Embedded AVR atmega 8bit GPIO kata

Assignment

The push button S1 shall behave as a toggle switch to turn the led LED1 on and off.

Scenario: Initial state

    Given the device is powered on
    Then the LED is turned off

Scenario: Turn LED on

    Given the device is powered on
    When I press the button
    Then the LED is turned on

Scenario: Turn LED off

    Given the device is powered on
    When I press the button
    And I press the button again
    Then the LED is turned off

Target Hardware

Schematic:

Atmega168 pin configuration:

Build and Run

The qmake project provides the following make targets.

Run the unit tests:

make check

Run the feature tests:

make run-bdd

Download the firmware to the AVR

make flash

AVR GPIO cheatsheet

#ifdef __AVR
// avr-gcc defines preprocessor variable __AVR
#endif

// pin and port definitions
#include <avr/io.h>

// set pin PB0 as output, PB7-PB1 as input
DDRB = _BV(PB0);

// set pin PB0 as input, PB7-PB1 as output
DDRB = ~(_BV(PB0));

// clear PB0
PORTB &= ~(_BV(PB0));

// set PB0
PORTB |= _BV(PB0);

// toggle PB0
PORTB ^= _BV(PB0);

// read port
unsigned port = PINB

// check pin PB0
bool state = PINB & _BV(PB0)