RA4 Pull up Resister Value

S

Suraj143

Active Member

• Jan 14, 2009

• #1

I need to light up an LED with RA4.Whats the best value for RA4 pull up resister (currently using 1K)?The LED current limiter is 120R.

Problem is the LED lights up very dim.

 

Last edited: Jan 14, 2009

blueroomelectronics

Well-Known Member

• Jan 14, 2009

• #2

RA4 is often open collector, best works with LEDs as a pull to GND.
So 5V to 120ohm resistor to LED Anode then cathode goes to RA4
Turn the LED on by putting a zero on PORTA.4

 

S

Suraj143

Active Member

• Jan 14, 2009

• #3

Ok I'll try that. Is it good other side as well?

 

blueroomelectronics

Well-Known Member

• Jan 15, 2009

• #4

Is what good other side?

 

be80be

Well-Known Member

• Jan 16, 2009

• #5

PortB ? I bet that it is it

 

bananasiong

New Member

• Jan 17, 2009

• #6

Perhaps he is saying sourcing instead of sinking?