GPIO pins 5v tolerant?

hi guys

i want to setup up 1-wire temperature sensors like this.
http://foxg20.acmesystems.it/doku.php?id=tutorial:1wire

i use con4 
pin 1 for 5v
pin 3 for gnd
pin 9 for data

got everything up and running, but without the 4k7 pullup resistor.
now some sensors got long cable and i have to use the pullups.

when i connect the pullup, i get 5v on pin 9,
is the gpio 5v tolerant.

in the datasheet section 27 and table 27-1 says:

DC Input Voltage  VIN    3.3V Input buffer                           4.8V
                         3.3V Interface / 5V Tolerant input buffer   6.5V

now, does this refer to the GPIO?

thanks in advance
rudi

My recollection is that some of the GPIO pins are 5V tolerant. A close
inspection of the datasheet should reveal which ones.

Dave

Well, I think that may be true of the S3C2410, but not the S3C2440.

Search <5V tolerant> for previous threads.

I'll ask the hardware guy tomorrow.

Dave

hi dave

that is my problem, in the datasheet i didn´t found anything in that
direction. :-(
all pins are listet in thi IO part, but nothing about 5v tolerant.

already search here, but i didn´t found a thread with a clear answer.
whould be graet if you could get the info fpr me!

regard
rudi

Unfortunately, there doesn't seem to be any S3C2440 experience here,just
S3C2410.  

A suggestion is to determine whether or not the GPIO pins have internal
Schottky diodes, if so an external current limiting resistor should allow
you to feed a 5Volt signal in.  If they don't have internal diodes you
could place a suitable external diode (slightly less than 3V3) and a
current limiting resistor.

Perhaps an email to Samsung support should get a definitive answer.

Good luck,
Dave

I have connected a 5V RFID module to the board (CON1).

Perhaps an email to Samsung support should get a definitive answer.

i register myself @samsung today and wait for the verify.
after that i can drop my question there.

regards
rudi

still waiting for my register verify email?

somebody got a account @samsung?

regards
rudi

I have sent a request to Samsung support, as follows:

***
Are any GPIO pins 5 Volt tolerant on the S3C2440?

There is a mention of "5 Volt buffers" in the datasheet, but no GPIO seems
to be tagged as 5 Volt tolerant.

Some GPIO on the S3C2410 were tagged <t6>, which identified which pins were
5 Volt tolerant.

If no GPIO is 5Volt tolerant on the S3C2440 are there internal Schottky
diodes on some or all of the GPIO pins?
***

Probably will take a week or so.

Regards,
Dave

hi dave

thx, I register on this site
http://www.samsung.com/global/business/semiconductor/productInfo.do?fmly...

don´t no if my email been dropt in japan somewhere,
i think they got other problems there at the moment.

where did you dropt your question?

regards
rudi

They are in South Korea.

I had to go through one of our company component engineers, who in turn is
asking Samsung support people in Australia.

ok, then we must wait and see.

still haven´t recieved a verify email :-(

i also recent the question.

after one week i got a email telling me,
my answer is been forward to xxxxx,
and still nothing after 3 weeks :-(

i found out that the 1wire gio-master driver is not the best to use in
userspace etc 
because 1-wire is a bit time critical.

my 8 sensors work well with a 10cm floppy cabel,
but if i switch to longer cat5 cable, only crap.

few guys told me to use a ather 1-wire master,
and now i got a DS9490R and everything works like a charm.

6 sensors on a 6m cat5 cable
1 sensor on a 6m cable
1 sensor on a 30m cable

will post the repy from samsung when it drop in.

My request was sent to Singapore support and still no response either.

Dave

Rudi,

The answer I got back was to look at the datasheet for the S3C2450 as "it
is a more stable product".  By that, I think they mean it is a newer
product.

You have to register using a company email to get further info and I
suspect that will not tell us what we want to know.

You have to register using a company email to get further info and I
suspect that will not tell us what we want to know.

i already tried that out, see my link way up here.
after 2 weeks i got an email with a sorry, no access where permittet to
download more pdf files for me. :-(
they don´t like my emailadress/company name :-(

then i drop my question on a other place and got this email 31.03.2011

Hello xxxxxx ,
Thank you for your inquiry to Samsung Semiconductor.

Our Europe FAE will help you promptly.

If you have any further questions, please send us more question again or
visit our Homepage(http://www.samsungsemi.com).

Sincerely,
Semiconductor Business
Samsung Electronics Co,.Ltd.

ok, still waiting for a answer here

Rudi,

One somehow gets the impression that either they think you are asking for
the photomasks to copy the die OR they just have not tested the device to
determine what the safe limits are.

Could you not apply the protective measures suggested further up?  If you
know the maximum voltage can not go above 5.0Volts could you place a high
value voltage divider network so that the input would never go above 3V3.

Say a a 180K series resistor with a 330K resistor to ground and then to the
input.  The input impedance of the ADC pins is pretty high, from memory. 
You will lose some resolution.

Good luck,

Dave