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| Both sides previous revisionPrevious revisionNext revision | Previous revision | ||
| en:examples:timer:delay [2015/11/05 10:04] – heikopikner | en:examples:timer:delay [2020/07/20 09:00] (current) – external edit 127.0.0.1 | ||
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| Line 1: | Line 1: | ||
| - | ~~PB~~ | + | < |
| ====== Delay ====== | ====== Delay ====== | ||
| Line 63: | Line 63: | ||
| <code c> | <code c> | ||
| - | // Software delay in milliseconds. | + | // Software delay in milliseconds |
| void sw_delay_ms(unsigned short count) | void sw_delay_ms(unsigned short count) | ||
| { | { | ||
| Line 69: | Line 69: | ||
| while (count-- > 0) | while (count-- > 0) | ||
| { | { | ||
| - | // 1ms delay with a special function. | + | // 1ms delay with a special function |
| _delay_ms(1); | _delay_ms(1); | ||
| } | } | ||
| Line 78: | Line 78: | ||
| <code c> | <code c> | ||
| - | // The demonstration program of the software delay of the HomeLab. | + | // The demonstration program of the software delay of the HomeLab |
| - | // The program is blinking a LED for a moment after ~1 second. | + | // The program is blinking a LED for a moment after ~1 second |
| #include < | #include < | ||
| #include < | #include < | ||
| Line 86: | Line 86: | ||
| int main(void) | int main(void) | ||
| { | { | ||
| - | // Setting the pin of the LED as output. | + | // Setting the pin of the LED as output |
| pin_setup_output(led_debug); | pin_setup_output(led_debug); | ||
| Line 101: | Line 101: | ||
| pin_set(led_debug); | pin_set(led_debug); | ||
| - | // Software delay for 900 milliseconds. | + | // Software delay for 900 milliseconds |
| sw_delay_ms(900); | sw_delay_ms(900); | ||
| } | } | ||
| Line 115: | Line 115: | ||
| <code c> | <code c> | ||
| - | // Hardware delay in milliseconds. | + | // Hardware delay in milliseconds |
| void hw_delay_ms(unsigned short count) | void hw_delay_ms(unsigned short count) | ||
| { | { | ||
| - | // Calculating the initial value of the timer. | + | // Calculating the initial value of the timer |
| register unsigned char timer_start = 256 - F_CPU / 1000 / 64; | register unsigned char timer_start = 256 - F_CPU / 1000 / 64; | ||
| - | // Starting the timer. | + | // Starting the timer |
| timer0_init_normal(TIMER0_PRESCALE_64); | timer0_init_normal(TIMER0_PRESCALE_64); | ||
| - | // Counting the variable of the delay to the 0. | + | // Counting the variable of the delay to the 0 |
| while (count-- > 0) | while (count-- > 0) | ||
| { | { | ||
| - | // Initializing the timer. | + | // Initializing the timer |
| timer0_set_value(timer_start); | timer0_set_value(timer_start); | ||
| - | // Zeroing the overflow flag. | + | // Zeroing the overflow flag |
| timer0_overflow_flag_clear(); | timer0_overflow_flag_clear(); | ||
| - | // Waiting for overflow. | + | // Waiting for overflow |
| while (!timer0_overflow_flag_is_set()) | while (!timer0_overflow_flag_is_set()) | ||
| { | { | ||
| Line 140: | Line 140: | ||
| } | } | ||
| - | // Zeroing the overflow flag. | + | // Zeroing the overflow flag |
| timer0_overflow_flag_clear(); | timer0_overflow_flag_clear(); | ||
| - | // Stoping the timer. | + | // Stoping the timer |
| timer0_stop(); | timer0_stop(); | ||
| + | } | ||
| + | </ | ||
| + | |||
| + | Referenced delay function uses a timer library whose source code for ATmega controller looks like the following: | ||
| + | |||
| + | <code c> | ||
| + | // Timer 0 prescaler selection type | ||
| + | typedef enum | ||
| + | { | ||
| + | TIMER0_NO_PRESCALE | ||
| + | TIMER0_PRESCALE_8 | ||
| + | TIMER0_PRESCALE_32 | ||
| + | TIMER0_PRESCALE_64 | ||
| + | TIMER0_PRESCALE_128 | ||
| + | TIMER0_PRESCALE_256 | ||
| + | TIMER0_PRESCALE_1024 | ||
| + | } | ||
| + | timer0_prescale; | ||
| + | |||
| + | // Setting Timer 0 to a normal mode | ||
| + | inline void timer0_init_normal(timer0_prescale prescale) | ||
| + | { | ||
| + | TCCR0 = prescale & 0x07; | ||
| + | } | ||
| + | |||
| + | // Stopping the Taimer 0 | ||
| + | inline void timer0_stop() | ||
| + | { | ||
| + | TCCR0 = 0x00; | ||
| + | } | ||
| + | |||
| + | // Taimer 0 value set | ||
| + | inline void timer0_set_value(unsigned char value) | ||
| + | { | ||
| + | TCNT0 = value; | ||
| + | } | ||
| + | |||
| + | // Timer 0 overflow flag clear | ||
| + | inline void timer0_overflow_flag_clear(void) | ||
| + | { | ||
| + | bit_set(TIFR, | ||
| + | } | ||
| + | |||
| + | // Timer 0 overflow flag state reading | ||
| + | inline bool timer0_overflow_flag_is_set(void) | ||
| + | { | ||
| + | return (bit_is_set(TIFR, | ||
| } | } | ||
| </ | </ | ||
| Line 151: | Line 198: | ||
| <code c> | <code c> | ||
| - | // Demonstration program of hardware delay of the HomeLab. | + | // Demonstration program of hardware delay of the HomeLab |
| - | // The Program blinks LED for a moment after every ~1 second. | + | // The Program blinks LED for a moment after every ~1 second |
| #include < | #include < | ||
| #include < | #include < | ||
| - | // Main program. | + | // Main program |
| int main(void) | int main(void) | ||
| { | { | ||
| - | // Setting the pin of the LED as output. | + | // Setting the pin of the LED as output |
| pin_setup_output(led_debug); | pin_setup_output(led_debug); | ||
| - | // Endless loop. | + | // Endless loop |
| while (true) | while (true) | ||
| { | { | ||
| - | // Lighting the LED. | + | // Lighting the LED |
| pin_clear(led_debug); | pin_clear(led_debug); | ||
| - | // Hardware delay for 100 milliseconds. | + | // Hardware delay for 100 milliseconds |
| hw_delay_ms(100); | hw_delay_ms(100); | ||
| - | // Switch off of the LED. | + | // Switch off of the LED |
| pin_set(led_debug); | pin_set(led_debug); | ||
| - | // Hardware delay for 900 milliseconds. | + | // Hardware delay for 900 milliseconds |
| hw_delay_ms(900); | hw_delay_ms(900); | ||
| } | } | ||
