Example Programs There are three example directories that contain examples and instructions for interacting with the GPIO resources on the Atlas-SoC board using the gpio framework provided by the Linux environment.

raw-gpio

A script and two C programs demonstrate how to programmatically detect the state of the KEY0 push button on the Atlas board. The script and one C program simply read the state, output it and exit, the second C program enables the interrupt functionality for the GPIO and waits for the push button press to generate the interrupt that it waits for.

gpio-keys

A script and two C programs demonstrate how to programmatically detect the input events generated by the SW0, SW1, SW2 and SW3 switches on the Atlas-SoC board. The script and one C program simply report the input events as they are detected, the second C program adds a call to the ioctl() function to read the current state of all four switches as each input event is processed.

gpio-leds

A script and a C program demonstrate how to programmatically control the LEDS on the Atlas-SoC board.

Tutorials

The README files in each of the example folders contain detailed instructions, sample scripts and functions for interacting with the board.

If you are using SSH, it is handy to have two terminals open to the same example directory. Display the README file in one terminal (e.g. cat readme_gpio-keys.txt) Copy the example scripts from this terminal and paste into the second terminal as you progress through the tutorial.

If you are using a VNC client: Open the README file with gedit. Open a terminal window and navigate to the example directory. Copy scripts from gedit and paste into the terminal window.

Build Scripts Scripts are provided to build the example applications.

• build_watch_switch_events_ioctl.sh
• build_watch_switch_events.sh
• build_toggle_fpga_leds.sh
• build_poll_KEY0_pb_state.sh
• build_show_KEY0_pb_state.sh

Sandbox Directory The sandbox directory contains source files, scripts, and instructions you can review, run, modify, and recompile the example designs. It also contains a tar ball copy of the entire sandbox contents so they can be restored if needed.

/examples/gpio
├── sandbox
│   ├── gpio-keys
│   │   ├── build_watch_switch_events_ioctl.sh
│   │   ├── build_watch_switch_events.sh
│   │   ├── README_gpio-keys.txt
│   │   ├── watch_switch_events.c
│   │   ├── watch_switch_events_ioctl.c
│   │   └── watch_switch_events.sh
│   ├── gpio-leds
│   │   ├── build_toggle_fpga_leds.sh
│   │   ├── README_gpio-leds.txt
│   │   ├── toggle_fpga_leds.c
│   │   └── toggle_fpga_leds.sh
│   ├── raw-gpio
│   │   ├── build_poll_KEY0_pb_state.sh
│   │   ├── build_show_KEY0_pb_state.sh
│   │   ├── poll_KEY0_pb_state.c
│   │   ├── README_gpio.txt
│   │   ├── show_KEY0_pb_state.c
│   │   └── show_KEY0_pb_state.sh
│   ├── COPYING
│   └── README_first.txt
└── gpio_sandbox.tgz