Unused GPIO pins for TMS320F28035

Rasit GOKALAN1

Intellectual 360 points

Hello,

What should I do for unused GPIO pins?

should they be connected to GND with pull down or left unconnected?

And what will be direction of GPIO pins? Input or output?

Regards,

Raşit GÖKALAN

over 10 years ago

0 Gaston_Melo_Arg over 10 years ago

Mastermind 7675 points

left unconnected, by defaul all GPIOs are inputs.
Gastón

0 Brett Larimore over 10 years ago in reply to Gaston_Melo_Arg

TI__Guru 57255 points

Hi,

As Gaston has mentioned, all GPIO are inputs after reset. However, when using GPIO as inputs, care should be taken to make sure that the voltage on the GPIO input is either logic high or logic low. Issues can occur if a mid-level voltage is on an input pin.

There are a few approaches to dealing with unconnected GPIO:
1) Leave unused GPIO pins floating. In software, confirm that they are configured as inputs and enable their respective on-chip internal pullup (via GP*PUD). Note that, depending on the device and the GPIO#, some pullups may be on or off at reset.
2) Leave unused GPIO pins floating. In software, configure the GPIOs as outputs and drive them either high or low (if low, you should make sure that the internal pull-up is off to save power)
3) Pull unused GPIOs high externally via resistors.

1 & 2 should be similarly fine. 3 is extra safe.

More thoughts:
https://e2e.ti.com/support/microcontrollers/c2000/w/design_notes/3148.gpio-unused-pins-suggested-connections

Thank you,
Brett

0 Gautam Iyer over 10 years ago

Guru 192875 points

Hi Rasit,

I prefer connecting them to GND (pull it down).

Regards,
Gautam

C2000™︎ microcontrollers

C2000 microcontrollers forum

Unused GPIO pins for TMS320F28035