RS232 #use rs232(baud=9600,xmit=PIN_C6,rcv=PIN_C7 BAUD=x; Set baud rate to x units bits/sec XMIT=pin ; Set transmit pin RCV=pin; Set receive pin printf("%u",value); the printf command is used to write data to serial port.

RS232 RS232 receive data available, at the receiver pin , for example for PIC16F877 at pin RC7. value = getc(), value = fgetc(stream), value=getch(), value=getchar() This function waits for a character to come in over the RS232 RCV pin and returns the character.

Example This example receives data and resends it via RS232

Continue ADC The A/D converter module has the following features: The converter generates a 10-bit binary result (or 8-bit) using the method of successive approximation and stores the conversion results into the ADC registers (ADRESL and ADRESH); The A/D converter converts an analog input signal into a 10-bit binary number (or 8-bit); The minimum resolution or quality of conversion may be adjusted to various needs by selecting voltage references Vref- and Vref+.

Continue ADC

To select the Vref- and Vref+: Choose Constants used in SETUP_ADC_PORTS(): Example: (AN0_VREF_VREF) // A0 VRefh=A3 VRefl=A2 (AN0_AN1_AN2_AN4_VSS_VREF)// A0 A1 A2 A5 VRefh=A3

Continue ADC To select the number of bits which read_adc() returns use: #Device ADC=10 ADC=x Where x is the number of bits read_adc() should return If we use PIC16f877 x could be 8 or 10 Bits.

Interrupts Three simple steps: First: Enable Interrupts Global: enable_interrupts(GLOBAL);//tells the PIC that we are going to use interrupt Second: Enable the Specific type of Interrupt you want to use: enable_interrupts(INT_xxx);//specify the type of interrupt. See the devices .h file for all valid interrupts for the part

Interrupts Third: Write the Interrupt Subroutine: This function is executed when the interrupt occurs. The subroutine is written outside the Main loop. The function should be written directly after #Int_xxx The name of subroutine should refer to the action taken.

#Int_xxx These directives specify the following function is an interrupt function. #INT_EXT //External interrupt #INT_RB //Port B any change on B4-B7

Example Using INT_RB The following example shows how to use INT_RB. The Microcontroller is reading analog signal from analog channel one, but if a change occurred at pin RB4 (Low to High or High to Low) an Interrupt occurs and the microcontroller is programmed to light a LED at Pin RB2 and a Motor is on at pins RB0, RB1.

Practically Don't forget to connect the oscillator and power. Note: Practically the motor is not simply connected as shown. (it needs a driver circuit between MC and the motor it self). Practically Don't forget to connect the oscillator and power.

#include <16f877.h> #fuses hs,nowdt #use delay (clock=20000000) #use rs232 (baud=9600,xmit=pin_c6,rcv=pin_c7) #int_Rb //Interrupt Subroutine (Motor on Clock Wise and LED On/Off five times) Rb_isr() { int i; output_high(pin_b0); output_low(pin_b1); for ( i=1;i<=5;i++) {output_high(pin_b2); delay_ms(500); output_low(pin_b2); delay_ms(500);} output_low(pin_b0); output_low(pin_b1);}

Cont. code void main() {int value; enable_interrupts(INT_Rb); enable_interrupts(GLOBAL); setup_adc( ADC_CLOCK_INTERNAL ); setup_adc_ports( ALL_ANALOG ); while (1) { set_adc_channel(1); value= read_adc(); printf("A/D value = %u\n\r",value);}}

Other Interrupts INT_EXT //External interrupt INT_RDA //RS232 receive data available INT_TIMERx //Timer x overflow

INT_EXT Change at pin RB0 Also requires specifying the edge change using: EXT_INT_EDGE( ) Determines when the external interrupt is acted upon. The edge may be L_TO_H or H_TO_L to specify the rising or falling edge Example: ext_int_edge( H_TO_L ); // Sets up EXT This is written after enabling the interrupts (In the main loop)

INT_RDA Rather than waiting serial data to be received from the Rx pin, give this job to a specialist which is INT_RDA. If data is available at the receiver pin an Interrupt occurs.

Example The First PIC transmit data to be received by the second PIC. see the figure next slide. Receive the data using Interrupt RDA.

Transmitter Code #include <16f877a.h> #fuses xt,nowdt #use delay(clock=4000000) #users232(baud=9600,xmit=pin_c6,rcv=pin_c7) void main(){ while(1){ printf("HIJJAWI "); delay_ms(500); }}

Receiver Code #include<16f877a.h> #fuses xt,nowdt #use delay(clock=4000000) #include<lcd.c> #use rs232(baud=9600,xmit=PIN_c6,rcv=PIN_c7) char Rx[50]; int i=0; #int_RDA RDA_isr() {Rx[i++]=getch();} void main() {enable_interrupts(INT_RDA); enable_interrupts(GLOBAL); lcd_init(); while(1) {lcd_putc('\f'); lcd_gotoxy(1,1); printf(lcd_putc,"%s",Rx);}}

INT_TIMERx To deal with timers you must know the following simple commands: value=get_timer0() //Returns the count value of a real time clock/counter. RTCC and Timer0 are the same. All timers count up. When a timer reaches the maximum value it will flip over to 0 and continue counting (254, 255, 0, 1, 2...). set_timer0(value)// Sets the count value of a real time clock/counter.

INT_TIMERx // 20 mhz clock, no prescaler, set timer 0 // to overflow in 35us set_timer0(81);     // 256-(.000035/(4/20000000))