Microcontrollers session

What is Microcontroller? Microcontroller is composed of microprocessor,ram, flash memory,EEPROM and some modules like timers, Analog to Digital converter, CCP, USART, etc.… Ahmed Hussam 2

The Microprocessor:  In the PIC there is a processor that can execute only some instructions according to its type (8, 16, 32, 64 bits).  The instructions are excited by the processor in four main steps : (fetch, decode, execute, store )  The speed of the microprocessor is how many instructions can be executed in one second  The processor speed depends on the crystal oscillator frequency so by increasing the crystal frequency the speed of the processor increase Ahmed Hussam 3

Memory organization (Flash Memory) - The PIC18F has a 21-bit program counter (PC)it can address 2 Mbyte (221 locations). -PC determines the address of the instruction to fetch for execution. -The size of any instruction is 1 words excepts 4 instruction that takes 2 words. (word=2 byte) Ahmed Hussam4

Memory organization (RAM) Ahmed Hussam 5

Assembly instructions  There are 75 assembly instruction.  The most important instructions are : (MOVLW, MOVWF, MOVF, MOVFF, ADDWF, CLRF, SETF, BCF, BSF, BRA, GOTO,BTFSS, BTFSC, CPFSGT, CPFSLT, CPFSEQ, RETURN, RETFIE FAST) Ahmed Hussam6

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List of symbols used in instruction set Ahmed Hussam10

Digital input/output ports  Some pins of the I/O ports are multiplexed with an alternate function from the peripherals of the MCU.  If the PIN is enabled as I/O other function is disabled.  Each port has three registers for its operation: TRIS register: Data direction register PORT register: read the levels (1 or 0) of the pins LAT register: output latch (we clear it always once at the beginning)  Any bit in TRIS determine the direction of its corresponding bit/pin in the PORT.  If TRIS bit =1 corresponding PORT pin is Input  If TRIS bit =0 corresponding PORT pin is Output Ahmed Hussam 11

 Example: write an initializing code for PORTA to set RA4 as an O/P while the rest of pins are set as I/P.  Solution: clrf PORTA, ACCESS clrf LATA, ACCESS movlw 0XEF ; (1 Input, 0 Output) movwf TRISA, ACCESS ;set all PORTA pins are I/P except RA4 is o/p. Ahmed Hussam12

Analog to digital convertor (ADC) Ahmed Hussam13

How to use the ADC ??  There are 5 special function registers (SFR) used in the ADC MODULE IN PIC 18F4620  A/D Result High Register (ADRESH)  A/D Result Low Register (ADRESL)  A/D Control Register 0 (ADCON0)  A/D Control Register 1 (ADCON1)  A/D Control Register 2 (ADCON2) Ahmed Hussam14

bit 7-6 Unimplemented: Read as ‘0’ bit 5-2 CHS3:CHS0: Analog Channel Select bits 0000 = Channel 0 (AN0) 0001 = Channel 1 (AN1) 0010 = Channel 2 (AN2) 0011 = Channel 3 (AN3) 0100 = Channel 4 (AN4) 0101 = Channel 5 (AN5)(1,2) 0110 = Channel 6 (AN6)(1,2) 0111 = Channel 7 (AN7)(1,2) 1000 = Channel 8 (AN8) 1001 = Channel 9 (AN9) 1010 = Channel 10 (AN10) 1011 = Channel 11 (AN11) 1100 = Channel 12 (AN = Unimplemented(2) 1110 = Unimplemented(2) 1111 = Unimplemented(2) Ahmed Hussam 15

 bit 1 GO/DONE: A/D Conversion Status bit  When ADON = 1:  1 = A/D conversion in progress  0 = A/D Idle  bit 0 ADON: A/D On bit  1 = A/D converter module is enabled  0 = A/D converter module is disabled Ahmed Hussam16

bit 7-6 Unimplemented: Read as ‘0’ bit 5 VCFG1: Voltage Reference Configuration bit (VREF- source) 1 = VREF- (AN2) 0 = VSS bit 4 VCFG0: Voltage Reference Configuration bit (VREF+ source) 1 = VREF+ (AN3) 0 = VDD Ahmed Hussam17

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bit 7 ADFM: A/D Result Format Select bit 1 = Right justified 0 = Left justified bit 6 Unimplemented: Read as ‘0’ bit 5-3 ACQT2:ACQT0: A/D Acquisition Time Select bits 111 = 20 TAD 110 = 16 TAD 101 = 12 TAD 100 = 8 TAD 011 = 6 TAD 010 = 4 TAD 001 = 2 TAD 000 = 0 TAD(1) bit 2-0 ADCS2:ADCS0: A/D Conversion Clock Select bits 111 = FRC (clock derived from A/D RC oscillator)(1) 110 = FOSC/ = FOSC/ = FOSC/4 011 = FRC (clock derived from A/D RC oscillator)(1) 010 = FOSC/ = FOSC/8 000 = FOSC/2 Ahmed Hussam 19

The acquisition time bits table Ahmed Hussam20

ADC block diagram Ahmed Hussam21

Pulse width modulation (PWM)  CCP module is a module can used in one of three modes  1- Capture  2- Compare  3- PWM  PWM is used to control on the width of the pulse and its frequency  in pwm mode you must run timer 2 to determine the frequency and the pulse width  There are three SFR used to control the ccp module  1- CCP1CON  2-CCP1RL  3-CCP1RH Ahmed Hussam22

Ahmed Hussam23 bit 7-6 Unimplemented: Read as ‘0’ bit 5-4 DCxB1:DCxB0: PWM Duty Cycle bit 1 and bit 0 for CCP Module x Capture mode: Unused. Compare mode: Unused. PWM mode: These bits are the two LSbs (bit 1 and bit 0) of the 10-bit PWM duty cycle. The eight MSbs (DCx9:DCx2) of the duty cycle are found in CCPRxL. you also need two SFR in timer 2 1- T2CON 2- PR2 the pwm module in pic 18F4620 is 10 bits pwm.

 bit 3-0 CCPxM3:CCPxM0: CCP Module x Mode Select bits  0000 = Capture/Compare/PWM disabled (resets CCP module)  0001 = Reserved  0010 = Compare mode, toggle output on match (CCPIF bit is set)  0011 = Reserved  0100 = Capture mode, every falling edge  0101 = Capture mode, every rising edge  0110 = Capture mode, every 4th rising edge  0111 = Capture mode, every 16th rising edge  1000 = Compare mode: initialize CCP pin low; on compare match, force CCP pin high  (CCPxIF bit is set)  1001 = Compare mode: initialize CCP pin high; on compare match, force CCP pin low  (CCPxIF bit is set)  1010 = Compare mode: generate software interrupt on compare match (CCPxIF bit is set,  CCP pin reflects I/O state)  1011 = Compare mode: trigger special event, reset timer, start A/D conversion on  CCP2 match (CCPxIF bit is set)  11xx = PWM mode Ahmed Hussam24

Timer 2 Ahmed Hussam25 bit 7 Unimplemented: Read as ‘0’ bit 6-3 T2OUTPS3:T2OUTPS0: Timer2 Output Postscale Select bits 0000 = 1:1 Postscale 0001 = 1:2 Postscale 1111 = 1:16 Postscale bit 2 TMR2ON: Timer2 On bit 1 = Timer2 is on 0 = Timer2 is off bit 1-0 T2CKPS1:T2CKPS0: Timer2 Clock Prescale Select bits 00 = Prescaler is 1 01 = Prescaler is 4 1x = Prescaler is 16

Period and duty determination  RC2 must be initialized as output for PWM.  PWM Period = (4/Fosc) * (PR2+1) * TMR2 prescale  PWM duty cycle = (1/Fosc) * (CCPR1L:CCP1CON ) * TMR2 prescale Ahmed Hussam26

Learn more about:  Capture  Compare  EEPROM  Lock up table  Interrupt  Low voltage detector  USART  CAN (found in pic 18F458) Ahmed Hussam27

Interrupt:  PIC18F has high and low priority interrupts.  High priority interrupt vector at 0X0008  Low priority interrupt vector at 0X0018  The high priority interrupt override low priority interrupt  Each interrupt source has 3 bits to control its operation: 1. Flag bit: to indicate the occurrence of the interrupt event 2. Enable bit: to enable the interrupt (allow the PC to branch to the interrupt vector address when the flag bit is set) vector address when the flag bit is set) 3. Priority bit: to select high or low priority Interrupt priority feature is enabled by setting IPEN bit in RCON register  Interrupt priority feature is enabled by setting IPEN bit in RCON register. Ahmed Hussam 28

Ahmed Hussam29 bit 7 GIE/GIEH: Global Interrupt Enable bit When IPEN = 0: 1 = Enables all unmasked interrupts 0 = Disables all interrupts When IPEN = 1: 1 = Enables all high priority interrupts 0 = Disables all interrupts bit 6 PEIE/GIEL: Peripheral Interrupt Enable bit When IPEN = 0: 1 = Enables all unmasked peripheral interrupts 0 = Disables all peripheral interrupts When IPEN = 1: 1 = Enables all low priority peripheral interrupts 0 = Disables all low priority peripheral interrupts

 bit 5 TMR0IE: TMR0 Overflow Interrupt Enable bit  1 = Enables the TMR0 overflow interrupt  0 = Disables the TMR0 overflow interrupt  bit 4 INT0IE: INT0 External Interrupt Enable bit  1 = Enables the INT0 external interrupt  0 = Disables the INT0 external interrupt  bit 3 RBIE: RB Port Change Interrupt Enable bit  1 = Enables the RB port change interrupt  0 = Disables the RB port change interrupt  bit 2 TMR0IF: TMR0 Overflow Interrupt Flag bit  1 = TMR0 register has overflowed (must be cleared in software)  0 = TMR0 register did not overflow  bit 1 INT0IF: INT0 External Interrupt Flag bit  1 = The INT0 external interrupt occurred (must be cleared in software)  0 = The INT0 external interrupt did not occur  bit 0 RBIF: RB Port Change Interrupt Flag bit  1 = At least one of the RB7:RB4 pins changed state (must be cleared in software)  0 = None of the RB7:RB4 pins have changed state Ahmed Hussam30

Ahmed Hussam31 bit 7 RBPU: PORTB Pull-up Enable bit 1 = All PORTB pull-ups are disabled 0 = PORTB pull-ups are enabled by individual port latch values bit 6 INTEDG0: External Interrupt 0 Edge Select bit 1 = Interrupt on rising edge 0 = Interrupt on falling edge bit 5 INTEDG1: External Interrupt 1 Edge Select bit 1 = Interrupt on rising edge 0 = Interrupt on falling edge bit 4 INTEDG2: External Interrupt 2 Edge Select bit 1 = Interrupt on rising edge 0 = Interrupt on falling edge bit 3 Unimplemented: Read as ‘0’ bit 2 TMR0IP: TMR0 Overflow Interrupt Priority bit 1 = High priority 0 = Low priority bit 1 Unimplemented: Read as ‘0’ bit 0 RBIP: RB Port Change Interrupt Priority bit 1 = High priority 0 = Low priority

Ahmed Hussam32 bit 7 INT2IP: INT2 External Interrupt Priority bit 1 = High priority 0 = Low priority bit 6 INT1IP: INT1 External Interrupt Priority bit 1 = High priority 0 = Low priority bit 5 Unimplemented: Read as ‘0’ bit 4 INT2IE: INT2 External Interrupt Enable bit 1 = Enables the INT2 external interrupt 0 = Disables the INT2 external interrupt bit 3 INT1IE: INT1 External Interrupt Enable bit 1 = Enables the INT1 external interrupt 0 = Disables the INT1 external interrupt bit 2 Unimplemented: Read as ‘0’ bit 1 INT2IF: INT2 External Interrupt Flag bit 1 = The INT2 external interrupt occurred (must be cleared in software) 0 = The INT2 external interrupt did not occur bit 0 INT1IF: INT1 External Interrupt Flag bit 1 = The INT1 external interrupt occurred (must be cleared in software) 0 = The INT1 external interrupt did not occur

Timer 0 with interrupt  Timer 0 interrupts when an over flow happens in tmr0l (when TMR0 is in 8 bits mode)  To use timer 0 there are three SFR are used  1- T0CON  2- TMR0L  3- TMR0H Ahmed Hussam33

Ahmed Hussam 34 bit 7 TMR0ON: Timer0 On/Off Control bit 1 = Enables Timer0 0 = Stops Timer0 bit 6 T08BIT: Timer0 8-bit/16-bit Control bit 1 = Timer0 is configured as an 8-bit timer/counter 0 = Timer0 is configured as a 16-bit timer/counter bit 5 T0CS: Timer0 Clock Source Select bit 1 = Transition on T0CKI pin 0 = Internal instruction cycle clock (CLKO) bit 4 T0SE: Timer0 Source Edge Select bit 1 = Increment on high-to-low transition on T0CKI pin 0 = Increment on low-to-high transition on T0CKI pin bit 3 PSA: Timer0 Prescaler Assignment bit 1 = TImer0 prescaler is NOT assigned. Timer0 clock input bypasses prescaler. 0 = Timer0 prescaler is assigned. Timer0 clock input comes from prescaler output. bit 2-0 T0PS2:T0PS0: Timer0 Prescaler Select bits 111 = 1:256 Prescale value 110 = 1:128 Prescale value 101 = 1:64 Prescale value 100 = 1:32 Prescale value 011 = 1:16 Prescale value 010 = 1:8 Prescale value 001 = 1:4 Prescale value 000 = 1:2 Prescale value

Digital input output example  Make a program that takes a digital signal from a push buttom so that when you push the button a led illuminates ORG 0X  CLRF PORTD,ACCESS  CLRF LATD,ACCESS  MOVLW 0X01  MOVWF TRISD,ACCESS  AGAIN  BTFSS PORTD,0,ACCESS  BRA L1  BSF PORTD,1,ACCESS  BRA L2  L1  BCF PORTD,1,ACCESS  L2  BRA AGAIN Ahmed Hussam 35

Analog read example  Make a program that read analog signal from a potentiometer so that when the volt is greater 2.5 volt make a led illuminates Ahmed Hussam36

 ORG 0X  MOVLW 0X01  MOVWF ADCON0,ACCESS  CLRF ADCON1,ACCESS  MOVLW 0X2A  MOVWF ADCON2,ACCESS  CLRF PORTD,ACCESS  CLRF LATD,ACCESS  CLRF TRISD,ACCESS  AGAIN  BSF ADCON0,1,ACCESS  L1  BTFSC ADCON0,1,ACCESS  BRA L1  MOVLW 0X80  CPFSLT ADRESH,ACCESS  BRA L2  BCF PORTD,0,ACCESS  BRA L3  L2  BSF PORTD,0,ACCESS  L3  BRA AGAIN Ahmed Hussam 37

Pwm example  Make a program that read an analog signal from a potentiometer and take the result as 8 bit from the adc and use it in the pwm module where the frequency of the signal is 1 KHz Ahmed Hussam38

 ORG 0X  MOVLW 0X01  MOVWF ADCON0,ACCESS  CLRF ADCON1,ACCESS  MOVLW 0X2A  MOVWF ADCON2,ACCESS  CLRF PORTC,ACCESS  CLRF LATC,ACCESS  CLRF TRISC,ACCESS  MOVLW 0X0F  MOVWF CCP1CON,ACCESS  MOVLW 0X07  MOVWF T2CON,ACCESS  AGAIN  BSF ADCON0,1,ACCESS  L1  BTFSC ADCON0,1,ACCESS  BRA L1  MOVFF ADRESH,CCPR1L  BRA AGAIN Ahmed Hussam39

Timer 0 with interrupt example  Make a program of led flasher that make the led illuminats for one second then the led is turned of for one second by using timer 0 in 8 bit mode using interrupt Ahmed Hussam40

 X EQU 0X00  ORG 0X00000  GOTO MAIN  ORG 0X0008  INCF X,F,ACCESS  BCF INTCON,2,ACCESS  RETFIE FAST  MAIN  MOVLW 0XA0  ;MOVLW 0X00  MOVWF INTCON,ACCESS  CLRF X,ACCESS  MOVLW 0X47  MOVWF T0CON,ACCESS  CLRF PORTD,ACCESS  CLRF LATD,ACCESS  CLRF TRISD,ACCESS  CLRF TMR0L,ACCESS  CLRF TMR0H,ACCESS  AGAIN  BTG PORTD,0,ACCESS  ;BCF PORTD,1,ACCESS Ahmed Hussam41

 CALL DELAY  ;BSF PORTD,0,ACCESS  ;CALL DELAY  BRA AGAIN   DELAY  BSF T0CON,7,ACCESS  MOVLW 0X3D  L1  CPFSGT X,ACCESS  BRA L1  CLRF X,ACCESS  BCF T0CON,7,ACCESS  CLRF TMR0L,ACCESS  CLRF TMR0H,ACCESS  RETURN Ahmed Hussam42

Configuration bits for pic 18F4620  title "PIC18F4620 counting program"  list P=PIC18F4620 ;p=18fxxx  #include ; This ?header file? contains all  ;******************************************************************************  ;my configrations  __CONFIG _CONFIG1H, _IESO_OFF_1H &_FCMEN_OFF_1H & _OSC_HS_1H ;_OSC_HSPLL_1H  __CONFIG _CONFIG2L, _BOREN_OFF_2L & _PWRT_OFF_2L  __CONFIG _CONFIG2H, _WDT_OFF_2H  __CONFIG _CONFIG3H, _PBADEN_OFF_3H  __CONFIG _CONFIG4L, _LVP_OFF_4L & _STVREN_OFF_4L  __CONFIG _CONFIG5L, _CP0_OFF_5L & _CP1_OFF_5L & _CP2_OFF_5L & _CP3_OFF_5L  __CONFIG _CONFIG5H, _CPB_OFF_5H & _CPD_OFF_5H  __CONFIG _CONFIG6L, _WRT0_OFF_6L & _WRT1_OFF_6L & _WRT2_OFF_6L & _WRT3_OFF_6L  __CONFIG _CONFIG6H, _WRTB_OFF_6H & _WRTC_OFF_6H & _WRTD_OFF_6H  __CONFIG _CONFIG7L, _EBTR0_OFF_7L & _EBTR1_OFF_7L & _EBTR2_OFF_7L & _EBTR3_OFF_7L  __CONFIG _CONFIG7H, _EBTRB_OFF_7H  Ahmed Hussam 43

 ;******************************************************************************  ;X EQU 0X00  ORG 0X00000  GOTO MAIN  ORG 0X0008   RETFIE FAST   MAIN  ;put your code here   END Ahmed Hussam44

Configuration bits for pic 18F452  title "PIC18F452 counting program"  list P=PIC18F452 ;p=18fxxx,f=inhx32  #include ; This ?header file? contains all   ;******************************************************************************  ;Configuration bits  ; The __CONFIG directive defines configuration data within the.ASM file.  ; The labels following the directive are defined in the P18F458.INC file.  ; The PIC18FXX8 Data Sheet explains the functions of the configuration bits.  ; Change the following lines to suit your application.  __CONFIG _CONFIG1H, _OSCS_OFF_1H & _HS_OSC_1H ; _HSPLL_OSC_1H  __CONFIG _CONFIG2L, _BOR_OFF_2L & _PWRT_OFF_2L  __CONFIG _CONFIG2H, _WDT_OFF_2H  __CONFIG _CONFIG4L, _STVR_OFF_4L & _LVP_OFF_4L  __CONFIG _CONFIG5L, _CP0_OFF_5L & _CP1_OFF_5L & _CP2_OFF_5L & _CP3_OFF_5L  __CONFIG _CONFIG5H, _CPB_OFF_5H & _CPD_OFF_5H  __CONFIG _CONFIG6L, _WRT0_OFF_6L & _WRT1_OFF_6L & _WRT2_OFF_6L & _WRT3_OFF_6L  __CONFIG _CONFIG6H, _WRTB_OFF_6H & _WRTC_OFF_6H & _WRTD_OFF_6H  __CONFIG _CONFIG7L, _EBTR0_OFF_7L & _EBTR1_OFF_7L & _EBTR2_OFF_7L & _EBTR3_OFF_7L  __CONFIG _CONFIG7H, _EBTRB_OFF_7H  ;****************************************************************************** Ahmed Hussam 45

 ;Variable definitions  ORG 0X  GOTO MAIN  ORG 0X00008  RETFIE FAST  MAIN  ;put your code here  END Ahmed Hussam46