Ruby + GPIO + RVM：权限被拒绝

Question

当尝试使用各种宝石（wirespi，pi_piper，ruby-gpio，rpi_gpio）使用带有ruby的GPIO时，我尝试运行脚本来控制GPIO引脚时出现“Permission Denied”错误。我正在使用RVM来管理gemsets和版本，所以使用sudo根本无法帮助我。有没有允许在GPIO引脚上进行通信？

(ssh) pi@raspberrypi : ~/ruby/gpio/led_flash
[127] % ./led_flash.rb
/home/pi/.rvm/gems/ruby-1.9.3-p551/gems/ruby-gpio-0.0.2/lib/ruby-gpio.rb:111:in `initialize': Permission denied - /sys/class/gpio/gpio17/direction (Errno::EACCES)
        from /home/pi/.rvm/gems/ruby-1.9.3-p551/gems/ruby-gpio-0.0.2/lib/ruby-gpio.rb:111:in `open'
        from /home/pi/.rvm/gems/ruby-1.9.3-p551/gems/ruby-gpio-0.0.2/lib/ruby-gpio.rb:111:in `write'
        from /home/pi/.rvm/gems/ruby-1.9.3-p551/gems/ruby-gpio-0.0.2/lib/ruby-gpio.rb:27:in `as'
        from ./led_flash.rb:6:in `block in <main>'
        from /home/pi/.rvm/gems/ruby-1.9.3-p551/gems/ruby-gpio-0.0.2/lib/ruby-gpio.rb:82:in `instance_eval'
        from /home/pi/.rvm/gems/ruby-1.9.3-p551/gems/ruby-gpio-0.0.2/lib/ruby-gpio.rb:82:in `access'
        from ./led_flash.rb:5:in `<main>'

有问题的剧本

#! /usr/bin/env ruby

require 'ruby-gpio'

GPIO.access(led: 17, button: 18) do
  led.as :out
  button.as :in
  led.off

  button.async.watch_once_for(1) do
    if led.read == 1
      led.off
    else
      led.on
    end
  end

  sleep
end