PIC MicroController Training

Transcription

1 PIC MicroController Training Conduct by : Bill Sim simhkeng@yahoo.com 1

2 Practical Microchip PIC16F877A Development using MikroC ( Software/Hardware) Conduct by : Bill Sim simhkeng@yahoo.com Date : 28 Aug 08 PICDEM 2 Plus Board 2

3 Topics covered PICDEMO2 Development Board Digital I/O Hardware interrupt Timers interrupt Serial port Read/Write Internal EEProm ADC Measurement LCD display Pulse Width Modulation - PWM IIC Support Boot loader download Serial port programmer QL200 PIC Development Board ( China ) External EEProm programming Real Time Clock DAC Measurement 3

4 PICDEMO2 PIC Development Board 9V Power Serial Port LED display RB4-RB1 20MHZ Crystal LCD Display Analog input RA0 Program download port Reset button RA4 Button RB0/Interrupt Button 4

5 PICDEMO2 PIC Development Board Interface wiring position 5

6 General Information 6

7 Why Need Microcontroller Need intelligent in the hardware Simplify hardware circuit by firmware Easy to modify/upgrade for new requirement Use less external components ( e.g. build in Analog-to-Digital converter ) Microcontroller ( Intelligent ) Type of microcontrollers: Sensors (Analog/Digital Input) 7 Output (control) - Microchip PIC series such as PIC84, PIC16F877 - Intel Atmel AT90S Motorola 68HC11 - Others

8 Microcontroller A single-chip( semiconductor) computer Incorporate the supporting chip such memories, input/out, ADC, clock circuit into a single chip For simple application, it can operate by itself with minimum components. Operate on a set of instructions ( program ). It fetches the instructions from it program memory, decode the instruction and then execute the required operation. Traditionally programmed by assembly language, but difficult to learn and maintain. Also assembly language different significantly from controller to controller. High level programming language use are C-language or BASIC Mostly are 8 bits, but 16bit or 32 bit microcontroller also available 8

9 Microcontroller Address decoder Timer CPU I /O Ports Digital / ADC / UART etc ROM RAM Inputs / Outputs circuit microprocessor Address address data Control signal Read/write Memory Memory bank microcontroller A microprocessor system Operate in RISC ( reduced instruction set computer) data is 8 bits, but instruction word in 12, 14 or 16 bits to allow the instructions to fetch and execute in one cycle thus speed up the execution process [ CISC ( Complex Instruction Set Computer) both data and instructions are 8 bits wide. CISC microcontroller usually has more than 200 instruction. Code and data are on the same bus and cannot be fetched simultaneously ] 9

10 Why use PIC? Supported by C language, BASIC Have build in Digital I/O and Analog inputs Digital/Analog pins are configurable Build in flash program memory, EERPOM data memory and data memory Build in oscillator circuit( R/C low speed ) or external oscillator Low power and flexible in supply voltage 1K to 32K bytes of flash EEProm program memory Timers, interrupts 33 input ( Analog/Digital ) or output pin Support USART, SPI and I2C Operating clock from 4MHZ to 40 MHZ Flexible voltage supply from 2V (battery) to 5.5V 10

11 PIC Microcontroller Architecture Power supply range from 2V to 5.5 Volt. Some may have standby feature (in ua current) to allow operate by standby battery. Power Reset/Reset input use to reset or initialize the microcontroller externally. It is connected to an R/C circuit which create a reset pulse at power up. It also include a push button for user to reset the circuit if required. Clock the heart beat of a microcontroller. Can be internal R/C, external R/C, crystal (high speed and accurate ). All instruction set execution speed is a multiple of the clock cycle. For PIC, an instruction cycle takes 4 clock periods. Memory RAM, Flash EEProm ( program and data memory) RAM general purpose memory to store data in a program Flash EEProm( program memory ) use to store user program. Nonvolatile and fast. Can be reprogrammed. Normally range from 1K to 32K or higher depending on the microcontroller. Flash EEprom (data memory ) use to store data that required for next power up operation. Range from 256 to few Kbytes. Can be programmed by application software. 11

12 PIC Microcontroller Architecture Timer/counter ( general purpose ) a counter that is driven from external or internal clock. It can be 8 bit or 16 bit and can be software controlled. The counter initial value can be preloaded. After start counting and reaches overflow, an interrupt will occur or an internal bit will change state to allow user to write application. User will then reprogram the counter, do all the necessary bits reset and start counter/timer again. Watchdog timer use to detect a system problem, such as hang up. Commonly use in real time system where the successful termination of one or more activities must be check regularly. 12

13 PIC Microcontroller Architecture Interrupt an interrupt causes the microcontroller to response to external/internal events immediately when it occurs without the need to check on the events. When interrupt occur, the microcontroller will stop its normal operation, save up all the required information and go to execute an special portion of program called interrupt service routine (ISR). After the execution of the ISR, the microcontroller will resume its normal operation. For bigger system, there is different level of priority for interrupt from different devices which can be programmed. Brown-out Detector reset the microcontroller when the power supply voltage falls below a certain value. This prevents the unpredictable operation at abnormal power supply and also prevent the EEprom from corrupted. Sleep mode consume minimum power ( in ua ), only certain intended monitoring is working to allow the circuit to work with battery. Wake up from sleeping mode when there is a reset or the monitoring device is activate. 13

14 PIC Microcontroller Architecture Input/Outputs (build in) Digital I/Os Analog to Digital converters Serial interfaces : UART, SPI, I2C Pulse Width Modulation output USB interface LCD driver Ethernet interface Motor controller interface 14

15 Feature of PIC16F877 Features Program Memoryn (Flash EEProm) Data Memory EEProm I/O Ports ADC ( 10 bits ) Timers External Interrupt Comparator USART (Serial Port) SPI I2C CCP(PWM) PIC16F877A 8K x 14 bit 368 byte 256 byte x 8bit, 1x16bit 1RB0, 4 in group 2 1 hardware Yes Yes 2 15

16 Pin out of PIC16F877 Flash Programing ADC Hardware Interrupt Crystal PWM RS232 I2C 16

17 Design Consideration Programming Language Programming languages ( in additional to assembly language) there are two languages : C language and Basic Language Recommend to use C- Language for better hardware control. Compiler to use If you choose C-language, you have to use C-compiler mikroelektronika offer a free ( with size limitation ) and easy to use compiler with lot of examples. 17

18 Design Consideration Program Download Programmer to use After compiled the program to the Hex code, you need a programmer to download the Hex code to the microcontroller s code memory (flash). 3 methods : * buy the programmer from the chip suppler * design your own programmer. * boot loader method Buy programmer PICkit2 from Microchip company It come with the hardware and software. There is also another development board for starter using 16F690 that you can use in conjunction with this programmer. the programmer uses USB as interface to the PC. Application program is provided for downloading program from PC to the PIC microcontroller. 18

19 Design Consideration Program Download Design your own programmer ( hardware & software ) Hardware there are many information on internet on how to design the serial programmer for the PIC. A simple one is to use PC s serial port where you suppose to get 12V from the serial port pin to program the PIC. A slightly complicated one is to use external power adapter to provide the 12V but still use serial port for this purpose. This is useful if some PC does not give you stable 12V Software After you have the hardware made, you need to have the programmer s software. A free software called WinPic is the best programmer software found so far. You can download from the following site : 19

20 Design Consideration Program Download Boot loader method boot loader is a small piece of firmware that reside inside a microcontroller s code memory and is responsible for downloading future application firmware developed to the microcontroller PIC product to use is 16F877A and above the boot loader and its application program used is FREEware boot loader firmware have to be pre-programmed only once using standard programmer use serial port to download the application firmware developed crystal use is 20MHZ, baud rate of the serial port is 38400bps Boot loader s application program, called PICdownloader, is installed on a PC for downloading purpose Select the Hex file to be download, com port and the baud rate and click the write button. Power OFF/ON the board and the firmware will be downloaded into the controller 20

21 Design Consideration Program Download Boot loader method Reset the target board 21

22 Digital I/O Port A/B/C/D/E PIC 16F877A Digital IO A B C D E 22

23 Digital I/O Your will learn : Hardware How to program digital I/O ports and application How to use push button Switch and eliminate debounce How to flash LEDs Software How to output byte data to hardware port How to handle bit wise ( Input/Output ) for a hardware port How to use delay_ms subroutine How to make human readable flashing 23

24 PortA/E Configuration PortA and PortE can be configured as Digital IO or Analog input (ANx) Two registers need to be configured : ADCON1(A/D control register) and TRISA(data direction register) Analog pins need to define as input pins Bits configuration For RA0 to RA3, RA5, RE0 to RE2 ADCON1 Register TRISA/E Register PortA/E pins Digital input or Digital output or Analog pin Define Digital or analog pin Define input or output pin Note : RA4 is open collector pin To define porta as all digital IO, ADCON1 = 0x06; To define porta as all output pins TRISA = 0x00; To define porta as all input pins TRISA = 0xff; 24

25 ANCON1 Configuration The configuration table for ANCON1 is shown below : only the first 4 bits is used 25

26 PortA/B/C/D/E Configuration PortA/B/C/D/E can be configured as Digital IO via data direction registers TRISA, TRISB,TRISC, TRISD & TRISE Bits configuration TRISX Register Digital input or Digital output Define Digital or analog pin for PORTA/B/C/D/E where X = A or B or C or D For example,to define Port D, bit 0 to 3 as digital input and bit 4 to 7 as digital output, TRISD = 0x0f; 26

27 MikroC Statements Some C Programming statements Write to a port or register byte wise TRISB = 0xff; PORTB = 0x0a; Read from a port or register byte wise If ( PORTB = = 0x38 ) { } Write to port or register bit wise PORTB.F1 = 1; // bit 1 of PORTB Read from a port or register bit wise If ( PORTB.F0 = = 0 ) { } If ( ( PORTB & 0x01) == 0x00 ) { } Complement a port PORTB = ~PORTB ; // 1 become 0, 0 become 1 27

28 MikroC Statements Some C Programming statements Delay time in milliseconds delay_ms (int number); e.g. delay_ms(500); Delay time in microseconds delay_us(int number); e.g. delay_us(200); Variable delay time in milliseconds int mydelay; mydelay = 300; Vdelay_ms( mydelay); 28

29 Interrupts Hardware Interrupt Timer0 Interrupt Multiple Interrupt 29

30 Hardware Interrupt Your will learn : Hardware What is hardware interrupt How use hardware interrupt in 16F877A Parameters that need to consider for interrupt Software How to write interrupt service routine How to program INTCON & OPTION_REG registers Timer 0 interrupt How to handle multiple interrupt 30

31 Interrupt Interrupt is used to reduce the workload of the CPU. A special job will only be done when the interrupt occurs. This special job is placed as part of the software program called interrupt service routine (ISR). CPU will perform its normal operation till an interrupt occur. When it happens, the CPU will stop its normal operation, save up all the registers and then execute the interrupt service routine till its completion. It will then back to its normal operation. When enter into ISR, it is a good practice to disable the interrupt. This is to prevent response to another interrupt when the previous ISR has not completed yet. Before exit the ISR, the interrupt need to be enabled and ready for another hardware interrupt. For 16F877A, there are 3 user defined interrupts ( in additional to 16F877 s standard peripheral interrupts). They are : hardware interrupt ( RB0/INT), Timer0 interrupt and RB4-RB7 group interrupt Other interrupt provided for the feature of 16F877 is called peripheral interrupt and is important for assembly language or C library programmer 31

32 Interrupt Flow Chart Start ISR ucontroller performing normal operation Y Interrupt Occurs? N Disable interrupt/ Save all current jobs Perform special Jobs (interrupt Service routine ) Interrupt Completed? Y Enable interrupt Resume current jobs N 32

33 Hardware Interrupt registers that involved in the interrupt operation, INTCON (0x0b) register and OPTION_REG (0x81) INTCON bit 3, known as RBIE, if set to 1, will inform PIC that RB4 to RB7 will be used as interrupt input group. They can not be select individually. When interrupt occurs, the interrupt flag, bit 1 of INTCON register is set. When this occur, the PIC microcontroller will not respond to any further interrupt. Enable occur INTCON (0x0b) GIE PEIE T0IE INTE RBIE T0IF INTF RBIF Bit 7 Default : x Bit 0 GIE - Global Interrupt Enable bit INTE RB0/INT External interrupt enable bit 33

34 Hardware Interrupt INTCON Register (0x0b) Global Interrupt Enable bit Enable Occur flag Bit 7 GIE PEIE T0IE INTE RBIE T0IF INTF RBIF Bit 0 For peripheral interrupt RB7 RB4 (all) as interrupt For timer-0 (TMR0) - interrupt For External interrupt RB0/INT Default : x 34

35 Hardware Interrupt INTCON Register (0x0b) The Peripheral interrupt enable bit ( PEIE ) have to work with another two sets of interrupt enable registers and flag for a specific features provided by PIC 16F877. they are : PIE1/ PIR1 for Parallel Slave Port Read/Write Interrupt (PSPIE) A/D Converter Interrupt (ADIE) USART Receive Interrupt ( RCIE) USART Transmit Interrupt (TXIE) Synchronous Serial Port Interrupt (SSPIE) CCP1 interrupt (CCP1IE) TMR2 to PR2 Match Interrupt (TMR2IE) TMR1 Overflow Interrupt (TMR1IE) 35

36 Hardware Interrupt INTCON Register (0x0b) PIE2/ PIR2 for Comparator Interrupt (CMIE) EEPROM Write Operation Interrupt (EEIE) Bus Collision Interrupt (BCLIE) CCP2 Interrupt (CCP2IE) The C language function library provided by vendor will take care of all these standard feature interrupt. We will focus on non-peripheral related interrupts. 36

37 Option register,option_reg, bit 6, INTEDG ( Interrupt Edge), when set, will cause the PIC to be interrupt on rising edge. When clear, the PIC will be interrupted on falling edge. The default interrupt setting is on rising edge. OPTION_REG (0x81) Hardware Interrupt RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 Bit 7 Default : Bit 0 INTEDG = 1 INTEDG = 0 INTEDG Interrupt Trigger Edge RB0/INT INTEDG = 1 INTEDG = 0 When PB4 to PB7 are used as interrupt, you cannot select individual pins on PORTB to serve as an interrupt input. It may be not so practical to use them as interrupt as you can not make use of these pin as I/O. 37

38 Option register,option_reg, bit 7, RBPU, when clear (=0), will turn on PORTB s internal pull-up (weak) as a high. The respective internal pull-up of the PORTB s pin will automatically turn-off when the PORTB pin is assign as output. OPTION_REG (0x81) Hardware Interrupt RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 Bit 7 5V Default : Bit 0 RB0 16f877 /RBPU = 0 Depending on circuit designed 38

39 Hardware Interrupt OPTION_REG Register (0x81) OPTION_REG register contains various control bits to configure the TMR0 prescaler / WDT postscaler, external interrupt(rb0/int), TMR0 and weak pull up on PORTB TMR0 Clock source TMR0 Source edge type Prescaler Bit 7 RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 Bit 0 PORTB pull-up Prescaler rate select RB0/INT interrupt edge type Prescaler assign to WDT or Timer0 Default :

40 OPTION_REG Register (0x81) Hardware Interrupt OPTION_REG (0x81) RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 Bit 7 Default : INTEDG Interrupt Trigger Edge Bit 0 INTEDG = 1 INTEDG = 0 40

41 Hardware Interrupt Some MikroC Programming statements Hardware Interrupt INTCON.F7=1; //enable global interrupt INTCON.F6=1; // enable all peripheral interrupt INTCON.F4=1; //set PB0 as the external interrupt OPTION_REG.F6=0; //interrupt at negative edge OPTION_REG.F7=0; //turnon RB0's internal pullup (weak) void interrupt() // funciton name of interrupt service routine { INTCON.F4=0; //disable RB0/INT ISR jobs INTCON.F1=0; //MUST HAVE -- clear interrupt flag INTCON.F4=1; //enable global interrupt } 41

42 Timer Interrupt 42

43 Timer Interrupt Timer0, TMR0, is a 8 bit binary up counter Count driven by external or internal clock source. TMR0 register stores the counter value which can be reset or preloaded with value Count increase with each input pulse until TMR0 overflow (from 0xFF to 0x00) Overflow triggered timer0 interrupt. The interrupt service routine will then be executed. 43

44 Timer Interrupt TMR0 register and prescaler relationship d Load TMR0=0 Prescale After 255 Pulse by timer0 d Interrupt Set RB1=~RB1 Load TMR0=0 For a 20MHZ crystal, d= ((# of tick) * 4 * Prescaler * 1000 )/(clock frequency) Case 1 : Prescaler = 1 d = 255 * 4 * 1 * 1000 / = 51 us Case 2 : Prescaler = 1:2 d = 255 * 4 * 2 * 1000 / = 102 us Case 3 : Prescaler = 1 d = 255 * 4 * 256 * 1000 / = 13.6ms Case 4 : Prescaler = 1 d = 95 * 4 * 256 * 1000 / = 4.86 ms 44

45 Multiple Interrupts 45

46 Multiple Interrupt When there is multiple interrupt requirement, the interrupt service function must check for what interrupt has happen and then execute the respective interrupt handler. E.g. RB0/INT or TMR0 handler The INTCON_REG provide the flag of the interrupt. INTCON_REG Bit 7 GIE PEIE T0IE INTE RBIE T0IF INTF RBIF Bit 0 46

47 Some MikroC Programming statements Timer Interrupt OPTION_REG = 0x18; // Prescale to WDT i.e TMR0 no prescale Multiple Interrupt void interrupt() { void rb0_interrupt(void) { jobs here } void tmr0_interrupt(void) { jobs here } Multiple Interrupt INTCON.F7 = 0; // disable further interrupt if ((INTCON & 0x02)==0x02){rb0_interrupt(); } // check for hardware interrupt if ((INTCON & 0x04)==0x04){tmr0_interrupt();} //check for timer0 interrupt INTCON=0xf0; //enable global and the required interrupt } 47

48 USART (Serial / RS232) Communication 48

49 USART/Com port/ Serial Port USART stands for Universal Synchronous Asynchronous Receiver Transmitter RS232, Serial Port, COM Port means the same thing Most of the desktop PC & engineering instrumentation still support serial port Its family standard RS422 can connect many devices together using 3 wires For PIC 16F877, USART is access through RC7 for Receive and RC6 for Transmit at TTL level ( hardware USART ) A RS232 line driver need to interface with RC7/RC6 to deliver the RS232 standard (i.e. high voltage level for long distance driving ) via a Max232 chip. Refer to any standard RS232 article for more detail description 49

50 Hardware USART RC6/RC7 provide signal at TTL level. MAX232 converts TTL high level to -13V and TTL low level to +13V which is good for data transmission on long wire. When No transmission, the signal is high, start bit is low, Stop bit is high 16F877A circuit RC6 RC7 MAX232 (1/2) RS232 v Start bit (0) Stop bit (1) D0 D1 D7 t 50

51 MikroC Statements MikroC support both software USART and hardware USART Software USART commands soft_uart_init ( port-number, rx-pin, tx-pin, baud rate, mode) mode = 0 : data not inverted e.g Soft_Uart_Init( PORTB, 0,1, 9600,0); PB0 rx, PB1-tx Soft_Uart_Read(&Rx_Error) e.g do { mychar = Soft_Uart_Init(&Rx_Error); } while (Rx_Error); error is normally 1 and become 0 when a byte is read from the port Soft_Uart_Write( character ); e.g. Soft_Uart_Write( A ); 51

52 MikroC Statements Hardware USART Commands Hardware USART can support higher baud rate Parameters need to setup for communication only baud rate is needed Baud rate : or others supported baud rate Rest of parameters are set, by the MikroC as follows : number of data bit : 8 bits number of stop bit : 1 Parity bit : N ( no parity ) e.g. USART_init(38400); 4 C-statements involve in serial communication Char USART_Write(char data) - 1 byte Char USART_Read(Void) Void USART_init( const long baudrate) Char USART_data_ready(void) 52

53 Read/Write Internal Data EEProm 53

54 Read/Write to Internal Data EEProm 16F877 has 256 byte of data memory and 8K of program memory that allow data and program remain in the device when power of switch off. The 6 SFR ( Special Function Register) use to support these functions are : EECON1, EECON2( Not a physical register ), EEDATH: EEDATA ( Holds 14 bits of data for Read/Write ) and EEADRH:EEADR ( holds the 13 bit address of the program memory location being access ). 54

55 Read/Write to Internal Data EEProm 55

56 MikroC Statements In MikroC, to write and read to internal EEProm, use the following statements : Unsigned short eeprom_read(unsigned short address); e.g. char read_data; read_data = eeprom_read(0x30); void eeprom_write(unsigned integer address, unsigned short data); e.g. eeprom_write(0x30, 0x11); 56

57 LCD Display 57

58 LCD Display The interface to LCD display is done through a set of data bit and control bits For the demo circuit, it uses 4 bits, RD7-RD3, for data instead of full 8 bits For MikroC, there is a predefine hardware interface as specified in the programming manual page 241, all LCD pins must connected to a single port. If you are using different hardware connection, normally the case, you can use the programming generator ( or you can write your own code ) provided by MikroC to generate the functions required to program the LCD based on your hardware connection (e.g. see below) ( called LCD4 Optimum Module by Warren Schroeder April 25, 2007 ) RD7-RD3 PIC 16F877A RA1 - RS RA2 - R/W RA3 - E LCD 58

59 LCD Display MiKroC s LCD Library s hardware requirement RB2-RB5 PIC 16F877A RB0 - RS LCD All pins must within a Port. Otherwise cannot use the library RB1 - E Lcd_Config (port-name, RS-pin, EN-pin, R/W-pin, D7-pin, D6-pin, D5-pin, D4-pin) R/W-pin is not use, should connect to ground (always write) e.g. Lcd_Config ( &PORTB, 0,1,2,3,4,5) Lcd_Init(Port-name ); Lcd_Init(&PORTB); Lcd_Out(row, column,text); Lcd_Out(1,2, MyTest ); Lcd_Out_Cp(text); Lcd_Out( Hello); output text from the Current Position Lcd_Chr ( row, column, character); Lcd_Chr(1,2, M ); Lcd_Chr_Cp(character); Lcd_Chr_Cp( M ); 59

60 LCD Display Program Generator Use when the LCD interface pins involve more than one PORT Select PIC type Define RS pin connection Define E pin connection Define Data pins ( 4 pins) connection In the software, set always write mode ( PORTA.F2 = 0 for /W ) For PICDEM2 60

61 LCD Application Constant Lcd_Cmd(command constant); Command constant LCD_CLEAR LCD_RETURN_HOME LCD_FIRST_ROW LCD_SECOND_ROW LCD_THIRD_ROW LCD_FORTH_ROW LCD_BLINK-CURSOR-ON LCD_TURN_ON LCD_TURN_OFF LCD_MOVE_CURSOR_LEFT LCD_MOVE_CURSOR_RIGHT LCD_SHIFT_LEFT LCD_SHIFT_RIGHT 61

62 Analog Measurement (Analog-to-Digital Converter) 62

63 Purpose of ADC To measure an analog voltage (e.g. sensor) input and convert to digital for the micro-controller to interpret and make decision Sensor/transducer produced very small analog voltage. In some cases it could be uv ( micro-volt ) and it needs an analog amplifier to amplify the signal to a measurable analog voltage. In order for a computer/microprocessor/micro-controller to interpret the analog signal, the analog signal need to convert to digital, for at least 8 bits or more. ( 10 bits for PIC16F877 ) If the analog signal is small, you have to use lower Vref in PIC16F877 ADC measurement in order to get more accurate digital measurement Sensor A ADC 63

64 ADC Block Diagram CS2-CS0 AN7 AN6 AN5 AN4 AN3 AN2 AN1 AN0 VDD Verf+ ADC Converter Reference Voltage PCFG<3:0> 10 bits Verf- VSS 64

65 ADC setup 3 Registers involve in the ADC Operation : TRISA, ADCON1 and ADCON0 Vref can be VDD or other value VDD V = (bits value) *(Vref / 1024) Vref 2 AN0 10 bits ADC converter 16F877 3 AN1 VSS VDD When measure small voltage, it is more accurate to supply own Vref Due to VDD may vary, it is more accurate to use a Vref instead of using VDD as Vref VSS Symbol Hardware port AN7 RE2 AN6 AN5 AN4 AN3 AN2 AN1 AN0 RE1 RE0 RA5 RA3 RA2 RA1 RA0 65

66 What need to be set for measurement? How many analog ports to use and Vref to use : PCFG3-PCFG0 ANCON1 Set the respective hardware ports to be input for ADC operation TRISA and/or TRISE Define measurement data to be read is Right justify or Left justify ADFM bit in ANCON1 Select AD conversion clock : ADCS2 in ANCON1 and ADCS1 & ADCS0 in ANCON0( A/D control register 0) For each channel to be measured, select the channel number and set ADC to be ON : CHS2-CHS0 bits and ADON bit in ANCON0 For each channel selected, set the GO//Done bit in ANCON0 to 1 and start ADC measurement. When ADC measurement completed, the GO//Done bit will be set to 0. 10us Conversion time should be sufficient ( refer to data sheet for detail calculation) in 66

67 Analog to Digital conversion setup When use AN0 & AN1 as input, from the configuration table, select PCFG3 to PCFG0 to be 0100 TRISA = 0x0b; PortA0, PortA1 & PortA3 are inputs, PortA2, PortA4 PortA7 are outputs ADCON1 AN0,AN1,AN3 analog, AN2, AN4 AN7 all digital VREF+ = VDD, VREF = Vss ( internal ) ADFM ADCS2 - - PCFG3 PCFG2 PCFG1 PCFG0 ADCS1 GO/ ADCS0 CHS2 CHS1 CHS0 - ADON ADCON0 /Done 1 Enable A/D measurement Select AD conversion clock 110 = FOSC/64 for 20MHZ crystal OK Select channel 0 = 1 Start A/D conversion =0 A/D conversion completed Right justify ADRESH,ADRESL = xx,xxxxxxxx 67

68 ANCON1 Configuration The configuration table for ANCON1 is shown below : only the first 4 bits is used 68

69 ANCON1 Configuration When ports are selected for analog input, the conversion clock rate ( use in conjunction with ADCON0 ) and the ADC read result format are set according to the following format : 69

70 ADCON0 Configuration ADCON1 ADCON0 70

71 Important ADC Program ADC Measurement Steps /* Read AN1 port, use FOSC/64 */ ADCON0= 0x89; // importnant : switch port first, don't measure delay_ms(100); // important : for it to stabilize ADCON0 = 0x8d; // AN1 read delay_ms(100); while( ADCON0 & 0x04){} // check conversion completed? datal= ADRESL; // read result datah=adresh; write_adc_result(datah,datal); // output result to display 71

72 Pulse Width Modulation 72

73 PWM stands for Pulse Width Modulation PWM is basically sending a pulse with various duty cycle so the receiver device, which is a PWM operated, can perform a specific function. Example : Servo motor, beeper, flash light etc w Pulse Width Modulation T Duty cycle = W / T * 100% When the pulse width is longer, the flashing LED will be brighter or the beeper will have different sound frequency. For PWM servo motor, the motor will turn in different direction. PWM pulse can be generated by pulse a output pin the Hi & Lo with time delay to generate the pulse or can be done by a specific PWM output pins For 16F877, it has two pins RC1 ( CCP2 ) and RC2 (CCP1) that response to generate the PWM pulses 73

74 Pulse Width Modulation In MiKroC the statements use to generate the PWM are follows : void PWM_Init(long freq); - initialize PWM frequency void PWM_Change_Duty( char duty_ratio ); - set duty cycle where duty_ratio ranges from 0 to 255 duty cycle = ( % * 255 ) / % duty cycle, duty_ratio = % duty cycle, duty_ratio = 255 void PWM_Start (void) ; - start PWM void PWM_Stop (void); - stop PWM For 16F877 chip, there is two PWMs, you can use PWM1 and PWM2 syntax to generate two different PWM pulse 74

75 Pulse Width Modulation In MiKroC the statements example RC1 ( CCP2- PWM2 ) RC2 ( CCP1- PWM1 ) PWM1_Init(5000); PWM2_Init(5000); PWM1_Change_Duty(127); // 50% duty cycle PWM2_change_Duty(20); // 7.84% duty cycle PWM1_start(); PWM2_start(); // determine PWM to start while( PORTA.F4 == 0){} // when button release, stop PWM1_stop(); PWM2_stop(); 75

76 PWM for Servo Motor Control For motor control, pulses with various duty cycle are used for DC Motor speed control and servo motor position control For servo motor position control, different pulse width will cause the motor to rotate at different angle. The general guide line for servo motor rotation are as follows : 1 ms 1.5 ms center 2.0 ms right Left 18 ms 18 ms 18 ms 76

77 IIC Serial Communication 77

78 IIC Serial Communication System level serial data communication method Need two signal lines : data (SDA) and clock (SCL) Allow a master device control up to 1023 other devices Signal lines have 5V pull up Each data bit is accompany by a clock pulse Clock speed is programmed by preload the baud rate generator up to 1MHZ 5V 4.7K 4.7K Master Slave Slave start acknowledgement SDA SCL SDA SCL 78

79 IIC Serial Communication Interface to a 256K EEProm 5V 16F877A circuit RC4 RC3 4.7K SDA SCL K 5V 8 SDA SCL A0 A1 A2 24LC K IIC Serial EEProm 4 79

80 IIC Serial Communication In MiKroC the statements use in IIC communication are follows : void I2C_Init(long clock); char I2C_Start(void); void I2C_repeated_Start(void); char I2C_Is_Idle(void); char I2C_Rd(char ack); ack=0 means no acknowledge char I2C_Wr(char data); void I2C_Stop(void); 80

81 IIC Serial Communication Write Byte I2C_Start(); I2C_Wr(0xA0); //control byte for write I2C_Wr(addrhighbyte); //address to write - high byte I2C_Wr(addrlowbyte); //address to write - low byte I2C_Wr(data); //data I2C_Stop(); 81

82 IIC Serial Communication Random read address I2C_Start(); I2C_Wr(0xA0); //control byte for write I2C_Wr(addrhighbyte); //address to read high - byte I2C_Wr(addrlowbyte); //address to read low - byte I2C_Repeated_Start(); I2C_Wr(0xA1); //control byte for read data = I2C_Rd(0u); I2C_Stop(); 82

83 Read/Write External EEprom 93LC46 using I/O Ports QL200 PIC Development Board ( China ) 83

84 External EEprom using I/O Functional block diagram Parameters: data bits 1 stop bit N parity 16F877A circuit RC2 RC3 RC5 RC4 CS CLK DI DO Memory locations to write/read are : 0x01, 0x02,0x3f,0x18,0x2a VCC NC NC VSS 93LC46 84

85 External EEprom using I/O 93LC46 is a 1024-bit non-volatile, serial EEProm. 6 bit of address and 16 bit of data > total = 64 x 16 = 1024 bit 4 signal pins : CS chip select, SK clock pin, DI data in, DO-data out. Provide write enable or disable function to protect the data All functions such as read, write, write enable etc required a predefine function header before the address and/or data see datasheet for detail Write data to a address provide 6 bits of address follow by 16 bits of data to the DI pin Read data at address provide 6 bit of address and read data from the DO pin 4 important functions : Write enable, write disable, read and write 85

86 Write enable External EEprom using I/O Pin Layout Write disable 86

87 External EEprom using I/O Write data operation must have 87

88 External EEprom using I/O Read data operation 88

89 External EEprom using I/O Program Methodolgy DI1, DI0 input data bit high, low CS1, CS0 chip select bit high, low Clk - generate 1 clock pulse void DI1(void) { PORTC.F5=1; delay_us(200); } void DI0(void) { PORTC.F5=0; delay_us(200); } void clk (void) { PORTC.F3 = 0; delay_us(100); PORTC.F3 = 1; delay_us(200); PORTC.F3 = 0; delay_us(100); } void CS1(void) { PORTC.F2=1; delay_us(200); } void CS0(void) { PORTC.F2=0; delay_us(200); } 89

90 Real Time Clock QL200 PIC Development Board ( China ) 90

91 Real Time Clock (RTC) Your will learn : Hardware Function of Real Time Clock Software How to program the Real Time Clock : Write Date and Time Read Date and Time Protect / Un-Protect RTC for writing 91

92 Real Time Clock Project Program the date and time with the following information : Date : 23 /07/08 Time : 14:50:00 Read back the Date and time every seconds and display on LCD and on serial port Functional block diagram Parameters: 16F877A circuit RB0 RB4 RB5 CLK I/O RST data bits 1 stop bit N parity Date:23/07/08 Time:14:59:20 RTC DS1302 LCD Display 92

93 Real Time Clock (RTC) RTC counts Hour:Minute:Second and Day/Month/Year with other features such as 12/24 hour, AM/PM option RTC used here is DS1302, 8 pins IC(3 signal wires), 2V to 5.5V operation RTC chip need to work with an crystal oscillator circuit (32.768kHz) RTC also provide serial interface for data I/O ( read/write ) and clock Two power supplies input for RTC, One for battery and one for normal DC power Date and Time is set through the programming to a set of predefine memory location with the desire Date and Time value in human understandable value. These value are written directly to the memory location in HEX format without conversion to hex value. e.g. 14 hr, 20 min, 59 sec write as 0x14, 0x20 and 0x59 93

94 Real Time Clock (RTC) Memory locations for writing and reading of Date and Time Max = 5,need 3 bit Max = 9, need 4 bit Location for read Location for write 94

95 Digital to Analog Converter TLC5615C QL200 PIC Development Board ( China ) 95

96 Digital to Analog Converter TLC5615C 10 bit CMOS voltage output DAC 3 wire interface High impedance reference input 8 pin package 96

97 Digital to Analog Converter To program the TLC5615C, need to send 16 bits of serial data into the shift register of TLC5615C Only 10 bits are for voltage programming : Vout = 2 * (V ) * refin V 10 bits 1024 VH High byte H1 H0 VL Low byte L7 L6 L5 L4 L3 L2 L1 L0 Vout If Vrefin = 2.0v, VH = 0x02 VL= 0xab; Vout = 2 * (2) * V ( ) 1024 = 4 * (683/1024) = 2.67 v 97

98 Digital to Analog Converter The bit pattern send to the TLC5615C serially are : 0,0,L0,L1,L2,L3,L4,L5,L6,L7,H0,H1,D,D,D,D where D dummy bit, 0 - zero Every data bit will send to the TLC5615C when the clock is at high transition. /CS must be low before the first clock take place and must be high after the last 16 th bit is clocked. 98

99 Digital to Analog Converter 99

100 Digital to Analog Converter Project Functional block diagram REF In = VDD RC2 - CS RC3 - SCLK RC5 - DIN TLC 5615 D/A VOUT PIC 16F877A RB0 Lowest 8 DAC bit to PORTB display RB7 RA0 To advance the DAC output to different value 100

101 Digital to Analog Converter Programming sequence are : /CS = 0 send in 4 clock pulse ( Din don t care dummy ) Reverse the bit sequence for High byte and low byte for each of the 10 bit ( high or low ), send in the clock to clock in the bit send in two clock with DIN= 0 /CS = 1 101

102 Some Useful Functions 102

103 Useful functions function Lo (number) Hi (number) Higher (number) Highest (number) Description Return ( bit 7-0 ) of a number Return ( bit 15-8 ) of a number Return ( bit )of a number Return (bit ) of a number Delay_us (number) Delay_ms (number) Vdelay_ms ( variable) Software delay in microseconds Software delay in milliseconds Software delay using program variable EEProm_Write (address, data) EEProm_read (address) Write the eeprom address with the data Read the eeprom address 103

104 Useful functions function Isalnum Isalpha Isntrl Isdigit Islower Isprint Isupper Toupper Tolower Description Return a 1 if is alphanumeric ( a-z. A-Z, 0-9) Return a 1 if it is a-z, A-Z Return a 1 if is control character ( decimal 0-31 and 127) Return a 1 if is 0-9 Return a 1 if is lowercase Return a 1 if is is printable ( decimal ) Return a 1 if is is uppercase Convert a character to uppercase Concert a character to lowercase 104

105 Useful functions function Abs Atof Atoi Atol Max Min Rand Srand Xtoi Description Return the absolute value Convert ASCII character to floating point number Convert ASCII character to integer Convert ASCII to long integer Return the greater of two integers Return the lesser of two integers Return a random number between 0 and srand() must be called first Generate a seed for function rand to call Convert input string consisting of hex digits into integer 105

106 Useful functions function Strcat, strncat Strchar, strpbrk Strcmp, strncmp Strcpy, strncpy Strlen Description Append two strings Locate the first occurrence of a character in a string Compare two strings Copy one string into another one Return the length of a string 106

107 Useful functions function ByteToStr shorttostr WordToStr IntToStr LongToStr FloatToStr Bcd2Dec Dec2Bcd Description Convert a byte into string Convert a short into string Convert an unsigned word into string Convert an integer into string Convert a long into string Convert a float into string Convert a BCD number into decimal Convert a decimal number into BCD 107

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