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avr-libc provides a subset of the standard C library for AVR microcontrollers.

Using avr-libc. avr-libc provides a subset of the standard C library for AVR microcontrollers. avr-libc also provides necessary startup code for most applications. Details (oh, are there details) are linked from the class web page at:

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avr-libc provides a subset of the standard C library for AVR microcontrollers.

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  1. Using avr-libc avr-libc provides a subset of the standard C library for AVR microcontrollers. avr-libc also provides necessary startup code for most applications. Details (oh, are there details) are linked from the class web page at: Many categories of libc modules to make embedded programming easier: -Delay loops -EEPROM access -character operations -integer conversions -math operations -string operations -interrupts http://www.nongnu.org/avr-libc/user-manual/index.html

  2. Using avr-libc More examples using avr-libc Character operations... #include <string.h> //right justify results on the LCD for(i=0; i<=(14–(strlen(lcd_str) + strlen(lcd_str1))); i++) char2lcd(‘ ‘); Fake floating point math and print results #include <stdlib.h> div_t fp_adc_result, fp_low_result; //double fp_adc_result; fp_adc_result = div(adc_result, 205); //should be 204.8 to be exact low = fp_adc_result.rem; high = fp_adc_result.quot; fp_low_result = div((low*100), 205); //set decimal fraction itoa(fp_low_result.quot, lcd_str, 10); //convert to ascii string itoa(high, lcd_str1, 10); //convert to ascii string Convert integers to ascii scring

  3. Using avr-libc Examples using avr-libc Character conversion: Setup a interrupt service routine. The ISR created will save registers for you and will disable interrupts when entering the ISR. #include <stdlib.h> itoa(frequency, lcd_freq_str, 10); //convert integer to ASCII string #include <avr/interrupt.h> /***********************************************************************/ // timer/counter 1 ISR //When the TCNT1 compare1A interrupt occurs, port F bit 4 is toggled. //This creates the alarm sound from the clock. /***********************************************************************/ ISR(TIMER1_COMPA_vect){ if (alarm_enable == 1) //toggle port F bit 4 if valid button pushed PORTF ^= 0x10; }//ISR

  4. Using avr-libc Examples using avr-libc Generating timing delays: Note: compiler optimizations must be enabled and the delay time must be an expression that is a known constant at compile-time. #defineF_CPU must be defined as a constant. It defines the CPU clock frequency (in Hertz). The maximal possible delay is 262.14 ms / F_CPU in MHz. If the user requests more delay, resolution is limited to 0.1mS and user will not be notified. See avr-libc Function Documentation for details. There is also a _delay_us function for smaller delays. #define F_CPU 16000000UL //16Mhz #include <util/delay.h> for(i=0; i<=3; i++) {_delay_ms(250);} //delay for 1 sec

  5. Using avr-libc Examples using avr-libc Accessing EEPROM memory: #include <avr/eeprom.h> /***********************************************************************/ // save_settings //Saves user settings into EEPROM when power is going down. void save_settings(){ eeprom_write_byte(&eeprom_alarm_volume, alarm_volume); eeprom_write_byte(&eeprom_alarm_level, alarm_level); }//save_settings /***********************************************************************/

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