GPIO24 and SMS


I configure the GPIO 24 to an input GPIO.
When subscribing to the GPIO handler, the handler is called and the read value is 0 (that I was expecting) :
GPIO 24: 0

My application manages incoming SMS (by parsing incoming SMS to do some stuff).
But when my application receives an SMS, the GPIO handler is called twice and the read value is 1 and after 0 !
GPIO 24: 1
GPIO 24: 0

Why the GPIO 24 reacts when the application receive the SMS ?

Thanks !

is that gpio connected to anyting yet?
it’s not multiplexed with anything, so the OS doesn’t (or shouldn’t) touch it.

the reset stat of that gpio is Z, so it’s no pulled up or down, but left floating.
maybe the EMI from receiving the sms is enough to trigger it from 0 to 1 and back.


What do you mind by “maybe the EMI from receiving the sms is enough to trigger it from 0 to 1 and back” ? (My english is quite poor :confused: )

Moreover, this problem has occured since I’ve upgrated the firmware from the R72 to R73 version…


Does somebody notice the same “problem” ?

What can I do wrong ?

by that i mean that the radiation in the air (that also makes your speakers go ticktick) when receiving an sms is disturbing the state of the GPIO.

but if it never happened to you before then maybe it has got something to do with the upgrade

Ok I understand ! :slight_smile:

I think it has got someting to do with the update… Do you known if there is a R73 support somewhere ?

i think your best shot would be contacting your distributor.

another thing you can try is measuring the gpio24 to see if the pin state is really changed or the problem is only internal to the module?

You completly right it seems to be a “disturbing” problem !!! Today the problem doesn’t occured !! And if it occure again I will measure the gpio24 ! Many thanks !!!

do you connect or intend to use the gpio in the future?
because connecting a pullup or pulldown resistor to the input will stop this ‘undefined’ behaviour from occuring.

wich by the way is always a good practice.
always make sure that inputs you subscribe to have a ‘defined’ state.

Ok ! I intend to use the gpio in the future !

I’m newby in the embedded world and I need to learn all this good practice :slight_smile: !!!

Many thanks for resolving my “false” problem !

to think that I have been searching for a way of setting a weak pullup on
a GPIO input!. In the end, I botched it by putting 100K pullup.
I’m used to using PICS and other suchlike kit where one can actually
control what is going on!