Using the D.Gilbert gpio utils

An in-deep explanation on how the GPIO lines work and how to manage them faster is available on:

This is a small group of Linux utilities for the Atmel AT91SAM9G25 and AT91SAM9G20 microcontroller units (MCUs). The utilities target The Aria G25 and the FoxG20 boards from Acme Systems and will most likely work on other boards based on the same MCUs. Some of the utilities have the same names as those from the earlier FoxLX board from Acme System; that board was based on the Etrax LX processor from Axis communications.

These utilities mainly work with individual GPIO lines and may be extended to other protocols that can be implemented by "bit banging" GPIO lines. These include I2C (a.k.a. TWI), "one wire" (known as "w1" by the Linux kernel) from Dallas Semiconductor (now Maxim), and the two wire protocol for the SHT-71 .

Compile and build the utilities

Download on your board (not on your Linux workstation) the latest utilities version from the D.Gilbert web server

For the CPUs AT91SAMG20 and AT91SAMG25:

~# wget

For the AT91SAMA5 CPUs:

~# wget

You need to install the xz-utils for the AT91SAMA5:

~# apt-get install xz-utils

Uncompress the .tgz / .tar.xz file

// for the G20 and G25:
~# tar xvzf ag25g20_utils-0.97r14.tgz

// for the A5:
~# tar xvf sama5d3_utils-0.92.tar.xz

If necessary you need to install the tools for compiling on board (remember to have a correct date on your embedded board before installing packages or update):

~# date -s "27 MAR 2019 11:14:00"
~# apt-get update
~# apt-get install build-essential

Compile and install them

// for the G20 and G25:
~# cd ag25g20_utils-0.97r14
~/ag25g20_utils-0.97r14# make
~/ag25g20_utils-0.97r14# make install

// for the A5:
~# cd sama5d3_utils-0.92
~/sama5d3_utils-0.92# make
~/sama5d3_utils-0.92# make install

Using the utilities

Refer to the original README file to learn how to use these utilities

Following is a list of quick examples:

Show the command list

~# g25gpio_status -h               

Get the PIO attributes on given GPIO line

~# g25gpio_status -a -p A
  PIO status: 0 (peripheral ACTIVE)
  PIO output status: 0 (line pure input)
  input filter status: 0 (glitch filter DISabled)
  output data status: 0
  pin data status: 0
  interrupt mask: 0 (DISabled)
  multi driver status: 0 (pin driven high and low)
  pad pull-up status: 0 (ENabled)
  peripheral A function [sr1:0, sr2:0]
  input filter slow clock status: 0 (master-fast)
  pad pull down status: 1 (DISabled)
  additional interrupt modes mask: 0 (Both edges)
  edge/level status: 0 (edge detection)
  fall/rise - low/high status: 0 (falling edge or low level detection)
  locked status: 0 (not locked)
  write protect mode: WPEN: 0 (DISabled)
  schmitt trigger status: 0 (ENabled )
  IO drive: 0 (HI_DRIVE)

of course it is possible to read all the other ports

~# g25gpio_status -a -p B
~# g25gpio_status -a -p C

Set the PIO attributes on given GPIO line

Show the command list

~# g25gpio_set -h               

Disable the pull-up resistor on A/D input lines

~# g25gpio_set -p B -b 11 -u
~# g25gpio_set -p B -b 12 -u
~# g25gpio_set -p B -b 13 -u
~# g25gpio_set -p B -b 14 -u

Enable the low power Suspend To RAM feature on RoadRunner 1.1

~# mem2io -w -i fc040018,300

Related links