Re: [Gumstix-users] GPIO help for Verdex 120pin connector

[SunitM <s.m...@gm...>]

Thanks Dave,

What do the signals labeled CIF do? (from the 120pin connector).

Also, how do you know which is pin 1 on the 120pin connector?  I don't think
I know how to open the schematic.

If I will be using some of those 35 GPIO pins for output, are there any that
I need to tie to pull-up resistors or will they all be able to supply 3.3v
on their own? 

I also wanted to confirm that the max current draw from one of the GPIO pins
is 5mA?



Dave Hylands wrote:
> 
> Hi Sunit,
> 
>>  I am a newbie working on a project where I would like to use 14 GPIO
>> pins
>>  from the 120pin MOLEX connector (I think it's CONN5 on the Verdex) as
>> output
>>  pins to control some other electronics that I have.
>>
>>  I saw post earlier that talked about the 60pin connector and which GPIO
>> pins
>>  would be good to use as to not disrupt any other board functionality.  I
>> am
>>  hoping someone can help me identify 14 pins on the 120pin connector that
>>  could be used as GPIOs.  The functionality that I need for my project is
>>  LCD, touchscreen if possible (but not necessary) and USB host.  I don't
>> need
>>  other things like I2C, SPI or AC97 audio.
> 
> All of the stuff you need goes through the 60-pin hirose, which would
> seem to indicate that all of the GPIOs are available. I count about
> 35.
> <http://docswiki.gumstix.com/120pin_connector_chart>
> 
>>  Also, can someone explain to me what modprobe proc_gpio does?  or what
>>  /proc/gpio is?  I am trying to make sense of it all.
> 
> modprobe proc_gpio causes the proc_gpio.ko loadable module to be
> loaded. Think of it as a way dynamically loading code into the kernel.
> Typically a .ko file will contain a device driver, but it can be
> pretty mcuh any kernel code that you'd like.
> 
> /proc/gpio is a way of manipulating GPIO lines from a shell script or
> from the command line. Very useful for quick and dirty testing or
> debugging, but not particularly useful for actual use, unless you're
> doing low speed I/O.
> 
>>  I also wanted to know if the sample C code by Time Crawford on the
>> docwiki
>>  for gpregs is the best way to set and clear the GPIO lines from my C
>> code?
>>  Are there alternatives?
> 
> mmaping the registeres will certainly give the fastest access to the
> GPIO pins from user space.
> 
> You could use the /proc/gpio interface. You could create your own
> driver for manipulating GPIO pins.
> 
>>  Finally,  I wanted to order some of the MOLEX male connectors that would
>>  connector to my Verdex board.  I wanted to buy only about 5 of them for
>>  prototyping purposes, but have been having a tough time finding
>>  distributors/suppliers.  I am located near Toronto, Canada, but I will
>>  gladly order them from whoever has got them.
> 
> Gumstix sells the 120 pin connectors - I assume that's what you're
> talking about?:
> <http://gumstix.com/store/catalog/product_info.php?cPath=28&products_id=189>
> 
> -- 
> Dave Hylands
> Vancouver, BC, Canada
> http://www.DaveHylands.com/
> 
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