Reading if Pin is High or Low?

**Melanie** · - 31st July 2005, 19:53

Each side of the switch goes to the Port pin. There is a Resistor, one end on the Port pin, the other is nailed to +5v. That's why they are called Pull-UP - they pull UP to +5v when the pin is unused. When you close the switch, it drops the pin voltage to 0v.

Spindle · - 31st July 2005, 20:26

Melanie,

I am sorry for my newby-ness (new word). I am not an Electrical Engineer just a highschool student working on a summer project.

Right now i have the center of the switch going to ground. Then the sides of the switch going through a 10k ohm resistor, then to PORTB.5 and PORTB.7 respectively. I also have a 5 volt bus. Does anything have to be connected to it? Like a jumper from PORTB.5|7 to 5 volt as well?

**mister_e** · - 31st July 2005, 20:41

A image is always welcome i guess
<img src="http://www.picbasic.co.uk/forum/attachment.php?attachmentid=388&stc=1">

OR, as Melanie suggested, remove those pull-up resistor, and add

Code:

OPTION_REG.7=0

at the top of your code. This will enable the internal pull-up.
about VB code, tags and blah blah click here

Spindle · - 31st July 2005, 21:32

Thanks you two! It works now. I cound't have done it with out yah!

Spindle · - 1st August 2005, 03:13

Ok the only problem is now if I switch it one way and then switch it to the middle the motor still goes because I guess the command is still being sent to the motor driving circuit. There is however a _break pin you can control. See attached image. Other than how its wired from the diagram mister_e posted the ground that comes off my chip goes to the switch and then to PIN 12. This drives it low and disables the H-Bridge on circuit. The problem when the switch is turned left or right for forward and reverse movement nothing happens because _break is still being driven low. I can't think how I can make it high when the switch is left or right. Maybe instead of connecting the pin to the ground, connect it to another portb pin and when its switch left make that pin high but i don't think to 5 volt supplies will work on a switch :P again I am no electrical engineer but am trying my hardest. Any help is apreciated. Please check out the picture I basically want to do that with the break switch but only when the SPDT switch is in the middle. When its to the left and right have _break go back high.