Interfacing Switches with AVR (ATmega16) Mini Development Board
The board has 3 switches (SW1,SW2 & SW3) connected to port pins PD2, PD3 & PD4 via jumpers J7, J8 & J9 respectively. On shorting these jumpers, the switches can be used as pull_up keys and if they are left open, then the port pins can be used independently.
Sample code to test the switches is given below. In the code, switch press is detected by polling and upon pressing a switch, the switch no. gets displayed on the LCD.
Note: To use switches, don’t forget to short the corresponding jumpers J7, J8 & J9. Leaving them open frees PD2, PD3 & PD4 and can be used for any other desired purpose.
Schematic
Sample Code
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/********************************************************************************* HEADER FILES **********************************************************************************/ #define F_CPU 8000000UL /* freq 8 MHz */ #include<avr/io.h> /* Header File Inclusion */ #include<util/delay.h> /* Delay File Inclusion */ /********************************************************************************* FUNCTION DECLARATIONS **********************************************************************************/ void Command(unsigned char cmd); void Data(unsigned char dat); void Display(char loc, const char *LCD); /********************************************************************************* MAIN FUNCTION **********************************************************************************/ int main() { volatile char a=0; DDRB = 0xFF; /* LCD data lines */ DDRD = 0X62; /* LCD Control lines(RS(PD5),RW(GND), EN(PD6),PD2-PD4 keys */ PORTD = 0x1C; /* setting PORTD pins */ _delay_us(15); /* Min Delay To Power LCD to Rx Mode */ Command(0x30); /* LCD Specification Cmdmands */ _delay_us(5); Command(0x30); /* LCD Specification Cmdmands */ _delay_us(2); Command(0x30); /* LCD Specification Cmdmands */ Command(0x38); /* LCD Double Line Display Cmdmand */ Command(0x06); /* LCD Auto Increment Location Cmdmand */ Command(0x0C); /* LCD Display ON Cmdmand */ Command(0x01); /* LCD Display Clear Cmdmand */ _delay_us(1200); Display(0x80, " Press Key : "); while(1) { Command(0x8D); a = PIND&0X1C; /* 0X1C & with PORTD */ if( a != 0X1C ) /* checking if any key is pressed */ { _delay_ms(100); if (a==0x18) /* Accesed when the 1st key is pressed */ { Data('1'); _delay_us(50); while( ( PIND&0X1C) != 0X1C); /* exit when key released */ } else if(a==0x14) /* Accesed when the 2nd key is pressed */ { Data('2'); _delay_us(50); while( ( PIND&0X1C) != 0X1C); /* exit when key released */ } else if(a==0X0C) /* Accesed when the 3rd key is pressed */ { Data('3'); _delay_us(50); while( ( PIND&0X1C) != 0X1C); /* exit when key released */ } } } } /********************************************************************************* * Function : Command * * * * Description : Function to send a command to LCD * * * * Parameters : cmd - command to be sent * **********************************************************************************/ void Command(unsigned char cmd) { PORTD |= 0X40; /* contol line RS-0(cmd register), R/W-GND(write),E-1(enable) */ PORTB = cmd; /* command loaded to data port */ _delay_us(50); /* Minimun Delay For Hold On Data */ PORTD = 0X00; /* contol line RS-0(cmd register), R/W-GND(write),E-0(enable) */ } /********************************************************************************* * Function : Data * * * * Description : Function to display single character on LCD * * * * Parameters : dat - character to be displayed * **********************************************************************************/ void Data(unsigned char dat) { PORTD |= 0X60; /* contol line RS-1(data register), R/W - GND(write), E-1(enable) */ PORTB=dat; /* data loaded to data port */ _delay_us(50); /* Minimun Delay For Hold On Data */ PORTD = 0X00; /* contol line RS-0(data register), R/W - GND(write), E-0(enable) */ } /********************************************************************************* * Function : Display * * * * Description : Function to display string on LCD * * * * Parameters : loc - location * * LCD - String to be displayed * **********************************************************************************/ void Display(char loc, const char *LCD) { Command(loc); /* Address of location to display data */ while(*LCD!='\0') /* Check for termination character */ { Data(*LCD); /* Display the character on LCD */ LCD++; /* Increment the pointer */ } } /********************************************************************************* END OF PROGRAM **********************************************************************************/ |
Topics related to AVR ATmega16 Mini Development Board
- AVR ATmega16 Mini Development Board – Overview
- AVR ATmega16 Mini Development Board – Interfacing LED
- AVR ATmega16 Mini Development Board – Interfacing LCD
- AVR ATmega16 Mini Development Board – Serial communication(USART)
- AVR ATmega16 Mini Development Board – Interfacing Switch
- AVR ATmega16 Mini Development Board – Interfacing Buzzer
- AVR ATmega16 Mini Development Board – Interfacing POT(ADC)
- AVR ATmega16 Mini Development Board – Interfacing Temperature sensor
- AVR ATmega16 Mini Development Board – Interfacing Servo Motor
- AVR ATmega16 Mini Development Board – Interfacing μRFID
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