CC3220SF: unused GPIO

kwon

Intellectual 860 points

Part Number: CC3220SF
Other Parts Discussed in Thread: CC3235SF

Tool/software:

Hi~

Do you have any recommendations for unused gpio pins? (pull-up, pull-down, floating?)

Datasheet has no description.

In the case of cc3235sf, [Table 4-6. Connections for Unused Pins] says Leave unused GPIOs as NC.

Thanks.

17 days ago

0 Jan D 17 days ago

Guru 78225 points

Hi,

Basic princesses for CC3220 are same as for any other low power MCU.

Common practice is to use unused GPIO pins as output. If pin has integrated pull-up resistor (or enabled optional pull-up), it should be set output GPIO state to high. At other cases you can set output state to low. You should never set pin as GPIO input if pin is NC. This will increase power consumption (floating pin can cause increased power consumption due to oscillating of Schmitt trigger inside GPIO).

Jan

0 kwon 17 days ago in reply to Jan D

Intellectual 860 points

Hi Jan,

Below it says to connect a 2.7k pull-down resistor.

https://e2e.ti.com/support/wireless-connectivity/wi-fi-group/wifi/f/wi-fi-forum/942363/cc3220s-floating-pins?tisearch=e2e-sitesearch&keymatch=CC3220%25252520UNUSED#

To summarize the two answers:

1. set to output => n.c

2. set to input & unless programmed by the MCU => 2.7k pull-down resistor connected

Is this correct?

Best regards,

KWON.

0 Jan D 17 days ago in reply to kwon

Guru 78225 points

Hi,

External pull-up may to useful when you have concerns of line state when device boots or it is at bootloader state. But generally external pull-ups are not needed.

Generally state of pin does not mater. Only important thing is to NOT use pin as input without any pull-up/pull-down (external or internal).

Jan

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CC3220SF: unused GPIO