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    SERIAL COMMUNICATION WITH AT89C2051 Search Results

    SERIAL COMMUNICATION WITH AT89C2051 Result Highlights (5)

    Part ECAD Model Manufacturer Description Download Buy
    LBAA0QB1SJ-295 Murata Manufacturing Co Ltd SX1262 MODULE WITH OPEN MCU Visit Murata Manufacturing Co Ltd
    GRJ43DR7LV224KW01K Murata Manufacturing Co Ltd Chip Multilayer Ceramic Capacitors with Soft Termination for General Purpose Visit Murata Manufacturing Co Ltd
    GRJ55DR7LV474KW01L Murata Manufacturing Co Ltd Chip Multilayer Ceramic Capacitors with Soft Termination for General Purpose Visit Murata Manufacturing Co Ltd
    GRJ55DR7LV334KW01K Murata Manufacturing Co Ltd Chip Multilayer Ceramic Capacitors with Soft Termination for General Purpose Visit Murata Manufacturing Co Ltd
    GRJ43QR7LV154KW01L Murata Manufacturing Co Ltd Chip Multilayer Ceramic Capacitors with Soft Termination for General Purpose Visit Murata Manufacturing Co Ltd

    SERIAL COMMUNICATION WITH AT89C2051 Datasheets Context Search

    Catalog Datasheet Type Document Tags PDF

    AT24C04 with AT89C2051

    Abstract: interfacing 24c04 with 8051 with lcd 74C922 IC 74c922 lcd interface with at89c2051 AT89C2051 microcontroller 20 pin ic i2c interfacing with 8051 Interfacing RTC using I2C protocol INTERFACING MEMORY WITH 8051 THROUGH I2C PROTOCOL 24C04 code example assembly
    Text: Two-Wire Peripheral Expansion for the AT89C2051 Microcontroller The attribute shared by most embedded controllers is their ability to interact with the outside world. While this fact is generally accepted, the form this I/O takes includes everything from parallel and bitaddressable digital I/O, analog I/O, as


    Original     		AT89C2051 AT24C04 with AT89C2051 interfacing 24c04 with 8051 with lcd 74C922 IC 74c922 lcd interface with at89c2051 AT89C2051 microcontroller 20 pin ic i2c interfacing with 8051 Interfacing RTC using I2C protocol INTERFACING MEMORY WITH 8051 THROUGH I2C PROTOCOL 24C04 code example assembly PDF

    8051 interfacing with adc pcf8591

    Abstract: keypad 4x4 c code for 8051 IC 74c922 keypad 4x4 matrix c code for 8051 74C922 74C922 PCF8574 at24C04 code example assembly interfacing 24c04 with 8051 with lcd datasheet keypad 4x4 74c922 lcd interface with at89c2051
    Text: Two-Wire Peripheral Expansion for the AT89C2051 Microcontroller The attribute shared by most embedded controllers is their ability to interact with the outside world. While this fact is generally accepted, the form this I/O takes includes everything from parallel and bitaddressable digital I/O, analog I/O, as


    Original     		AT89C2051 8051 interfacing with adc pcf8591 keypad 4x4 c code for 8051 IC 74c922 keypad 4x4 matrix c code for 8051 74C922 74C922 PCF8574 at24C04 code example assembly interfacing 24c04 with 8051 with lcd datasheet keypad 4x4 74c922 lcd interface with at89c2051 PDF

    S4051

    Abstract: AT89S051 serial communication with AT89c2051 AT89c2051 Application Note AT89c2051 Analog AT89C2051 microcontroller interrupt AT89C2051 microcontroller interrupt timer code AT89C2051 microcontroller AT89S2051 AT89C2051 internal memory map
    Text: Migrating from AT89C2051/C4051 to AT89S2051/S4051 Flash Microcontrollers New Features • 8-bit Pulse-width Modulation • Enhanced UART Serial Port with Framing Error Detection and Automatic • • • • • • • • • Address Recognition On-chip Analog Comparator with Selectable Interrupt


    Original     		AT89C2051/C4051 AT89S2051/S4051 AT89S2051/S4051. S4051 AT89S051 serial communication with AT89c2051 AT89c2051 Application Note AT89c2051 Analog AT89C2051 microcontroller interrupt AT89C2051 microcontroller interrupt timer code AT89C2051 microcontroller AT89S2051 AT89C2051 internal memory map PDF

    Hitachi 2 x 16 character display with backlight

    Abstract: ASC11 44780 lcd lcd connector lcd 44780 4 DIGIT LCD DISPLAY 40 PIN with MAX controller hitachi 44780 AT89C2051 HD44780 P301
    Text: Issued July 1998 10784 LCD Message Controller Instruction Leaflet RS stock no. 294-8847 LCD character module controller specification The liquid crystal display module controller is designed around a high performance AT89C2051 8bit microcomputer. The controller can drive all the LCD character modules in the RS range and any


    Original     		AT89C2051 HD44780 Hitachi 2 x 16 character display with backlight ASC11 44780 lcd lcd connector lcd 44780 4 DIGIT LCD DISPLAY 40 PIN with MAX controller hitachi 44780 P301 PDF

    LP4052

    Abstract: serial communication with AT89c2051 AT89C2051 PWM GENERATOR AT89C2051 microcontroller interrupt timer code Microcontroller AT89C2051 pin function AT89C2051 timer application AT89C2051 PROGRAMMING INTERFACE AT89c2051 Analog AT89C2051 microcontroller interrupt AT89C2051 internal memory map
    Text: Migrating from AT89C2051/C4051 to AT89LP2052/LP4052 New Features • • • • • • • • • • • • • • • • • 20 MIPS throughput at 20 MHz Clock Frequency and 2.7V, 85° C Operating Conditions Single Clock Cycle per Byte Fetch Serial Interface for Program Downloading


    Original     		AT89C2051/C4051 AT89LP2052/LP4052 32-byte 16-bit 3573B LP4052 serial communication with AT89c2051 AT89C2051 PWM GENERATOR AT89C2051 microcontroller interrupt timer code Microcontroller AT89C2051 pin function AT89C2051 timer application AT89C2051 PROGRAMMING INTERFACE AT89c2051 Analog AT89C2051 microcontroller interrupt AT89C2051 internal memory map PDF

    lcd interface with at89c2051

    Abstract: digital thermometer with atmel 8051 digital thermometer using 8051 AT89C2051 ic 8051 microcontroller thermometer LCD ASCII CODE c source code serial communication with AT89c2051 ATmel AT89C2051 AT89C2051 485 Thermometer clock LCD ic
    Text: A Digital Thermometer Using the AT89C2051 Microcontroller Introduction The system presented in this application note implements a simple digital thermometer that includes a built-in LCD and RS-485 communication port. It is designed around Atmel’s AT89C2051


    Original     		AT89C2051 RS-485 AT89C2051 DS1620 RS485 DS1620 lcd interface with at89c2051 digital thermometer with atmel 8051 digital thermometer using 8051 AT89C2051 ic 8051 microcontroller thermometer LCD ASCII CODE c source code serial communication with AT89c2051 ATmel AT89C2051 AT89C2051 485 Thermometer clock LCD ic PDF

    serial communication with AT89c2051

    Abstract: AT89C2051 internal RAM memory map AT89C2051 PROGRAMMING INTERFACE AT89C2051 internal memory map AT89C2051 microcontroller interrupt timer code AT89c2051 Application Note AT89C2051 microcontroller interrupt 8051 UART Program Examples AT89C2051 pin function Microcontroller AT89C2051 pin function
    Text: Migrating from AT89C2051/C4051 to AT89LP2052/LP4052 New Features • • • • • • • • • • • • • • • • • 20 MIPS throughput at 20 MHz Clock Frequency and 2.7V, 85°C Operating Conditions Single Clock Cycle per Byte Fetch Serial Interface for Program Downloading


    Original     		AT89C2051/C4051 AT89LP2052/LP4052 32-byte 16-bit serial communication with AT89c2051 AT89C2051 internal RAM memory map AT89C2051 PROGRAMMING INTERFACE AT89C2051 internal memory map AT89C2051 microcontroller interrupt timer code AT89c2051 Application Note AT89C2051 microcontroller interrupt 8051 UART Program Examples AT89C2051 pin function Microcontroller AT89C2051 pin function PDF

    SPPDF-01

    Abstract: AT89C2051 SN74CBTD3384 SPPDB-01 SPPDM-01 25-60B Microcontroller AT89C2051 C1116
    Text: SPPDF 01 Development Suite User’s Manual For SPPDM-01 FIR Filter Platform SPPDF 01 Development Suite User’s Manual Table of Contents Chapter I - Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page


    Original     		SPPDM-01 SPPFP-01, SPPFP-01 AT89C2051 SN74CBTD3384 MAX232AC RS232 C11-16 C17-18 0-100V SPPDF-01 SPPDB-01 25-60B Microcontroller AT89C2051 C1116 PDF

    11.0592 CRYSTAL used in microcontroller at89c52

    Abstract: AT89C51 Crystal oscillator 12 MHz 7 segment use at89c2051 AT89C51 INSTRUCTIONS SET 11.0592 CRYSTAL used in microcontroller at89c51 p AT89C51 INSTRUCTION SET 11.0592 CRYSTAL used in microcontroller at89c51 clock 7 segment use at89c2051 AT89C2051 internal RAM memory map Microcontroller - AT89C2051 pin diagram
    Text: The information presented in this chapter is collected from the Microcontroller Architectural Overview, AT89C51, AT89LV51, AT89C52, AT89LV52, AT89C2051, and AT89C1051 data sheets of this book. The material has been selected and rearranged to form a quick and convenient reference for the programmers of Atmel’s microcontroller family of devices. This guide pertains specifically to the AT89C51, AT89LV51,


    Original     		AT89C51, AT89LV51, AT89C52, AT89LV52, AT89C2051, AT89C1051 AT89LV52. 11.0592 CRYSTAL used in microcontroller at89c52 AT89C51 Crystal oscillator 12 MHz 7 segment use at89c2051 AT89C51 INSTRUCTIONS SET 11.0592 CRYSTAL used in microcontroller at89c51 p AT89C51 INSTRUCTION SET 11.0592 CRYSTAL used in microcontroller at89c51 clock 7 segment use at89c2051 AT89C2051 internal RAM memory map Microcontroller - AT89C2051 pin diagram PDF

    MICROCONTROLLER AT89C51 pin diagram

    Abstract: 11.0592 CRYSTAL used in microcontroller at89c51 11.0592 CRYSTAL used in microcontroller at89c52 7 segment use at89c51 AT89C51 INSTRUCTIONS SET Microcontroller AT89C2051 instruction set 2051 atmel clock 7 segment use at89c2051 flash programmer circuit for AT89c2051 AT89C51 INSTRUCTION SET
    Text: Memory Organization The information presented in this chapter is collected from the Microcontroller Architectural Overview, AT89C51, AT89LV51, AT89C52, AT89LV52, AT89C2051, and AT89C1051 data sheets of this book. The material has been selected and rearranged to form a quick and


    Original     		AT89C51, AT89LV51, AT89C52, AT89LV52, AT89C2051, AT89C1051 AT89LV52. MICROCONTROLLER AT89C51 pin diagram 11.0592 CRYSTAL used in microcontroller at89c51 11.0592 CRYSTAL used in microcontroller at89c52 7 segment use at89c51 AT89C51 INSTRUCTIONS SET Microcontroller AT89C2051 instruction set 2051 atmel clock 7 segment use at89c2051 flash programmer circuit for AT89c2051 AT89C51 INSTRUCTION SET PDF

    at89lp programmer

    Abstract: at89lp programmer interface serial communication with AT89c2051 Microcontroller AT89LP4052 AT89LP ATmel AT89C2051 lock bit AT89LP2052 AT89C2051 PROGRAMMING INTERFACE AT89C2051 MICRO CONTROLLER atmel 1010
    Text: AT89LP In-System Programming Specification 1. Overview The Atmel AT89LP microcontrollers feature 2K bytes to 64K bytes of on-chip Flash program memory. Some devices may also support Flash data memory. In-System Programming ISP allows programming and reprogramming of any AT89LP microcontroller positioned inside the end system. Using a simple 4-wire SPI interface, the


    Original     		AT89LP at89lp programmer at89lp programmer interface serial communication with AT89c2051 Microcontroller AT89LP4052 ATmel AT89C2051 lock bit AT89LP2052 AT89C2051 PROGRAMMING INTERFACE AT89C2051 MICRO CONTROLLER atmel 1010 PDF

    bootloader hex AT89C51

    Abstract: camera interface with at89s52 microcontroller Microcontroller AT89S52 OmniVision CMOS Camera Module rs232 Microcontroller AT89S52 40 pin serial communication at89s51 Microcontroller - AT89S51 ic at89c51 bootloader hex AT89C51 USB CONNECTOR AT89S51 programmer
    Text: Wireless Communications TMEBX741D Kit includes: • Antenna • 1 - Antenna Cable • 2-BNC Adapters • 1-25 to 9 Pin Parallel to Serial Cable • 1 - 25 to 9 Pin Adapter • 2 Coin Cells • 1 - Guide/Data Book • 3 - Floppys - Software TMEBX745B Kit includes:


    Original     		TMEBX741D TMEBX745B 868MHz 928MHz 310MHz 330MHz 429MHz 439MHz 902MHz bootloader hex AT89C51 camera interface with at89s52 microcontroller Microcontroller AT89S52 OmniVision CMOS Camera Module rs232 Microcontroller AT89S52 40 pin serial communication at89s51 Microcontroller - AT89S51 ic at89c51 bootloader hex AT89C51 USB CONNECTOR AT89S51 programmer PDF

    sandisk micro sd

    Abstract: digital clock using at89s52 microcontroller stepper motor control with avr application notes sandisk micro sd card pin configuration vhdl code for rs232 receiver STK 435 power amplifier Microcontroller AT89S52 vhdl code for ofdm Microcontroller AT89S52 40 pin fingerprint scanner circuit
    Text: Atmel Corporation Atmel Operations Corporate Headquarters 2325 Orchard Parkway San Jose, CA 95131 TEL 1 408 441-0311 FAX 1 (408) 487-2600 Memory 2325 Orchard Parkway San Jose, CA 95131 TEL 1 (408) 441-0311 FAX 1 (408) 436-4314 Regional Headquarters Microcontrollers


    Original     		CH-1705 3271B sandisk micro sd digital clock using at89s52 microcontroller stepper motor control with avr application notes sandisk micro sd card pin configuration vhdl code for rs232 receiver STK 435 power amplifier Microcontroller AT89S52 vhdl code for ofdm Microcontroller AT89S52 40 pin fingerprint scanner circuit PDF

    4052 Primer

    Abstract: AT89C2051 microcontroller interrupt source and its vector address 7 segment use at89c2051 clock 7 segment use at89c2051 AT89ISP atmel 8051 sample code AT89S52 INSTRUCTION SET Microcontroller - AT89s52 AT25C040 serial communication with AT89c2051
    Text: AT89LP2052/4052 Primer 1. Introduction The Atmel AT89LP2052/4052 microcontroller is a low-power, high-performance device featuring an enhanced single-cycle 8051 CPU, 2K/4K bytes of Flash memory, 256 bytes of RAM, configurable I/O, an analog comparator, dual pulse width modulation PWM outputs, a UART, a Serial Peripheral Interface (SPI) and a watchdog


    Original     		AT89LP2052/4052 AT89C2051/4051 AT89C2051document 4052 Primer AT89C2051 microcontroller interrupt source and its vector address 7 segment use at89c2051 clock 7 segment use at89c2051 AT89ISP atmel 8051 sample code AT89S52 INSTRUCTION SET Microcontroller - AT89s52 AT25C040 serial communication with AT89c2051 PDF

    AT90SC7272C

    Abstract: T5757 AVR atmega8515 led matrix AT78C5010 fingerprint scanner circuit ATSAM2193 STK502 voltage regulator Stepper motor control using AT89S52 STK502 voltage regulator ic atr0890
    Text: ATMEL PRODUCT GUIDE August 2004 Atmel Corporation • 2325 Orchard Parkway • San Jose, CA 95131 TEL: 408 441-0311 • FAX: (408) 487-2600 Web Site: http://www.atmel.com ATMEL’S PRODUCTS Atmel Corporation is an industry leader in the design and manufacture of advanced semiconductors, with focus on microcontrollers, nonvolatile memory, logic, radio frequency (RF) components and sensors. These functions are marketed as


    Original     		U6808B U6809B U6812B U6813B U6815BM U6820BM U7004B U7006B U9280M AT90SC7272C T5757 AVR atmega8515 led matrix AT78C5010 fingerprint scanner circuit ATSAM2193 STK502 voltage regulator Stepper motor control using AT89S52 STK502 voltage regulator ic atr0890 PDF

    GSM module Interface with At89s52

    Abstract: ATMEGA 16 AU dc motor control using ir remote by AT89C51 interface gps with AVR atmega128 SAM9733 servo motor atmega 12 volt dc motor speed control base on At89c51 "Radio Controlled Clock Receiver" ac motor AVR c source code for triac sam9793
    Text: ATMEL PRODUCT GUIDE APRIL 2002 Atmel Corporation • 2325 Orchard Parkway • San Jose, CA 95131 TEL: 408 441-0311 • FAX: (408) 487-2600 Web Site: http://www.atmel.com Atmel’s Products Atmel Corporation is a worldwide leader in the design, manufacturing and marketing of advanced semiconductors,


    Original     		U2896B. U6224B. U6239B. U3280M. U3600BM. U6268B. U641B. U3665M. U3666M. U642B. GSM module Interface with At89s52 ATMEGA 16 AU dc motor control using ir remote by AT89C51 interface gps with AVR atmega128 SAM9733 servo motor atmega 12 volt dc motor speed control base on At89c51 "Radio Controlled Clock Receiver" ac motor AVR c source code for triac sam9793 PDF

    RX3408

    Abstract: Radio fm circut HIMARK phase detector circut AT89C2051 PROGRAMMING INTERFACE AT89C2051 serial communication with AT89c2051 Design a Passive Low-pass Filter FM455E HiMARK Technology
    Text: RX3408 Low Power IF Receiver and PLL Frequency Synthesizer IC Advance Information HiMARK Technology, Inc. reserves the right to change the product described in this datasheet. All information contained in this datasheet is subject to change without prior notice. HiMARK Technology, Inc. assumes no responsibility


    Original     		RX3408 FM455E RX3408 Radio fm circut HIMARK phase detector circut AT89C2051 PROGRAMMING INTERFACE AT89C2051 serial communication with AT89c2051 Design a Passive Low-pass Filter FM455E HiMARK Technology PDF

    TH7852A

    Abstract: TH7890M TH7803A TH7890 AT93C56SC TH7802A VHDL code for ADC and DAC SPI with FPGA AT45DB021-SC CAMELIA 1.6M digital dice design of digital VHDL altera
    Text: R PRODUCT GUIDE October 2000 AT90 Series AVR 8-bit Microcontrollers Part Number Processor Description Availability AT90S1200 AVR AVR RISC, In-System Programmable Microcontroller with 1K Byte Flash and 64 Bytes EEPROM, 20-pin PDIP, 20-lead SOIC and 20-lead SSOP Packages


    Original     		AT90S1200 20-pin 20-lead AT90S2313 AT90S2323 AT90LS2323 10/00/35M TH7852A TH7890M TH7803A TH7890 AT93C56SC TH7802A VHDL code for ADC and DAC SPI with FPGA AT45DB021-SC CAMELIA 1.6M digital dice design of digital VHDL altera PDF

    at89c2051 architecture details

    Abstract: Microcontroller - AT89C2051 virtual machine Atmel - AT89C2051 Instruction sets AT89c2051 BASED FREQUENCY COUNTER Microcontroller AT89C2051 virtual machine Microcontroller - AT89C2051 instruction set lcd interface with at89c2051 REAL TIME CLOCK using AT89C2051 AT89C2051 microcontroller serial at89c2051
    Text: Using the AT89C2051 Microcontroller as a Virtual Machine It is often cited that what differentiates an embedded microcontroller from other general purpose computing devices is its integration into a larger electrical or electro-mechanical system. While this is


    Original     		AT89C2051 at89c2051 architecture details Microcontroller - AT89C2051 virtual machine Atmel - AT89C2051 Instruction sets AT89c2051 BASED FREQUENCY COUNTER Microcontroller AT89C2051 virtual machine Microcontroller - AT89C2051 instruction set lcd interface with at89c2051 REAL TIME CLOCK using AT89C2051 AT89C2051 microcontroller serial PDF

    ATA5722

    Abstract: ATAVRDRAGON AT97SC3204 tsop Ir sensor interface with atmega 16 atr0834t ATA5721 cd photo detector AT42QT4120 AT42QT5320 pc to pc communication using zigbee using AT89S52
    Text: ATMEL PRODUCT GUIDE Winter 2008 Atmel Corporation ● 2325 Orchard Parkway ● San Jose, CA 95131 TEL: 408 441-0311 ● FAX: (408) 487-2600 Web Site: http://www.atmel.com ATMEL PRODUCT GUIDE Winter 2008 ATMEL’S PRODUCTS Atmel Corporation is a global leader in the design and manufacture of microcontrollers, and complementary products such as


    Original     		PDF

    T5757

    Abstract: Microcontroller - AT89s52 connections with lcd Stepper motor control using AT89S52 DC MOTOR SPEED CONTROL SYSTEM USING AT89S52 MICRO AVR voltage regulator schematic using Triac hand dryer circuit using 8051 gsm modem interface AT89s51 mv silicon mp3 player usb sd card STK 439 Stereo amplifier GSM module Interface with At89s52
    Text: ATMEL PRODUCT GUIDE February 2005 Atmel Corporation • 2325 Orchard Parkway • San Jose, CA 95131 TEL: 408 441-0311 • FAX: (408) 487-2600 Web Site: http://www.atmel.com ATMEL’S PRODUCTS Atmel Corporation is a global leader in researching, designing, manufacturing and marketing advanced semiconductors,


    Original     		U2745B U479B U2766B U5020M U2790B U5021M U2793B U6032B U2794B U6043B T5757 Microcontroller - AT89s52 connections with lcd Stepper motor control using AT89S52 DC MOTOR SPEED CONTROL SYSTEM USING AT89S52 MICRO AVR voltage regulator schematic using Triac hand dryer circuit using 8051 gsm modem interface AT89s51 mv silicon mp3 player usb sd card STK 439 Stereo amplifier GSM module Interface with At89s52 PDF

    DR1200-DK

    Abstract: A3C9 5235 printer circuit diagram DR1201-DK DR1300-DK IC1000 ISO3309 ISO-3309 Microcontroller - AT89C2051 pin diagram DR1300
    Text: ASH Transceiver Software Designer’s Guide Updated 2002.08.07 ASH Transceiver Software Designer’s Guide 1 Introduction 1.1 Why Not Just Use a UART? 1.2 The Radio Channel – Magic and Imperfect 1.2.1 Modeling a radio system 1.2.2 Data rate and bandwidth


    Original     		IC1000 IC1000 swg19 DR1200-DK A3C9 5235 printer circuit diagram DR1201-DK DR1300-DK ISO3309 ISO-3309 Microcontroller - AT89C2051 pin diagram DR1300 PDF

    ACTIV8

    Abstract: flash programmer circuit for AT89c55 isp programmer circuit for AT89c2051 8051 microcontroller Assembly language program RF atmel 2051 Atmel 8051 Microcontrollers AVR182 40 pin 8051 programmer circuit 89S8252 HOW TO HEX FILE TO AT89C51 VIA RS232
    Text: RE E A BL W DA RM A FI GR P U Activ8r Combined Serial and Parallel Programmer for Atmel microcontrollers USER MANUAL Revision 1.03 Activ8r User Manual V1.03 Copyright Information Equinox guarantees that its products will be free from defects of material and


    Original     		PDF

    Atmel 89C51 microcontroller

    Abstract: Microcontroller - AT89C2051 pin diagram 8051 microcontroller free atmel 89C51 user manual microcontroller 89c51 pin diagram introduction to microcontroller 89C51 AT89S55 atmel 89C51 user guide atmel 8051 40-PIN AT 89C51 PLCC 44 pin
    Text: P le d ab el m e Fi m ar a w gr rd ro Ha State-of-the-art Device Programmer USER GUIDE Revision 1.04 Micro-Pro User Guide V1.04 Copyright Information Information in this document is subject to change without notice and does not represent a commitment on the part of the


    Original     		AT89C4051 AT89C51 AT89C52 AT89C55 AT89S8252 AT89S53 44-pin CAB-PAR25MM PSU-15250-UK, Atmel 89C51 microcontroller Microcontroller - AT89C2051 pin diagram 8051 microcontroller free atmel 89C51 user manual microcontroller 89c51 pin diagram introduction to microcontroller 89C51 AT89S55 atmel 89C51 user guide atmel 8051 40-PIN AT 89C51 PLCC 44 pin PDF