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  1. README.md
doc/README.md

GPIO testport for use with Titan test executor on Raspberry Pi

General introduction

Titan is a TTCN-3 compiler and test executor, which is able to run on the Raspberry Pi (model 2B and 3B were tested). GPIO (general purpose input/output) pins on the Raspberry Pi are able to control and/or receive signals from physical computing devices (leds, buttons, valves, etc...). Testports are programmable connections between Titan and any physical interface on a device, in this case GPIO pins on the Raspberry Pi.

The current implementation is using the sysfs interface to access GPIO pins.

Usage

Preparations

  • In Your TTCN-3 module the GPIOPinPort module must be included:

    import from GPIOPinPort all;

  • Create a component in the module:

** Recommended way: extend the GPIO_Base component in GPIOPinPort module where the whole GPIO is declared as a port array

type component GPIO extends GPIO_Base { <Your code> }

** Custom solution: *** !!Important: the name of the port instance MUST be either gpio# or in case of port arrays gpio[#], where # is an integer between (and including) 2 and 27, which will be the actual pin number of the GPIO!

type component GPIO {
port GPIO_Pin_Port gpio27;
port GPIO_Pin_Port gpio[2..26];
    timer t_short;
}

  • Map any or all the ports You want to use:

    map(self:gpio[11], system:gpio[11]); map(self:gpio27, system:gpio27); map(self:gpio[26], system:gpio[26]);

Setting a pin to output, and setting the value of the pin

  • To set direction on the gpio pin to OUT a “send” operation is to be performed:

    var GPIO_PIN_DIRECTION gpio27_direction := OUT; gpio27.send(gpio27_direction);

  • Similarly, to set the value (HIGH/LOW) a “send” operation is to be performed:

    var GPIO_PIN_VALUE gpio27_value := HIGH; gpio27.send(gpio27_value);

Listening for input changes on pin(s)

  • Please note that without an actual physical circuit connected to the pins no relyable state can be read as the state of a pin is “undefined”.

    var integer v_index;

    var GPIO_PIN_DIRECTION gpio_direction_in := IN; gpio[26].send(gpio_direction_in); gpio27.send(gpio_direction_in);

    t_short.start(5.0);

    alt { [] gpio27.receive { setverdict(pass,“message received on port index 27”); } [] any from gpio.receive -> @index value v_index { setverdict(fail,"unexpected message received on port index: ",v_index); } [] t_short.timeout { log(“Timeout while waiting for input to change”); setverdict(inconc); } }

Unmap all the used ports

unmap(self:gpio27, system:gpio27);
unmap(self:gpio[11], system:gpio[11]);
unmap(self:gpio[26], system:gpio[26]);

References