Monday, April 4, 2016

DC motor control with PIC16F84A and L293D

Low power DC motors can be easily controlled with half H-bridge IC L293D. This IC is 16-pin IC which can control 2 motors in both directions.
This topic shows how to control DC motor speed and direction with PIC16F84A and L293D motor drive integrated circuit.
Related topics:
The following topic shows how to control a DC motor with PIC16F84A and H-bridge circuit.
DC Motor speed and direction control with PIC16F84A using H-bridge

DC motor control with PIC16F84A and L293D circuit:
Project circuit schematic is shown below
DC motor speed/direction control using PIC16F84A and L293D CCS PIC C
The nominal voltage of the motor is 12V as well as L293D VS input voltage. Always L293D VS voltage is the same as the DC motor voltage and L293D VSS voltage is +5V.
In the circuit there are 5 buttons, the first button which is connected to RB0 pin is used to speed up the motor, and speed down button to decrease motor speed. Third and fourth buttons are used to choose direction rotation of the motor (direction 1 or direction 2). The last button stops the motor no matter what speed or direction.
There are 3 LEDs, LED1 and LED2 are used to indicate motor direction, and the other LED indicates maximum speed, which means when it is on the motor is running at maximum speed.
When speed up button is pressed the PWM duty cycle increases which causes the motor to increase its speed and when the duty cycle = 100 LED 3 turned on. In the other hand if speed down button is pressed the duty cycle decreases and the motor speed also decreases.
If the stop button pressed the motor stops and the 3 LEDs are off.
Software PWM is used wih frequency of 500Hz.
DC Motor control with PIC16F84A and L293D CCS C code:
The full C code is shown below. Official software PWM library which comes with CCS PIC C compiler is used, this library uses Timer0 to generate the PWM signal.
// DC motor control using PIC16F84A and L293D CCS C code
// http://ccspicc.blogspot.com/
// electronnote@gmail.com

#include <16F84A.h>
#fuses HS,NOWDT,PUT,NOPROTECT
#use delay(clock = 8000000)
#use fast_io(A)
#use fast_io(B)
#use pwm(output = pin_a0, output = pin_a1, timer = 0, frequency= 500Hz, duty = 0)

unsigned int8 i = 1;
void main() {
  port_b_pullups(TRUE);                // Enable PORTB pull-ups
  output_a(0);                         // PORTA initial state
  set_tris_a(0);                       // All PORTA pins are configured as outputs
  output_b(0);                         // PORTB initial state
  set_tris_b(0x1F);                    // Configure RB0 to RB4 as inputs
  pwm_off();                           // Turn off all pwm outputs
  while(TRUE) {
    if(input(PIN_B0) == 0){            // If RB0 button pressed
      i++;                             // Increment i by 1 (i = i + 1)
      if(i > 99){
        i = 100;
        output_high(PIN_B7);}          // RB7 LED ON
      pwm_set_duty_percent(i * 10UL);  // Duty cycle change in tenths %
      delay_ms(100);      }            // Wait 100ms
    if(input(PIN_B1) == 0){            // If RB1 button pressed
      output_low(PIN_B7);              // RB7 LED OFF
      i--;                             // Decrement i by 1 (i = i - 1)
      if(i < 1)
        i = 1;
      pwm_set_duty_percent(i * 10UL);  // Duty cycle change in tenths %
      delay_ms(100);      }            // Wait 100ms
    if(input(PIN_B2) == 0){            // If RB2 button pressed
      if(input(PIN_B5) == 0){
        output_low(PIN_B6);            // RB6 LED OFF
        pwm_off();                     // Turn off pwm for both outputs
        output_a(0);                   // PORTA pins low
        delay_ms(100);                 // Wait 100ms
        pwm_on(PIN_A0);                // Turn pwm on at RA0
        output_high(PIN_B5);           // RB5 LED ON
        if(i > 99)
          output_high(PIN_B7);}}
    if(input(PIN_B3) == 0){            // If RB3 button pressed
      if(input(PIN_B6) == 0){
        output_low(PIN_B5);            // RB5 LED OFF
        pwm_off();                     // Turn off pwm for both outputs
        output_a(0);                   // PORTA pins low
        delay_ms(100);                 // Wait 100ms
        pwm_on(PIN_A1);                // Turn PWM on at RA1
        output_high(PIN_B6);
        if(i > 99)
          output_high(PIN_B7);}}
    if(input(PIN_B4) == 0){            // If RB4 button pressed
      pwm_off();                       // Turn off pwm for both outputs
      output_a(0);                     // PORTA pins low
      output_b(0);}                    // PORTB pins low
    }
}



DC Motor control with PIC16F84A and L293D video:
The following video shows a hardware circuit of the project.

Sunday, April 3, 2016

RC-5 remote control decoder with PIC18F4550 and CCS C

PIC18F4550 RC-5 decoder
The RC-5 protocol was developed by Philips in the late 1980s as a semi-proprietary consumer IR (infrared) remote control communication protocol for consumer electronics.
The RC5 has 14 bits per 1 code transmission, the 14 bits can be divided into 4 parts:

The first 2 bits are start bits and they are always logic 1.
The third bit called toggle bit, it can be logic 1 or logic 0.
The next 5 bits are address bits, each device type has its address number for example TV address number is 0, CD player address = 20 ............
And the last 6 bits are command bits, each button has its command number.
For the same device for example TV all the remote control buttons has the same address but each button has its command.
The toggle bit changes whenever a button is pressed.
The RC5 protocol uses Manchester coding, logic 1 and logic 0 are coded as shown in the following drawing where toggle bit is 1, address = 0 and command is 2: 
RC5 IR remote control protocol coding 
This link from Wikipedia has more details about Philips RC5 protocol.
RC5 IR remote control protocol decoder using PIC18F4550 microcontroller: This topic shows how to decode and get RC5 data of a TV remote control uses RC5 protocol with PIC18F4550 microcontroller and CCS PIC C compiler.
The project circuit schematic is shown below.
 RC5 IR remote control protocol decoder with PIC18F4550 microcontroller circuit schematic CCS PIC C
The IR receiver is used to receive the IR signals transmitted from the remote control and convert this signals to a digital data (logic 0, logic 1). The microcontroller PIC18F4550 reads digital data from the IR receiver, this data is decoded and the results displayed on 1602 LCD display. The LED which is connected to RB1 pin blinks when RC5 protocol is received.
The following drawing shows how the IR receiver receive and transmit data to the microcontroller:
IR receiver circuit 
RC5 IR remote control protocol decoder using PIC18F4550 CCS PIC C code:
The code is written and compiled with CCS C compiler.
I made the code simple as I can, no Timer module and no interrupt are used.
The microcontroller waits until the IR receiver receives IR data which means it waits until RB0 pin goes from high to low.
The 2 start bits are used to check if the received IR signal uses RC5 protocol. Each bit is 1778us long. The fist start bit is 1 which means it is 0 for 889us and 1 for 889us, the first 889us is not detected because RB0 not triggered yet and the second 889us is detected using the following code:
while((input(PIN_B0) == 0) && (count < 20)){
  count++;
  delay_us(50);}
  if( (count > 20) || (count < 14))

    goto ret;
The signal is checked every 50us and a variable (count) is used to count number of 50s, for example if count = 5 so the total time before RB0 goes high is 250us.
If count >= 20 it means time out and the received signal is high for more than 889us.
If count < 14 it means signal high time is lower than 889us.
The second start bit is checked using the following code:
// Check first 889us
while((input(PIN_B0)) && (count < 20)){
   count++;
    delay_us(50);}
    if( (count > 20) || (count < 14))            

      goto ret;
// Check 2nd 889us
      count = 0;
while((input(PIN_B0) == 0) && (count < 40)){
  count++;
  delay_us(50);}
  if( (count > 40) || (count < 14))      // Signal doesn't use RC5 protocol
    goto ret;                           
  if(count > 30)
    delay_us(400);
  else          
    delay_us(1200);

Second bit checking is the same as the first bit checking except that low both 889us are checked.
After the 2nd start bit there is toggle bit which is 1 or 0, and if toggle bit is 0 time required for RB0 pin is 1778us which means to start reading bits we have to add a delay about 400us, and if the toggle bit is 1 we have to wait 1200us.
The following drawing shows the 2 start bit with toggle bit when it's 0 and when it's 1:
RC-5 IR remote control code
And the following drawing shows when the microcontroller reads the RC5 bits:
RC5 IR remote control decoding
The complete RC5 decoder CCS C code is as the following below.
// RC5 remote control protocol decoder with PIC18F4550 CCS C code
// http://ccspicc.blogspot.com/
// electronnote@gmail.com

//LCD module connections
#define LCD_RS_PIN PIN_D0
#define LCD_RW_PIN PIN_D1
#define LCD_ENABLE_PIN PIN_D2
#define LCD_DATA4 PIN_D3
#define LCD_DATA5 PIN_D4
#define LCD_DATA6 PIN_D5
#define LCD_DATA7 PIN_D6
//End LCD module connections

#include <18F4550.h>
#fuses NOMCLR INTRC_IO
#use delay(clock = 8000000)
#include <lcd.c>
#use fast_io(B)

int1 toggle;
unsigned int8 count, i, address, command;
void main(){
  setup_oscillator(OSC_8MHZ);            // Set internal oscillator to 8MHz
  port_b_pullups(TRUE);                  // Enable PORTB pull-ups
  output_b(0);                           // PORTB initial state
  set_tris_b(1);
  lcd_init();                            // Initialize LCD module
  lcd_putc('\f');                        // LCD clear
  lcd_gotoxy(3, 1);                      // Go to column 3 row 1
  lcd_putc("RC5 protocol");
  lcd_gotoxy(5, 2);                      // Go to column 5 row 2
  lcd_putc("decoder");
  while(TRUE){
    ret:
    count = 0;
    output_low(PIN_B1);
    while(input(PIN_B0));                // Wait until RB0 pin falls
    // Check if the received signal uses RC5 protocol
    while((input(PIN_B0) == 0) && (count < 20)){
      count++;
      delay_us(50);}
    if( (count > 20) || (count < 14))      // Signal doesn't use RC5 protocol
      goto ret;                            // Return
    count = 0;
    while((input(PIN_B0)) && (count < 20)){
      count++;
      delay_us(50);}
    if( (count > 20) || (count < 14))      // Signal doesn't use RC5 protocol
      goto ret;                            // Return
    count = 0;
    while((input(PIN_B0) == 0) && (count < 40)){
      count++;
      delay_us(50);}
    if( (count > 40) || (count < 14))      // Signal doesn't use RC5 protocol
      goto ret;                            // Return
    // End check (The received signal uses RC5 protocol)
    if(count > 30)
      delay_us(400);
    else
      delay_us(1300);
    output_high(PIN_B1);                        // Toggle RB1 LED
    for(i = 0; i < 12; i++){
      if(i == 0){
        if(input(PIN_B0) == 1)   toggle = 0;
        else                     toggle = 1;
        }
      else {
        if(i < 6){                                //Read address bits
          if(input(PIN_B0) == 1)
            bit_clear(address, (5 - i));          //Clear bit (5-i)
          else
            bit_set(address, (5 - i));           //Set bit (5-i)
          }
        else {                                 //Read command bits
          if(input(PIN_B0) == 1)
            bit_clear(command, (11 - i));        //Clear bit (11-i)
          else
            bit_set(command, (11 - i));          //Set bit (11-i)
          }
        }
      delay_us(1778);
      }
                     // Display results
    address &= 0x1F;
    command &= 0x3F;
    lcd_putc('\f');
    lcd_gotoxy(2, 1);
    lcd_putc("Toggle bit:");
    lcd_gotoxy(1, 2);
    lcd_putc("Adds:");
    lcd_gotoxy(9, 2);
    lcd_putc("Cmd:");
    lcd_gotoxy(14, 1);
    printf(lcd_putc,"%1u",toggle);
    lcd_gotoxy(6, 2);
    printf(lcd_putc,"%2u",address);
    lcd_gotoxy(14, 2);
    printf(lcd_putc,"%2u",command);
    }
}

RC5 IR remote control protocol decoder using PIC18F4550 video:
The following video shows the project using hardware circuit with some details.

Saturday, April 2, 2016

RC5 IR remote control decoder with PIC16F84A and CCS PIC C

PIC16F84A RC-5 decoder
The RC-5 protocol was developed by Philips in the late 1980s as a semi-proprietary consumer IR (infrared) remote control communication protocol for consumer electronics.
The RC5 has 14 bits per 1 code transmission, the 14 bits can be divided into 4 parts:

The first 2 bits are start bits and they are always logic 1.
The third bit called toggle bit, it can be logic 1 or logic 0.
The next 5 bits are address bits, each device type has its address number for example TV address number is 0, CD player address = 20 ............
And the last 6 bits are command bits, each button has its command number.
For the same device for example TV all the remote control buttons has the same address but each button has its command.
The toggle bit changes whenever a button is pressed.
The RC5 protocol uses Manchester coding, logic 1 and logic 0 are coded as shown in the following drawing where toggle bit is 1, address = 0 and command is 2: 
RC5 IR remote control protocol coding 
This link from Wikipedia has more details about Philips RC5 protocol.
RC5 IR remote control protocol decoder using PIC16F84A microcontroller: This topic shows how to decode and get RC5 data of a TV remote control uses RC5 protocol with PIC16F84A microcontroller and CCS PIC C compiler.
The project circuit schematic is shown below.
RC-5 IR remote control decoder using PIC16F84A microcontroller circuit schematic CCS PIC C 
The IR receiver is used to receive the IR signals transmitted from the remote control and convert this signals to a digital data (logic 0, logic 1). The microcontroller PIC16F84A reads digital data from the IR receiver, this data is decoded and the results displayed on 1602 LCD display. The LED which is connected to RB1 pin blinks when RC5 protocol is received.
The following drawing shows how the IR receiver receive and transmit data to the microcontroller:
IR receiver circuit 
RC5 IR remote control protocol decoder using PIC16F84A CCS PIC C code:
The code is written and compiled with CCS C compiler.
I made the code simple as I can, no Timer module and no interrupt are used.
The microcontroller waits until the IR receiver receives IR data which means it waits until RB0 pin goes from high to low.
The 2 start bits are used to check if the received IR signal uses RC5 protocol. Each bit is 1778us long. The fist start bit is 1 which means it is 0 for 889us and 1 for 889us, the first 889us is not detected because RB0 not triggered yet and the second 889us is detected using the following code:
while((input(PIN_B0) == 0) && (count < 20)){
  count++;
  delay_us(50);}
  if( (count > 20) || (count < 14))

    goto ret;
The signal is checked every 50us and a variable (count) is used to count number of 50s, for example if count = 5 so the total time before RB0 goes high is 250us.
If count >= 20 it means time out and the received signal is high for more than 889us.
If count < 14 it means signal high time is lower than 889us.
The second start bit is checked using the following code:
// Check first 889us
while((input(PIN_B0)) && (count < 20)){
   count++;
    delay_us(50);}
    if( (count > 20) || (count < 14))            

      goto ret;
// Check 2nd 889us
      count = 0;
while((input(PIN_B0) == 0) && (count < 40)){
  count++;
  delay_us(50);}
  if( (count > 40) || (count < 14))      // Signal doesn't use RC5 protocol
    goto ret;                           
  if(count > 30)
    delay_us(400);
  else          
    delay_us(1300);

Second bit checking is the same as the first bit checking except that low both 889us are checked.
After the 2nd start bit there is toggle bit which is 1 or 0, and if toggle bit is 0 time required for RB0 pin is 1778us which means to start reading bits we have to add a delay about 400us, and if the toggle bit is 1 we have to wait 1200us.
The following drawing shows the 2 start bit with toggle bit when it's 0 and when it's 1:
RC-5 IR remote control code
And the following drawing shows when the microcontroller reads the RC5 bits:
RC5 IR remote control decoding
The complete RC5 decoder CCS C code is as the following below.
// Philips RC5 IR remote control decoder using PIC16F84A CCS C code
// http://ccspicc.blogspot.com/
// electronnote@gmail.com

//LCD module connections
#define LCD_RS_PIN PIN_B1
#define LCD_RW_PIN PIN_B2
#define LCD_ENABLE_PIN PIN_B3
#define LCD_DATA4 PIN_B4
#define LCD_DATA5 PIN_B5
#define LCD_DATA6 PIN_B6
#define LCD_DATA7 PIN_B7
//End LCD module connections

#include <16F84A.h>
#fuses HS,NOWDT,PUT,NOPROTECT
#use delay(crystal=8000000)
#include <lcd.c>
#use fast_io(B)

int1 toggle;
unsigned int8 count, i, address, command;
void main(){
  port_b_pullups(TRUE);                  // Enable PORTB pull-ups
  output_b(0);                           // PORTB initial state
  set_tris_b(1);
  lcd_init();                            // Initialize LCD module
  lcd_putc('\f');                        // LCD clear
  lcd_gotoxy(3, 1);                      // Go to column 3 row 1
  lcd_putc("RC5 protocol");
  lcd_gotoxy(5, 2);                      // Go to column 5 row 2
  lcd_putc("decoder");
  while(TRUE){
    ret:
    count = 0;
    while(input(PIN_B0));                // Wait until RB0 pin falls
    // Check if the received signal uses RC5 protocol
    while((input(PIN_B0) == 0) && (count < 20)){
      count++;
      delay_us(50);}
    if( (count > 20) || (count < 14))      // Signal doesn't use RC5 protocol
      goto ret;                            // Return
    count = 0;
    while((input(PIN_B0)) && (count < 20)){
      count++;
      delay_us(50);}
    if( (count > 20) || (count < 14))      // Signal doesn't use RC5 protocol
      goto ret;                            // Return
    count = 0;
    while((input(PIN_B0) == 0) && (count < 40)){
      count++;
      delay_us(50);}
    if( (count > 40) || (count < 14))      // Signal doesn't use RC5 protocol
      goto ret;                            // Return
    // End check (The received signal uses RC5 protocol)
    if(count > 30)
      delay_us(400);
    else
      delay_us(1300);
    for(i = 0; i < 12; i++){
      if(i == 0){
        if(input(PIN_B0) == 1)   toggle = 0;
        else                     toggle = 1;
        }
      else {
        if(i < 6){                                //Read address bits
          if(input(PIN_B0) == 1)
            bit_clear(address, (5 - i));          //Clear bit (5-i)
          else
            bit_set(address, (5 - i));           //Set bit (5-i)
          }
        else {                                 //Read command bits
          if(input(PIN_B0) == 1)
            bit_clear(command, (11 - i));        //Clear bit (11-i)
          else
            bit_set(command, (11 - i));          //Set bit (11-i)
          }
        }
      delay_us(1778);
      }
                     // Display results
    address &= 0x1F;
    command &= 0x3F;
    lcd_putc('\f');
    lcd_gotoxy(2, 1);
    lcd_putc("Toggle bit:");
    lcd_gotoxy(1, 2);
    lcd_putc("Adds:");
    lcd_gotoxy(9, 2);
    lcd_putc("Cmd:");
    lcd_gotoxy(14, 1);
    printf(lcd_putc,"%1u",toggle);
    lcd_gotoxy(6, 2);
    printf(lcd_putc,"%2u",address);
    lcd_gotoxy(14, 2);
    printf(lcd_putc,"%2u",command);
    }
}

RC5 IR remote control protocol decoder using PIC16F84A video:
The following video shows the project using hardware circuit with some details.