ĐẠI HỌC QUỐC GIA TP.HỒ CHÍ MINH TRƯỜNG ĐẠI HỌC BÁCH KHOA KHOA ĐIỆN-ĐIỆN TỬ BỘ MÔN KỸ THUẬT ĐIỆN TỬ. Embedded System Design

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ĐẠI HỌC QUỐC GIA TP.HỒ CHÍ MINH TRƯỜNG ĐẠI HỌC BÁCH KHOA KHOA ĐIỆN-ĐIỆN TỬ BỘ MÔN KỸ THUẬT ĐIỆN TỬ Embedded System Design Chapter 7: Peripherals for embedded systems 7.

1 ĐẠI HỌC QUỐC GIA TP.HỒ CHÍ MINH TRƯỜNG ĐẠI HỌC BÁCH KHOA KHOA ĐIỆN-ĐIỆN TỬ BỘ MÔN KỸ THUẬT ĐIỆN TỬ Embedded System Design Chapter 7: Peripherals for embedded systems 7.1 Digital parallel input / output 7.2 LCD interfacing 7.3 Analog input /output 7.4 Serial communication Bộ Môn Kỹ Thuật Điện Tử - ĐHBK Analog Input Allows an external voltage to be converted to digital form, stored and processed This type of input occurs in data loggers, control systems, digital audio and signal processors The PIC microcontrollers is designed specifically for highspeed analog signal processing 2 1

2 Analog input with PIC 16 Series Device Pins Features 16F873A 16F876A 16F874A 16F877A 28 3 parallel ports, 3 counter/timers, 2 capture/compare/pwm, 2 serial, 5 10-bit ADC, 2 comparators 40 5 parallel ports, 3 counter/timers, 2 capture/compare/pwm, 2 serial, 8 10-bit ADC, 2 comparators 3 The PIC16F87XA ADC module Functional blocks for the A/D converter in medium-end PIC microcontrollers. A/D, successive approximation analog-to-digital converter; SHA, sample-and-hold 4 amplifier; AMUX, analog multiplexer. 2

Analog Setup The PIC 16F877 has eight analog inputs: RA0, RA1, RA2, RA3, RA5, RE0, RE1, RE2 being renamed AN0 to AN7.

3 Analog Setup The PIC 16F877 has eight analog inputs: RA0, RA1, RA2, RA3, RA5, RE0, RE1, RE2 being renamed AN0 to AN U1 OSC1/CLKIN RB0/INT OSC2/CLKOUT RB1 MCLR/Vpp/THV RB2 RB3/PGM RA0/AN0 RB4 RA1/AN1 RB5 RA2/AN2/VREF- RB6/PGC RA3/AN3/VREF+ RB7/PGD RA4/T0CKI RA5/AN4/SS RC0/T1OSO/T1CKI RC1/T1OSI/CCP2 RE0/AN5/RD RC2/CCP1 RE1/AN6/WR RC3/SCK/SCL RE2/AN7/CS RC4/SDI/SDA RC5/SDO RC6/TX/CK RC7/RX/DT PIC16F877 RD0/PSP0 RD1/PSP1 RD2/PSP2 RD3/PSP3 RD4/PSP4 RD5/PSP5 RD6/PSP6 RD7/PSP CCS C Analog Input Functions 6 3

4 CCS C Analog Input Functions 7 CCS C Analog Input Functions 8 4

9 Example RV1 1k 13 14 1 2 3 4 5 6 7 8 9 10 U1 OSC1/CLKIN RB0/INT OSC2/CLKOUT RB1 MCLR/Vpp/THV RB2 RB3/PGM RA0/AN0 RB4 RA1/AN1 RB5 RA2/AN2/VREF- RB6/PGC RA3/AN3/VREF+ RB7/PGD RA4/T0CKI RA5/AN4/SS

5 9 Example RV1 1k U1 OSC1/CLKIN RB0/INT OSC2/CLKOUT RB1 MCLR/Vpp/THV RB2 RB3/PGM RA0/AN0 RB4 RA1/AN1 RB5 RA2/AN2/VREF- RB6/PGC RA3/AN3/VREF+ RB7/PGD RA4/T0CKI RA5/AN4/SS RC0/T1OSO/T1CKI RC1/T1OSI/CCP2 RE0/AN5/RD RC2/CCP1 RE1/AN6/WR RC3/SCK/SCL RE2/AN7/CS RC4/SDI/SDA RC5/SDO RC6/TX/CK RC7/RX/DT LCD1 VDD RD0/PSP0 RD1/PSP1 RD2/PSP2 RD3/PSP3 RD4/PSP4 RD5/PSP5 RD6/PSP6 RD7/PSP RXD VSS MILFORD-2X16-BKP PIC16F

6 Example 11 RV5(1) V= Voltage measurement R3 LCD1 VDD RV5 120R R1 680R MILFORD-2X16-BKP RXD VSS 1k RV6 1k RV4 1k RV7 1k RV3 1k RV8 1k RV1 1k D1 RV2 1k R2 4k7 BZX79C2V7 U1(RA3/AN3/VREF+) V= U1 OSC1/CLKIN RB0/INT OSC2/CLKOUT RB1 MCLR/Vpp/THV RB2 RB3/PGM RA0/AN0 RB4 RA1/AN1 RB5 RA2/AN2/VREF- RB6/PGC RA3/AN3/VREF+ RB7/PGD RA4/T0CKI RA5/AN4/SS RC0/T1OSO/T1CKI RC1/T1OSI/CCP2 RE0/AN5/RD RC2/CCP1 RE1/AN6/WR RC3/SCK/SCL RE2/AN7/CS RC4/SDI/SDA RC5/SDO RC6/TX/CK RC7/RX/DT PIC16F877 RD0/PSP0 RD1/PSP1 RD2/PSP2 RD3/PSP3 RD4/PSP4 RD5/PSP5 RD6/PSP6 RD7/PSP

7 Voltage measurement Analog Output Basic digital to analogue converter a) general DAC hardware b) output voltage 14 7

8 DAC 15 Typical application DAC Circuit V o 10V A1 2 A2 A

9 Ex: DAC0808 & Serial DAC 17 Waveform Generator 18 9

10 Waveform Generator Source Code (1/3) 19 Waveform Generator Source Code (2/3) 20 10

11 Waveform Generator Source Code (3/3) 21 Class Assignment Design a system to read temperature data from the sensor LM35, and show the result on LCD LCD1 LM016L VSS VDD VEE RS RW E D0 D1 D2 D3 D4 D5 D6 D

12 Serial communication Serial transmission of binary data consists of sending the bits of a word one by one in a consecutive form and using the same pins. Parallel vs. Serial IO 23 simplex vs half duplex vs full duplex 24 12

13 Serial Communication 1.PIC16 USART Serial Link 2.PIC16 SPI Serial Bus 3.I2C Serial Bus 25 USART The universal synchronous/asynchronous receive transmit (USART) device is typically used in asynchronous mode to implement off board, one to one connections. The term asynchronous means no separate clock signal is needed to time the data reception, so only a data send, data receive, and ground wires are needed. It is quick and simple to implement if a limited data bandwidth is acceptable. USART Operation 26 13

14 RS232 driver MAX232 USART USART RS232 Signal 27 USART with PIC microcontroller The PIC has a dedicated hardware RS232 port, but CCS C allows any pin to be set up as an RS232 port, providing functions to generate the signals in software. (a) Connection between two PICs in asynchronous mode (b) Synchronous mode connection. CK is the clock pin, output in the master device and input in the slave device 28 14

15 CCS RS232 Serial Port Functions 29 RS232 Periperal Simulation 30 15

16 The program 31 Outline 1.PIC16 UART Serial Link 2.PIC16 SPI Serial Bus 3.I2C Serial Bus 32 16

17 SPI Bus The serial peripheral interface (SPI) bus provides high speed synchronous data exchange over relatively short distances (typically within a set of connected boards), using a master/slave system with hardware slave selection One processor must act as a master, generating the clock. Others act as slaves, using the master clock for timing the data send and receive. The slaves can be other microcontrollers or peripherals with an SPI interface. The SPI signals are: Serial Clock (SCK) Serial Data In (SDI) Serial Data Out (SDO) Slave Select (!SS) 33 SPI Bus SPI Connection SPI Signals 34 17

18 SPI Operation To transfer data, the master selects a slave device to talk to, by taking its SS line low. Eight data bits are then clocked in or out of the slave SPI shift register to or from the master. No start and stop bits are necessary, and it is much faster than RS232. The clock signal runs at the same speed as the master instruction clock, that is, 5MHz when the chip is running at the maximum 20MHz (16 series MCUs). 35 SPI Driver Functions 36 18

19 SPI Test System Schematic 37 Master and slaves source code 38 19

20 Outline 1.PIC16 UART Serial Link 2.PIC16 SPI Serial Bus 3.I2C Serial Bus 39 I 2 C Bus The interintegrated circuit (I 2 C) bus is designed for short range communication between chips in the same system using a software addressing system. It requires only two signal wires and operates like a simplified local area network. I2C connection I 2 C signals 40 20

21 I 2 C Bus The I 2 C slave chips are attached to a two wire bus, which is pulled up to logic 1 when idle. Passive slave devices have their register or location addresses determined by a combination of external input address code pins and fixed internal decoding. As for SPI, the clock is derived from the instruction clock, up to 5MHz at the maximum clock rate of 20MHz. 41 I 2 C Bus To send a data byte, the master first sends a control code to set up the transfer, then the 8 bit or 10 bit address code, and finally the data. Each byte has a start and acknowledge bit, and each byte must be acknowledged before the next is sent, to improve reliability. The sequence to read a single byte requires a total of 5 bytes to complete the process, 3 to set the address, and 2 to return the data 42 21

I 2 C Functions 43 I 2 C Test System 13 14 1 2 3 4 5 6 7 8 9 10 OSC1/CLKIN RB0/INT OSC2/CLKOUT RB1 MCLR/Vpp/THV RB2 RB3/PGM RA0/AN0 RB4 RA1/AN1 RB5 RA2/AN2/VREF- RB6/PGC RA3/AN3/VREF+ RB7/PGD

22 I 2 C Functions 43 I 2 C Test System OSC1/CLKIN RB0/INT OSC2/CLKOUT RB1 MCLR/Vpp/THV RB2 RB3/PGM RA0/AN0 RB4 RA1/AN1 RB5 RA2/AN2/VREF- RB6/PGC RA3/AN3/VREF+ RB7/PGD RA4/T0CKI RA5/AN4/SS RC0/T1OSO/T1CKI RC1/T1OSI/CCP2 RE0/AN5/RD RC2/CCP1 RE1/AN6/WR RC3/SCK/SCL RE2/AN7/CS RC4/SDI/SDA RC5/SDO RC6/TX/CK RC7/RX/DT DSW1 ON OFF DIPSWC_8 9 +5V R1 4k7 R2 4k U2 SCK A0 SDA A1 WP A2 24FC RD0/PSP0 RD1/PSP1 RD2/PSP2 RD3/PSP3 RD4/PSP4 RD5/PSP5 RD6/PSP6 RD7/PSP SDA SCL TRIG I2C PIC16F877A U

23 I 2 C Test System 45 23

Embedded System Design

ĐẠI HỌC QUỐC GIA TP.HỒ CHÍ MINH TRƯỜNG ĐẠI HỌC BÁCH KHOA KHOA ĐIỆN-ĐIỆN TỬ BỘ MÔN KỸ THUẬT ĐIỆN TỬ Embedded System Design : Hardware design for an embedded system 2. Design block diagrams 3. Design detail