Should I use pullup or pulldown ?

Status
Not open for further replies.
M

milan.rajik

Banned
Joined
Apr 1, 2013
Messages
2,524
Helped
540
Reputation
1,078
Reaction score
524
Trophy points
1,393
Visit site
Activity points
0
I am using STM32F407VGT6 for my project. I am new to STM32. I am using it for GSM communication and I want to know whether I have to pullup or pull down UART lines. What value of resistors I have to use. 4.7k ? It operates at 3.3V.
 

If you're making a PCB, in general, always put a footprint for both. Also if I were you, I would also put a series footprint as well. If not needed, you can leave the footprints un-populated (the series one should be populated with a 0Ohm resistor). However, if you encountered noise, you could make a low-pass filter using the series footprint and one of the pull-up or pull-down footprints.

Based on Datasheet, I see the STM has both internal pull-up and pull-down. For external pull-up (or down), 4.7K would be ok in most of the cases.


Good Luck,
 
Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…