?

Status
Not open for further replies.

SnM

New Member
Right now I have a project that uses some swiches for controlling the microcontroller. (pic 12C508A) I supply the switch with +5 volts and a 10K resistor, and connect the other pin to the input of the microcontroller. To keep the input from floating while the switch is open, I put a 1M pull down resistor to ground. When the switch is open, the input is low, when the switch is closed the input is high. Works great.

Now, would it be better to use the weak pull-ups feature for the inputs? that way I could remove the pull-down resistors and instead of supplying the other end of the switch with +5 volts, I could tie it to ground.

What is the resistance of the weak pull up?

Do you see any problem with my logic? If I can connect my switches this way, I can save myself 1 wire (+5v).

Thanks!
 
That's what the weak pullups are for, you simply enable them and have your switches down to ground. The actual values of the pullups are given in the datasheet, but I seem to remember they are in the 200-300 KOhm range.
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top