9. Embedded programming¶

ROJECT=Blinkled
SOURCES=$(PROJECT).c
MMCU=attiny84
F_CPU = 20000000

CFLAGS=-mmcu=$(MMCU) -Wall -Os -DF_CPU=$(F_CPU)

$(PROJECT).hex: $(PROJECT).out
    avr-objcopy -O ihex $(PROJECT).out $(PROJECT).c.hex;\
    avr-size --mcu=$(MMCU) --format=avr $(PROJECT).out

$(PROJECT).out: $(SOURCES)
    avr-gcc $(CFLAGS) -I./ -o $(PROJECT).out $(SOURCES)

program-bsd: $(PROJECT).hex
    avrdude -p t84 -c bsd -U flash:w:$(PROJECT).c.hex

program-dasa: $(PROJECT).hex
    avrdude -p t84 -P /dev/ttyUSB0 -c dasa -U flash:w:$(PROJECT).c.hex

program-avrisp2: $(PROJECT).hex
    avrdude -p t84 -P usb -c avrisp2 -U flash:w:$(PROJECT).c.hex

program-avrisp2-fuses: $(PROJECT).hex
    avrdude -p t84 -P usb -c avrisp2 -U lfuse:w:0x5E:m

program-usbtiny: $(PROJECT).hex
    avrdude -p t84 -P usb -c usbtiny -U flash:w:$(PROJECT).c.hex

program-usbtiny-fuses: $(PROJECT).hex
    avrdude -p t84 -P usb -c usbtiny -U lfuse:w:0x5E:m

program-dragon: $(PROJECT).hex
    avrdude -p t84 -P usb -c dragon_isp -U flash:w:$(PROJECT).c.hex

program-ice: $(PROJECT).hex
    avrdude -p t84 -P usb -c atmelice_isp -U flash:w:$(PROJECT).c.hex

// Blinkled.c
 //
 // 115200 baud messages on button press + led blinking
 //
 // set lfuse to 0x5E for 20 MHz xtal
 //
 // Ch_R
 // 2019-03-19
 //
 // Based on Neil Gershenfeld's  hello.ftdi.44.echo.interrupt.c
 //
 // (c) Massachusetts Institute of Technology 2010
 // This work may be reproduced, modified, distributed,
 // performed, and displayed for any purpose. Copyright is
 // retained and must be preserved. The work is provided
 // as is; no warranty is provided, and users accept all
 // liability.
 //

 #include <avr/io.h>
 #include <util/delay.h>
 #include <avr/pgmspace.h>

 #define output(directions,pin) (directions |= pin) // set port direction for output
 #define input(directions,pin) (directions &= (~pin)) //set port direction for input
 #define set(port,pin) (port |= pin) // set port pin
 #define clear(port,pin) (port &= (~pin)) // clear port pin
 #define toggle(port,pin) (port ^= pin) // toggle port pin
 #define pin_test(pins,pin) (pins & pin) // test for port pin
 #define bit_test(byte,bit) (byte & (1 << bit)) // test for bit set
 #define bit_delay_time 8.25 // bit delay for 115200 with overhead
 #define bit_delay() _delay_us(bit_delay_time) // RS232 bit delay
 #define half_bit_delay() _delay_us(bit_delay_time/2) // RS232 half bit delay
 #define char_delay() _delay_ms(10) // char delay

//Pins definitions
 #define serial_port PORTA
 #define serial_direction DDRA
 #define serial_pins PINA
 #define serial_pin_in (1 << PA0)
 #define serial_pin_out (1 << PA1)
 #define led_port PORTA
 #define led_direction DDRA
 #define led_pins PINA
 #define led_pin (1 << PA2)
 #define led PA2
 #define button_port PORTB
 #define button_direction DDRB
 #define button_pins PINB
 #define button_pin (1 << PB2)
 #define button PB2
//end Pins Definitions

 void put_char(volatile unsigned char *port, unsigned char pin, char txchar) {
    //
    // send character in txchar on port pin
    //    assumes line driver (inverts bits)
    //
    // start bit
    //
    clear(*port,pin);
    bit_delay();
    //
    // unrolled loop to write data bits
    //
    if bit_test(txchar,0)
       set(*port,pin);
    else
       clear(*port,pin);
    bit_delay();
    if bit_test(txchar,1)
       set(*port,pin);
    else
       clear(*port,pin);
    bit_delay();
    if bit_test(txchar,2)
       set(*port,pin);
    else
       clear(*port,pin);
    bit_delay();
    if bit_test(txchar,3)
       set(*port,pin);
    else
       clear(*port,pin);
    bit_delay();
    if bit_test(txchar,4)
       set(*port,pin);
    else
       clear(*port,pin);
    bit_delay();
    if bit_test(txchar,5)
       set(*port,pin);
    else
       clear(*port,pin);
    bit_delay();
    if bit_test(txchar,6)
       set(*port,pin);
    else
       clear(*port,pin);
    bit_delay();
    if bit_test(txchar,7)
       set(*port,pin);
    else
       clear(*port,pin);
    bit_delay();
    //
    // stop bit
    //
    set(*port,pin);
    bit_delay();
    }

 void put_string(volatile unsigned char *port, unsigned char pin, char *str) {
    //
    // print a null-terminated string
    //
    static int index;
    index = 0;
    do {
       put_char(port, pin, str[index]);
       ++index;
       } while (str[index] != 0);
    }


 int main(void) {
    //
    // main function
    //

    unsigned char was_active = 0; //unsigned char used as boolean

    // set clock divider to /1
    //
    CLKPR = (1 << CLKPCE);
    CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);

    //
    // initialize output pins
    // (pins are input by default)
    //
    set(serial_port, serial_pin_out);
    output(serial_direction, serial_pin_out);

    set(led_port, led_pin);
    output(led_direction, led_pin);


    //
    // main loop
    //
    while (1) { //loop forever (1 is equivalent to "true")
       if bit_test(button_pins, button){     //test wether the button is pressed : if not... (level it then high)
         clear(led_port, led_pin);         //if not, light the led off
           if(was_active){                   //if it was pressed during the last loop, put an "exit message"
                 put_string(&serial_port, serial_pin_out, "Ho no, you realesed me");
                 put_char(&serial_port, serial_pin_out, 10); // new line
                 was_active=0; //disable the was_active flag
           }
       }
       else{       //if the button was pressed
            toggle(led_port, led_pin);      //change the led status to blink it
            put_string(&serial_port, serial_pin_out, "You pressed me , Youhouuuuuuu");
            put_char(&serial_port, serial_pin_out, 10); // new line
            _delay_ms(200) ; //wait a bit before going to the next loop (blinking visibily AND button debouncing)
             was_active=1 ;    //change the was_active flag so that an exit message will be send on button release
       }
    }
 }