Accessing GPIO ports from a user `C' program

HI,

I know how to access and configure GPIO ports from the kernel, but now need
to control an output pin from a `user' program.

I have done this before on the pxa-255-arm, and know it involves
accessing the physical memory space using /dev/mem
to hit the registers and register config directly.

WHAT I would really like is an API that does this all for me !
All I want to do is control one logical output pin, but
it is too slow to do this through the filesystem (I am controlling
the data direction on RS-485, with a modbus timeout constraint).

Is there an API on pico mod for control of I/O pins directly from `C'.

Robin

Can you send me the ARM datasheet for the processor on the pico mod.

I tried to get it from samsung but they won't recognise energytechnologycontrol.com as a valid
company url for email

What I really want is to be able to see how many characters are in the UART buffer.

I am using the serial comms with an additional RS485 TX ENABLE.

I call a device driver to call a delay, and then request the data to be sent.

The delay in the serial data being sent is very variable.

Usually around 4mS but up to 20ms is not unusual.

I find this a bit strange, because really all it has to do is bung
the data in a FIFO on the arm chip (if its similar to the
gumstix pxa based arm chip ~ which we do have the data sheet for).

What I would rather do is make a simple char driver for my RS485 output port.
But for that I need the S3 data sheet