BASH functions for using the C.H.I.P. GPIO pins.

gpio.sh

#!/bin/bash
GPIO_OFFSET=408
CSI_OFFSET=132

#FIXME Add usage() function to improve documentation

# Enable exposure of the specified GPIO pin (0-8)
gpio_enable()
{
  if [[("$1" -lt 0) || ("$1" -gt 8)]] ; then
    echo "Valid pins are 0-8"
    return -1;
  fi
  PIN=$(($GPIO_OFFSET + $1));
  sudo sh -c "echo $PIN > /sys/class/gpio/export"
}
# Disables exposure of the specified GPIO pin (0-8)
gpio_disable()
{
  if [[("$1" -lt 0) || ("$1" -gt 8)]] ; then
    echo "Valid pins are 0-8"
    return -1;
  fi
  PIN=$(($GPIO_OFFSET + $1));
  sudo sh -c "echo $PIN > /sys/class/gpio/unexport"
}
# Sets the pin to input or output mode
gpio_mode()
{
  if [[("$1" -lt 0) || ("$1" -gt 8)]] ; then
    echo "Valid pins are 0-8"
    return -1;
  fi
  PIN=$(($GPIO_OFFSET + $1));
  if [[ ! -d /sys/class/gpio/gpio$PIN ]] ; then
    echo "GPIO$1 has not been enabled yet, please call gpio_enable"
    return -1
  fi
  if [ $# -lt 2 ] ; then
    cat /sys/class/gpio/gpio$PIN/direction
  else
    MODE=""
    if [[("$2" == "in") || ("$2" == "IN")]] ; then
      MODE="in"
    elif [[("$2" == "out") || ("$2" == "OUT")]] ; then
      MODE="out"
    fi
    if [[ "$MODE" == "" ]] ; then
      echo 'Valid modes are "in" or "out"'
      return -1;
    fi
    sudo sh -c "echo $MODE > /sys/class/gpio/gpio$PIN/direction"
  fi
}
gpio_write()
{
  if [[("$#" -lt 2)]] ; then
    echo "Usage: gpio_write pin value"
    return -1
  fi
  if [[("$1" -lt 0) || ("$1" -gt 8)]] ; then
    echo "Valid pins are 0-8"
    return -1;
  fi
  PIN=$(($GPIO_OFFSET + $1));
  #FIXME - Accept more than one word
  sudo sh -c "echo $2 > /sys/class/gpio/gpio$PIN/value"
}
gpio_read()
{
  if [[("$1" -lt 0) || ("$1" -gt 8)]] ; then
    echo "Valid pins are 0-8"
    return -1;
  fi
  PIN=$(($GPIO_OFFSET + $1));
  cat /sys/class/gpio/gpio$PIN/value
}


# Enable exposure of the specified CSI pin (0-8)
csi_enable()
{
  if [[("$1" -lt 0) || ("$1" -gt 8)]] ; then
    echo "Valid pins are 0-8"
    return -1;
  fi
  PIN=$(($CSI_OFFSET + $1));
  sudo sh -c "echo $PIN > /sys/class/gpio/export"
}
# Disables exposure of the specified CSI pin (0-8)
csi_disable()
{
  if [[("$1" -lt 0) || ("$1" -gt 8)]] ; then
    echo "Valid pins are 0-8"
    return -1;
  fi
  PIN=$(($CSI_OFFSET + $1));
  sudo sh -c "echo $PIN > /sys/class/gpio/unexport"
}
# Sets the pin to input or output mode
csi_mode()
{
  if [[("$1" -lt 0) || ("$1" -gt 8)]] ; then
    echo "Valid pins are 0-8"
    return -1;
  fi
  PIN=$(($CSI_OFFSET + $1));
  if [[ ! -d /sys/class/gpio/gpio$PIN ]] ; then
    echo "CSI$1 has not been enabled yet, please call csi_enable"
    return -1
  fi
  if [ $# -lt 2 ] ; then
    cat /sys/class/gpio/gpio$PIN/direction
  else
    MODE=""
    if [[("$2" == "in") || ("$2" == "IN")]] ; then
      MODE="in"
    elif [[("$2" == "out") || ("$2" == "OUT")]] ; then
      MODE="out"
    fi
    if [[ "$MODE" == "" ]] ; then
      echo 'Valid modes are "in" or "out"'
      return -1;
    fi
    sudo sh -c "echo $MODE > /sys/class/gpio/gpio$PIN/direction"
  fi
}
csi_write()
{
  if [[("$#" -lt 2)]] ; then
    echo "Usage: csi_write pin value"
    return -1
  fi
  if [[("$1" -lt 0) || ("$1" -gt 8)]] ; then
    echo "Valid pins are 0-8"
    return -1;
  fi
  PIN=$(($CSI_OFFSET + $1));
  #FIXME - Accept more than one word
  sudo sh -c "echo $2 > /sys/class/gpio/gpio$PIN/value"
}
csi_read()
{
  if [[("$1" -lt 0) || ("$1" -gt 8)]] ; then
    echo "Valid pins are 0-8"
    return -1;
  fi
  PIN=$(($CSI_OFFSET + $1));
  cat /sys/class/gpio/gpio$PIN/value
}

# The MIT License (MIT) Copyright (c) 2016 Jeff Larkin
# modified by Nick Horvath
#
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# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
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