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--- getting_started:tutorials:hal3 [2020/12/03 12:03] – removed ursgraf
+++ getting_started:tutorials:hal3 [2026/05/13 10:55] (current) – ursgraf
@@ Line 1: / Line 1: @@
+====== Using the HAL with the GPIO Subsystem ======
+In the EEROS library you will find a directory with examples. For this example see [[https://github.com/eeros-project/eeros-framework/blob/master/examples/hal/HalTest4.cpp|HalTest4.cpp]].
+The system either uses real hardware inputs and output or makes use of a simulated gpio device. You need to install the necessary wrapper library for gpio, see [[getting_started:install_wrapper|]].
+When using a simulated gpio device, make sure to load the kernel driver first and then create the device with
+<code>
+$ sudo modprobe gpio-sim
+$ sudo mkdir /sys/kernel/config/gpio-sim/ofagpio
+$ sudo mkdir /sys/kernel/config/gpio-sim/ofagpio/bank0
+$ echo 32 | sudo tee /sys/kernel/config/gpio-sim/ofagpio/bank0/num_lines
+$ echo 1 | sudo tee /sys/kernel/config/gpio-sim/ofagpio/live
+</code>
+Make sure that your local user has access to the device file.
+<code>
+$ sudo chown $USER:$USER /dev/gpiochip0
+</code>
+Open a shell in the build directory of your EEROS library and run
+<code>
+$ ./examples/hal/halTest4 -c HalTest4ConfigGpio.json
+</code>
+It will start in safety level //slOne// and mirror the digital input channel 1 to output channel 0. You can check this behavior with
+<code>
+$ echo pull-up | sudo tee /sys/devices/platform/gpio-sim.0/gpiochip0/sim_gpio1/pull
+</code>
+or
+<code>
+$ echo pull-down | sudo tee /sys/devices/platform/gpio-sim.0/gpiochip0/sim_gpio1/pull
+</code>
+while reading the state of channel 0 with
+<code>
+$ cat /sys/devices/platform/gpio-sim.0/gpiochip0/sim_gpio0/value
+</code>
+Next, change the state of channel 16. This is a critical input in the safety system and causes a transition to safety level //slTwo// when pulled up.
+<code>
+$ echo pull-up | sudo tee /sys/devices/platform/gpio-sim.0/gpiochip0/sim_gpio16/pull
+</code>
+To change back to //slOne// change the level back to '0'.
+<code>
+$ echo pull-down | sudo tee /sys/devices/platform/gpio-sim.0/gpiochip0/sim_gpio16/pull
+</code>