can i use pull up resistor on pwm pins

[raman00084]

i am developing dspic board it operates at 5v level. my doubts is can i use 10k upllup resistor on pwm pins, spi pins , uart tx/rx pins and qei(A,B, INDEX). ?


regards
KALYAN

 

[barry]

I don't see why not.

 

[FvM]

Use pull-up resistors to achieve exactly what? I presume you mean pull-up to 5V. Are you using a 3.3V or 5V dsPIC?

It only makes sense for input and open drain output pins. Some of the mentioned pins are push-pull outputs, so a pull-up resistor would be useless. If you are using pull-ups to 5V with a 3.3V dsPIC, take care that the respective pins are 5V-tolerant.

 

[barry]

Use pull-up resistors to achieve exactly what? I presume you mean pull-up to 5V. Are you using a 3.3V or 5V dsPIC?

It only makes sense for input and open drain output pins. Some of the mentioned pins are push-pull outputs, so a pull-up resistor would be useless. If you are using pull-ups to 5V with a 3.3V dsPIC, take care that the respective pins are 5V-tolerant.

It would make sense if the OP is trying to maintain a high state on the output until the processor starts up, regardless of whether they're push-pull outputs or not. A lot of devices start up with the outputs tri-stated (not sure about the dspic)

 

[Pulsetronics]

When configuring mcu for PWM, the pins are always set as outputs so I didn't see any reason why you will use a Pull up resistor for an output Pin

 

[FvM]

It would make sense if the OP is trying to maintain a high state on the output until the processor starts up, regardless of whether they're push-pull outputs or not.

Yes, in case of the outputs. But this point won't be particularly related to 5V operation. In wonder if the original post is just unclear or intentionally mixes unrelated design objectives?

 

[barry]

Yes, in case of the outputs. But this point won't be particularly related to 5V operation. In wonder if the original post is just unclear or intentionally mixes unrelated design objectives?

That would never happen on the edaboard!

 

[raman00084]

Is there is any harm in using pull up on pwm pins because some projects i will use the pwm pins as io and for other project as pwm. So can i use pull up? My ds pic works on 5v supply

 

[Pulsetronics]

You can use PWM for either inPut and Output when not configured for PWM.