8. Microcontroller Textbook Programming Robot Controllers, Myke Predko, McGraw Hill. Reference PIC Robotics: A Beginner's Guide to Robotics Projects Using the PIC Micro, John Iovine, McGraw Hill. Embedded C Programming and the Microchip PIC, Richard H. Barnet, Delmar Learning. PIC Microcontroller: An Introduction to Software & Hardware Interfacing, Han-Way Huang, Delmar Learning. MCU 2 / page Page
Microchip PICmicroMicrocontroller MCU 2 / page 2 Page 2
Microchip PICmicroMicrocontroller Also known as PIC Advantages: Easy to find parts from numerous distributors Many version of PIC function, size, package, I/O Free IDE tools e.g. MPLAB Free C compiler mikroelektronika mikroc (limited to 2K program) HI-TECH PICC Lite(limited to 6F84 and 6F627) Microchip / BurnonMPLAB C8 (time limited) MCU 2 / page 3 Page 3
PIC Experimental Board MCU 2 / page 4 Page 4
Basic Circuit Requirements Stable +5V supply Reset line input (MCLR) Clock Internal Resistor/capacitor (RC) Crystal oscillator MCU 2 / page 5 Page 5
Pin assignment PIC 6F627 MCU 2 / page 6 PIC6F62X PINOUT DESCRIPTION RA/AN RA Bi-directional I/O port AN Analog comparator input RA/AN RA Bi-directional I/O port AN Analog comparator input RA2/AN2/VREF RA2 Bi-directional I/O port AN2 Analog comparator input VREF AN VREF output RA3/AN3/CMP RA3 Bi-directional I/O port AN3 Analog comparator input CMP Comparator output RA4/TCKI/CMP2 RA4 Bi-directional I/O port TCKI Timer clock input CMP2 OD Comparator 2 output RA5/MCLR/VPP RA5 Input port MCLR Master clear VPP Programming voltage input. When configured as MCLR, this pin isan active low RESET to the device. Voltage on MCLR/VPP must not exceed VDD during normal device operation. RA6/OSC2/CLKOUT RA6 Bi-directional I/O port OSC2 XTAL Oscillator crystal output. Connects to crystal or resonator in Crystal Oscillator mode. CLKOUT In ER/INTRC mode, OSC2 pin can output CLKOUT, which has /4 thefrequency of OSC RA7/OSC/CLKIN RA7 Bi-directional I/O port OSC XTAL Oscillator crystal input CLKIN External clock source input. ER biasing pin. RB/INT RB Bi-directional I/O port. INT External interrupt. RB/RX/DT RB Bi-directional I/O port. RX USART receive pin DT Synchronous data I/O. RB2/TX/CK RB2 Bi-directional I/O port. TX USART transmit pin CK Synchronous clock I/O. RB3/CCP RB3 Bi-directional I/O port. CCP Capture/Compare/PWM I/O RB4/PGM RB4 Bi-directional I/O port. PGM Low voltage programming input pin. RB5 RB5 Bi-directional I/O port. RB6/TOSO/TCKI/PGC RB6 Bi-directional I/O port. TOSO XTAL Timer oscillator output. TCKI ST Timer clock input. PGC ST ICSP Programming Clock. RB7/TOSI/PGD RB7 Bi-directional I/O port. TOSI XTAL Timer oscillator input. Wake-up from SLEEP on pin change. PGD ST CMOS ICSP Data I/O Page 6
Block Diagram MCU 2 / page 7 Block diagram The PIC6F62X devices contain an 8-bit ALU and working register. The ALU is a general purpose arithmetic unit. It performs arithmetic and Boolean functions between data in the working register and any register file. Depending on the instruction executed, the ALU may affect the values of the Carry (C), Digit Carry (DC), and Zero (Z) bits in the STATUS register. The C and DC bits operate as a Borrow and Digit Borrow out bit, respectively, bit in subtraction. Two types of data memory are provided on the PIC6F62X devices. Non-volatile EEPROM data memory is provided for long term storage of data such as calibration values, lookup table data, and any other data which may require periodic updating in the field. This data is not lost when power is removed. The other data memory provided is regular RAM data memory. Regular RAM data memory is provided for temporary storage of data during normal operation. It is lost when power is removed. Page 7
Configuration Register Give the application developer flexibility in how the PIC are used in application. If register are not set correctly, PIC will not run properly. Register is written when the PIC is being programmed. Register content is accessed in PIC bootup process to select the hardware options required for application. MCU 2 / page 8 Configuration register define for: [details refer to textbook Table3-5] Code / data protection (CP / CPD) -normally set OFF Low voltage programming (LVP) -normally set disable Brown-out detect (BODEN) -normally set enable Reset parameters (MCLR) use _MCLR as reset pin Power-up timer -normally set enable Watchdog timer (WDT) -normally set disable Oscillator mode used (FOSC-2) normally set HS (high speed) For mikroc, default setting is: Oscillator mode = HS WDT = disable LVP = disable Page 8
Input/Output (I/O) Registers TRISx(where x = A or B) To control the input/output of the I/O pin Register load with, I/O pin set as input Register load with, I/O pin set as output e.g. TRISA.F = will set port A pin (i.e. RA) as input TRISB.F7 = will set port B pin 7 (i.e. RB7) as output PORTx(where x = A or B) Directly store data sending out or received from I/O pin e.g. PORTA.F = will send high to port A pin (RA) temp = PORTB.F3 will assign data received from port B pin3 (RB3) to temp MCU 2 / page 9 I/O convention for mikroc and PICC-Lite: mikroc TRISA TRISA.F PORTB PORTB.F PICC-Lite TRISA TRISA PORTB or RB PORTB. or PORTB or RB Page 9
Input/Output Registers How to make RB2 I/O pin a digital output and drive a high value? TRISB.F2 = ; // RB2 set as output pin PORTB.F2 = ; // RB2 drives a high value out How to make RA I/O pin a digital output and drive a low value? TRISA.F = ; // RA set as output pin PORTA.F = ; // RA drives a low value out How to make RA7 I/O pin a digital input and receive a data? TRIS.F = ; // RA7 set as input pin temp = PORT.F ; // Receive from RA7 and assign to temp MCU 2 / page Page
Input/Output Registers How to drive entire Port B to high values? TRISB = ; PORTB = xff; How to make RA I/O pin digital inputs and store the received data to temp? TRISA = x ; temp = ; MCU 2 / page Page
Workshop mikrocstartup and burn PIC LED flashing void main() { PORTB = ; TRISB = ; while() { PORTB = ~PORTB; Delay_ms(); MCU 2 / page 2 Page 2
Workshop 2 -PIC input and output void main() { PORTB = ; TRISB = ; CMCON = x7; /* enable digital I/O for PORTA */ TRISA.F = ; /* set RA as input */ while() { if (PORTA.F) PORTB = xff; else PORTB = ; Delay_ms(); /* set ms delay */ MCU 2 / page 3 Page 3
Page 4 Hong Kong Institute of Vocational Education Hong Kong Institute of Vocational Education MCU 2 / page 4 7-segment LED display 8 e 4 48 98 c 24 9e 2 value 9 8 7 6 5 4 3 2 dp g f e d c b a Char
Workshop 3 -PIC output to 7-segment display void main() { PORTB = ; TRISB = ; while() { PORTB = x2; /**/ Delay_ms(); PORTB = x9e; /**/ Delay_ms(); PORTB = x24; /*2*/ Delay_ms(); PORTB = xc; /*3*/ Delay_ms(); PORTB = x98; /*4*/ Delay_ms(); PORTB = x48; /*5*/ Delay_ms(); PORTB = x4; /*6*/ Delay_ms(); PORTB = xe; /*7*/ Delay_ms(); PORTB = x; /*8*/ Delay_ms(); PORTB = x8; /*9*/ Delay_ms(); MCU 2 / page 5 Page 5
Workshop 4 -PIC interactive I/O void main() { int seg7[] = {x2, x9e, x24, xc, x98, x48, x4, xe, x, x8; /* to 9*/ int index = ; /* for store the current display digit */ PORTB = seg7[]; TRISB = ; CMCON = x7; /* enable digital I/O for PORTA */ TRISA.F = ; TRISA.F = ; while () { if (PORTA.F = = ) /* when RA is pressed */ { index = index + ; if (index == ) index = ; PORTB = seg7[index]; Delay_ms(); MCU 2 / page 6 Page 6
Workshop 5 -PIC input decode void main() { int seg7[] = {x2, x9e, x24, xc, x98, x48, x4, xe, x, x8; /* to 9*/ int index = ; /* for store the current display digit */ PORTB = seg7[]; TRISB = ; CMCON = x7; /* enable digital I/O for PORTA */ TRISA.F = ; /* set all 4 inputs for PORTA */ TRISA.F = ; TRISA.F2 = ; TRISA.F3 = ; while () { index = ; if (PORTA.F == ) index = index + ; /* calculate weighting */ if (PORTA.F == ) index = index + 2; if (PORTA.F2 == ) index = index + 4; if (PORTA.F3 == ) index = index + 8; if (index > 9) /* Display to 9 */ index = ; PORTB = seg7[index]; Delay_ms(); MCU 2 / page 7 Page 7
Music Frequency Tone do re me fa so la ti Frequency 46.5 74.7 38.5 396.9 568 76 975.5 Period / 2 478 426 379 358 39 284 253 MCU 2 / page 8 Page 8
Workshop 6 -PIC output to speaker void main() { int i; PORTB = xff; TRISB = ; CMCON = x7; /* enable digital I/O for PORTA */ TRISA.F = ; TRISA.F = ; TRISA.F2 = ; TRISA.F3 = ; while () { if (PORTA.F == ) { for (i=; i<5; i++) { PORTB.F = ; Delay_us(478); /* do */ PORTB.F = ; Delay_us(478); MCU 2 / page 9 Page 9
Interrupt setting void main() { TRISB = x; /* RB as interrupt */ INTCON.GIE = ; /* enable global interrupt */ INTCON.INTE = ; /* enable RB/INT pin interrupt */ while() { void interrupt () { INTCON.INTE = ; /* disable interrupt avoid interrupt again */ if (INTCON.INTF) { /* check interrupt from RB */ INTCON.INTF = ; /* reset interrupt flag */ INTCON.INTE = ; /* enable interrupt again */ MCU 2 / page 2 Page 2
Workshop 7 -PIC interrupt void interrupt () { int i, j; INTCON.INTE = ; if (INTCON.INTF) { PORTB = x55; Delay_ms(); PORTB = xaa; Delay_ms(); PORTB = x55; Delay_ms(); PORTB = xaa; Delay_ms(); INTCON.INTF = ; /* reset interrupt flag */ PORTB = ; /* reset pattern */ INTCON.INTE = ; void main() { PORTB = ; TRISB = x; /* RB as interrupt */ INTCON.GIE = ; /* enable global interrupt */ INTCON.INTE = ; /* enable RB/INT pin interrupt */ while() { PORTB = ~PORTB; Delay_ms(); MCU 2 / page 2 Page 2
Baud Rate Generator In Asynchronous mode bit Baud Rate Generator controls the baud rate. Given the desired baud rate and Fosc, the nearest integer value for the SPBRG register can be calculated using the following formula: When BRGH =, SYNC =, Desired Baud rate = Fosc/ (64 (X + )) Fosc= 6 MHz, Desired Baud Rate = 96 96 = 6 / (64(X+ )) X = 25.42 Calculated Baud Rate = 6 / (64(25 + )) = 965 Error = (Calculated Baud Rate -Desired Baud Rate) / Desired Baud Rate = (965-96)/ 96 =.6% MCU 2 / page 22 Page 22
Workshop 8 -Serial Comm. void main() { unsigned char temp; OPTION_REG = xd; /* assign prescalar to TMR */ TMR = ; /* reset timer for start */ INTCON.TIE = ; /* enable timer interrupt */ INTCON.GIE = ; /* enable global interrupt */ SPBRG = 2; /* 5 : baud rate = 2 @ 4MHz */ /* 2 : baud rate = 48 */ TXSTA.TXEN = ; /* enable usart */ RCSTA.CREN = ; /* enable continuous receive*/ RCSTA.SPEN = ; /* serial port enable */ PIR.RCIF = ; /* clear receive flag */ while () { if (PIR.RCIF) { /* wait char received */ temp = RCREG; /* get char */ TXREG = temp -; /* modify char */ PIR.RCIF = ; /* clear flag */ MCU 2 / page 23 Page 23
L293 Motor Driver MCU 2 / page 24 Page 24
Workshop 9 -Motor control void main() { PORTB = ; TRISB.F5 = ; /* motor enable */ TRISB.F6 = ; /* motor direction */ TRISB.F7 = ; /* RB6, RB7 =, or, = no motion */ /*, one direction */ /*, other direction */ CMCON = x7; /* enable digital I/O for PORTA */ TRISA.F = ; TRISA.F = ; PORTB.F5 = ; /* enable motor */ while () { if (PORTA.F == ) { /* RA press */ PORTB.F6 = ; PORTB.F7 = ; Delay_ms(); if (PORTA.F == ) { /* RA press */ PORTB.F6 = ; PORTB.F7 = ; Delay_ms(); PORTB.F6 = ; PORTB.F7 = ; MCU 2 / page 25 Page 25