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LCD DRIVER FOR HD44780 #2
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LCD DRIVER FOR HD44780 AND 2313

                                    ;*************************************************************** 
                                    ;Programm LCD.ASM 
                                    ;Das Programm demonstriert, wie man eine LCD-Anzeige mit 
                                    ;16 Zeichen x 2 Zeilen an einen AT90S2313 anschliesst. 
                                    ;Es wird vorausgesetzt, dass die Anzeige einen HD44780 oder 
                                    ;kompatiblen Controller verwendet. 
                                    ;AT90S2313 mit 4 MHz Takt 
                                    ;*************************************************************** 
                                    
                                    .device AT90S2313 
                                    .include "2313def.inc" ;muss im selben 
                                    ;Verzeichnis stehen 
                                    
                                    
                                    ;Definition der Steuerleitungen 
                                    .equ E = PD0 ;E an Pin PD0 
                                    .equ RW = PD1 ;RW an Pin PD1 
                                    .equ RS = PD2 ;RS an Pin PD2 
                                    ;.equ LCD_cntr = PORTD ;PORTD ist Kontroll-Port 
                                    ;.equ LCD_data = PORTB ;PORTB ist Daten-Port 
                                    .equ BF = PB7 ;Busy flag 
                                    
                                    
                                    ;LCD Befehle 
                                    .equ clear_LCD = 0b00000001 ;loesche Anzeige 
                                    .equ home_LCD = 0b00000010 ;return home 
                                    .equ set_LCD = 0b00111000 ;8 bits,2 Zeilen,5x7dots 
                                    .equ LCD_on = 0b00001110 ;schalte LCD ein 
                                    .equ entry_mode = 0b00000110 ;setze Cursor 
                                    
                                    
                                    ;Variablendefinition 
                                    
                                    .def zeichen = r0 ;Zeichen aus der Tabelle 
                                    .def buffer = r16 ;RX/TX Daten von/zu LCD 
                                    .def counter = r17 ;Zaehler fuer den Text 
                                    .def temp = r18 
                                    
                                    
                                    .CSEG 
                                    .ORG 0x00 ; Programm beginnt bei 0 
                                    rjmp main ; Starte Hauptprogramm 
                                    
                                    ;************************************************************** 
                                    ; Subroutine init 
                                    ; Initialisiere PORTD 
                                    ;************************************************************** 
                                    
                                    init: ldi temp,0b11111111 ;PORTD ist Ausgang 
                                    out DDRD,temp 
                                    cbi PORTD,E ;E initialisieren 
                                    cbi PORTD,RS 
                                    cbi PORTD,RW 
                                    ret 
                                    
                                    
                                    
                                    ;*************************************************************** 
                                    ; Subroutine busy_flag 
                                    ; Diese Routine testet, ob die LCD-Anzeige bereit ist, einen 
                                    ; neuen Befehl oder weitere Daten zu empfangen. 
                                    ;*************************************************************** 
                                    
                                    busy_flag: ldi temp,0b00000000 ;PORTB ist Eingang 
                                    out DDRB,temp 
                                    cbi PORTD,RS ;Befehl wird gesendet 
                                    sbi PORTD,RW ;setze LCD in Lesemodus 
                                    sbi PORTD,E ;spreche LCD an 
                                    nop 
                                    nop 
                                    sbic PINB,BF ;LCD bereit? 
                                    rjmp busy_flag ;nein, wiederhole 
                                    cbi PORTD,E ;disable LCD 
                                    ret ;LCD bereit 
                                    
                                    
                                    ;*************************************************************** 
                                    ; Subroutine write_data 
                                    ; Diese Routine sendet Daten zur LCD-Anzeige. 
                                    ; Die Daten muessen im Register buffer uebergeben werden. 
                                    ;*************************************************************** 
                                    
                                    write_data: rcall busy_flag ;LCD bereit? 
                                    ldi temp,0b11111111 ;PORTB ist Ausgang 
                                    out DDRB,temp 
                                    sbi PORTD,RS ;Daten werden gesendet 
                                    cbi PORTD,RW ;LCD in Schreibmodus 
                                    sbi PORTD,E ;spreche LCD an 
                                    out PORTB,buffer ;sende Daten 
                                    cbi PORTD,E ;disable LCD 
                                    ret 
                                    
                                    
                                    ;*************************************************************** 
                                    ; Subroutine write_instr 
                                    ; Diese Routine sendet Befehle zur LCD-Anzeige. 
                                    ; Der Befehl muss im Register buffer uebergeben werden. 
                                    ;*************************************************************** 
                                    
                                    write_instr: rcall busy_flag ;LCD bereit? 
                                    ldi temp,0b11111111 ;RB ist Ausgang 
                                    out DDRB,temp 
                                    cbi PORTD,RS ;Befehl wird gesendet 
                                    cbi PORTD,RW ;LCD in Schreibmodus 
                                    sbi PORTD,E ;spreche LCD an 
                                    out PORTB,buffer ;sende Befehl 
                                    cbi PORTD,E ;disable LCD 
                                    ret 
                                    
                                    
                                    ;*************************************************************** 
                                    ; Hauptprogramm 
                                    ; Schreibt "AT90S2313" in die erste Zeile und "LCD-Routine" 
                                    ; in die zweite Zeile des LCDs. 
                                    ;*************************************************************** 
                                    
                                    main: ldi temp,RAMEND ; setze Stack-Pointer 
                                    out SPL,temp ; an das SRAM-Ende 
                                    
                                    rcall init ; PORTD initialisieren 
                                    
                                    ldi buffer,set_LCD ;setze LCD Funktion 
                                    rcall write_instr 
                                    
                                    ldi buffer,LCD_on ;schalte LCD ein 
                                    rcall write_instr 
                                    
                                    ldi buffer,clear_LCD ;loesche Anzeige 
                                    rcall write_instr 
                                    
                                    ldi buffer,entry_mode ;Eingabemodus 
                                    rcall write_instr 
                                    
                                    
                                    ;Holt den Text 'AT90S2313' aus der Tabelle und schreibt diesen in 
                                    ;die erste Zeile der Anzeige 
                                    
                                    ldi counter,9 ;Zeichenzaehler 
                                    ldi ZL,LOW(Tabelle1*2) ;Low-Zeiger auf Tabellenanfang 
                                    ldi ZH,HIGH(Tabelle1*2) ;High-Zeiger auf Tabellenanfang 
                                    loop_msg1: lpm ;hole Zeichen aus Tabelle 
                                    mov buffer,zeichen ;Zeichen uebergeben 
                                    rcall write_data ;schreibe Zeichen in LCD 
                                    adiw ZL+1 ;16-Bit Zeiger erhoehen 
                                    dec counter ;alle Zeichen gesendet? 
                                    brne loop_msg1 ;Nein! Sende naechstes Zeichen 
                                    
                                    
                                    ;Holt den Text 'LCD-Routine' aus der Tabelle und schreibt diesen 
                                    ;in die zweite Zeile der Anzeige 
                                    
                                    ldi buffer,0b11000000 ;LCD-Startadresse 2.Zeile 
                                    rcall write_instr ;sende Befehl 
                                    ldi counter,11 ;Zeichenzaehler 
                                    ldi ZL,LOW(Tabelle2*2) ;Low-Zeiger auf Tabellenanfang 
                                    ldi ZH,HIGH(Tabelle2*2) ;High-Zeiger auf Tabellenanfang 
                                    loop_msg2: lpm ;hole Zeichen aus Tabelle 
                                    mov buffer,zeichen ;Zeichen uebergeben 
                                    rcall write_data ;schreibe Zeichen in LCD 
                                    adiw ZL+1 ;16-Bit Zeiger erhoehen 
                                    no_carry2: dec counter ;alle Zeichen gesendet? 
                                    brne loop_msg2 ;Nein! Sende naechstes Zeichen 
                                    
                                    
                                    
                                    ;Endlosschleife. AVR zuruecksetzen, um Programm erneut zu starten 
                                    
                                    loop: rjmp loop 
                                    
                                    
                                    ;Tabelle 1 mit dem Text "AT90S2313", der in die 1.Zeile geschrieben 
                                    ;werden soll 
                                    
                                    Tabelle1: .DB "AT90S2313" 
                                    
                                    
                                    ;Tabelle 2 mit dem Text "LCD-Routine", der in die 2.Zeile geschrieben 
                                    ;werden soll 
                                    
                                    Tabelle2: .DB "LCD-Routine"
                                    
                                 

Programming the AVR Microcontrollers in Assember Machine Language

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Atmel AVR From Wikipedia, the free encyclopedia (Redirected from Avr) Jump to: navigation, search The AVRs are a family of RISC microcontrollers from Atmel. Their internal architecture was conceived by two students: Alf-Egil Bogen and Vegard Wollan, at the Norwegian Institute of Technology (NTH] and further developed at Atmel Norway, a subsidiary founded by the two architects. Atmel recently released the Atmel AVR32 line of microcontrollers. These are 32-bit RISC devices featuring SIMD and DSP instructions, along with many additional features for audio and video processing, intended to compete with ARM based processors. Note that the use of "AVR" in this article refers to the 8-bit RISC line of Atmel AVR Microcontrollers. The acronym AVR has been reported to stand for Advanced Virtual RISC. It's also rumoured to stand for the company's founders: Alf and Vegard, who are evasive when questioned about it. Contents [hide] 1 Device Overview 1.1 Program Memory 1.2 Data Memory and Registers 1.3 EEPROM 1.4 Program Execution 1.5 Speed 2 Development 3 Features 4 Footnotes 5 See also 6 External Links 6.1 Atmel Official Links 6.2 AVR Forums & Discussion Groups 6.3 Machine Language Development 6.4 C Language Development 6.5 BASIC & Other AVR Languages 6.6 AVR Butterfly Specific 6.7 Other AVR Links [edit] Device Overview The AVR is a Harvard architecture machine with programs and data stored and addressed separately. Flash, EEPROM, and SRAM are all integrated onto a single die, removing the need for external memory (though still available on some devices). [edit] Program Memory Program instructions are stored in semi-permanent Flash memory. Each instruction for the AVR line is either 16 or 32 bits in length. The Flash memory is addressed using 16 bit word sizes. The size of the program memory is indicated in the naming of the device itself. For instance, the ATmega64x line has 64Kbytes of Flash. Almost all AVR devices are self-programmable. [edit] Data Memory and Registers The data address space consists of the register file, I/O registers, and SRAM. The AVRs have thirty-two single-byte registers and are classified as 8-bit RISC devices. The working registers are mapped in as the first thirty-two memory spaces (000016-001F16) followed by the 64 I/O registers (002016-005F16). The actual usable RAM starts after both these sections (address 006016). (Note that the I/O register space may be larger on some more extensive devices, in which case memory mapped I/O registers will occupy a portion of the SRAM.) Even though there are separate addressing schemes and optimized opcodes for register file and I/O register access, all can still be addressed and manipulated as if they were in SRAM. [edit] EEPROM Almost all devices have on-die EEPROM. This is most often used for long-term parameter storage to be retrieved even after cycling the power of the device. [edit] Program Execution Atmel's AVRs have a single level pipeline design. The next machine instruction is fetched as the current one is executing. Most instructions take just one or two clock cycles, making AVRs relatively fast among the eight-bit microcontrollers. The AVR family of processors were designed for the efficient execution of compiled C code. The AVR instruction set is more orthogonal than most eight-bit microcontrollers, however, it is not completely regular: Pointer registers X, Y, and Z have addressing capabilities that are different from each other. Register locations R0 to R15 have different addressing capabilities than register locations R16 to R31. I/O ports 0 to 31 have different addressing capabilities than I/O ports 32 to 63. CLR affects flags, while SER does not, even though they are complementary instructions. CLR set all bits to zero and SER sets them to one. (Note though, that neither CLR nor SER are native instructions. Instead CLR is syntactic sugar for [produces the same machine code as] EOR R,R while SER is syntactic sugar for LDI R,$FF. Math operations such as EOR modify flags while moves/loads/stores/branches such as LDI do not.) [edit] Speed The AVR line can normally support clock speeds from 0-16MHz, with some devices reaching 20MHz. Lower powered operation usually requires a reduced clock speed. All AVRs feature an on-chip oscillator, removing the need for external clocks or resonator circuitry. Because many operations on the AVR are single cycle, the AVR can achieve up to 1MIPS per MHz. [edit] Development AVRs have a large following due to the free and inexpensive development tools available, including reasonably priced development boards and free development software. The AVRs are marketed under various names that share the same basic core but with different peripheral and memory combinations. Some models (notably, the ATmega range) have additional instructions to make arithmetic faster. Compatibility amongst chips is fairly good. See external links for sites relating to AVR development. [edit] Features Current AVRs offer a wide range of features: RISC Core Running Many Single Cycle Instructions Multifunction, Bi-directional I/O Ports with Internal, Configurable Pull-up Resistors Multiple Internal Oscillators Internal, Self-Programmable Instruction Flash Memory up to 256K In-System Programmable using ICSP, JTAG, or High Voltage methods Optional Boot Code Section with Independent Lock Bits for Protection Internal Data EEPROM up to 4KB Internal SRAM up to 8K 8-Bit and 16-Bit Timers PWM Channels & dead time generator Lighting (PWM Specific) Controller models Dedicated IC Compatible Two-Wire Interface (TWI) Synchronous/Asynchronous Serial Peripherals (UART/USART) (As used with RS-232,RS-485, and more) Serial Peripheral Interface (SPI) CAN Controller Support USB Controller Support Proper High-speed hardware & Hub controller with embedded AVR. Also freely available low-speed (HID) software emulation Ethernet Controller Support Universal Serial Interface (USI) for Two or Three-Wire Synchronous Data Transfer Analog Comparators LCD Controller Support 10-Bit A/D Converters, with multiplex of up to 16 channels Brownout Detection Watchdog Timer (WDT) Low-voltage Devices Operating Down to 1.8v Multiple Power-Saving Sleep Modes picoPower Devices Atmel AVR assembler programming language Atmel AVR machine programming language Atmel AVR From Wikipedia, the free encyclopedia (Redirected from Avr) Jump to: navigation, search The AVRs are a family of RISC microcontrollers from Atmel. Their internal architecture was conceived by two students: Alf-Egil Bogen and Vegard Wollan, at the Norwegian Institute of Technology (NTH] and further developed at Atmel Norway, a subsidiary founded by the two architects. Atmel recently released the Atmel AVR32 line of microcontrollers. These are 32-bit RISC devices featuring SIMD and DSP instructions, along with many additional features for audio and video processing, intended to compete with ARM based processors. Note that the use of "AVR" in this article refers to the 8-bit RISC line of Atmel AVR Microcontrollers. The acronym AVR has been reported to stand for Advanced Virtual RISC. It's also rumoured to stand for the company's founders: Alf and Vegard, who are evasive when questioned about it. Contents [hide] 1 Device Overview 1.1 Program Memory 1.2 Data Memory and Registers 1.3 EEPROM 1.4 Program Execution 1.5 Speed 2 Development 3 Features 4 Footnotes 5 See also 6 External Links 6.1 Atmel Official Links 6.2 AVR Forums & Discussion Groups 6.3 Machine Language Development 6.4 C Language Development 6.5 BASIC & Other AVR Languages 6.6 AVR Butterfly Specific 6.7 Other AVR Links [edit] Device Overview The AVR is a Harvard architecture machine with programs and data stored and addressed separately. Flash, EEPROM, and SRAM are all integrated onto a single die, removing the need for external memory (though still available on some devices). [edit] Program Memory Program instructions are stored in semi-permanent Flash memory. Each instruction for the AVR line is either 16 or 32 bits in length. The Flash memory is addressed using 16 bit word sizes. The size of the program memory is indicated in the naming of the device itself. For instance, the ATmega64x line has 64Kbytes of Flash. Almost all AVR devices are self-programmable. [edit] Data Memory and Registers The data address space consists of the register file, I/O registers, and SRAM. The AVRs have thirty-two single-byte registers and are classified as 8-bit RISC devices. The working registers are mapped in as the first thirty-two memory spaces (000016-001F16) followed by the 64 I/O registers (002016-005F16). The actual usable RAM starts after both these sections (address 006016). (Note that the I/O register space may be larger on some more extensive devices, in which case memory mapped I/O registers will occupy a portion of the SRAM.) Even though there are separate addressing schemes and optimized opcodes for register file and I/O register access, all can still be addressed and manipulated as if they were in SRAM. [edit] EEPROM Almost all devices have on-die EEPROM. This is most often used for long-term parameter storage to be retrieved even after cycling the power of the device. [edit] Program Execution Atmel's AVRs have a single level pipeline design. The next machine instruction is fetched as the current one is executing. Most instructions take just one or two clock cycles, making AVRs relatively fast among the eight-bit microcontrollers. The AVR family of processors were designed for the efficient execution of compiled C code. The AVR instruction set is more orthogonal than most eight-bit microcontrollers, however, it is not completely regular: Pointer registers X, Y, and Z have addressing capabilities that are different from each other. Register locations R0 to R15 have different addressing capabilities than register locations R16 to R31. I/O ports 0 to 31 have different addressing capabilities than I/O ports 32 to 63. CLR affects flags, while SER does not, even though they are complementary instructions. CLR set all bits to zero and SER sets them to one. (Note though, that neither CLR nor SER are native instructions. Instead CLR is syntactic sugar for [produces the same machine code as] EOR R,R while SER is syntactic sugar for LDI R,$FF. Math operations such as EOR modify flags while moves/loads/stores/branches such as LDI do not.) [edit] Speed The AVR line can normally support clock speeds from 0-16MHz, with some devices reaching 20MHz. Lower powered operation usually requires a reduced clock speed. All AVRs feature an on-chip oscillator, removing the need for external clocks or resonator circuitry. Because many operations on the AVR are single cycle, the AVR can achieve up to 1MIPS per MHz. [edit] Development AVRs have a large following due to the free and inexpensive development tools available, including reasonably priced development boards and free development software. The AVRs are marketed under various names that share the same basic core but with different peripheral and memory combinations. Some models (notably, the ATmega range) have additional instructions to make arithmetic faster. Compatibility amongst chips is fairly good. See external links for sites relating to AVR development. [edit] Features Current AVRs offer a wide range of features: RISC Core Running Many Single Cycle Instructions Multifunction, Bi-directional I/O Ports with Internal, Configurable Pull-up Resistors Multiple Internal Oscillators Internal, Self-Programmable Instruction Flash Memory up to 256K In-System Programmable using ICSP, JTAG, or High Voltage methods Optional Boot Code Section with Independent Lock Bits for Protection Internal Data EEPROM up to 4KB Internal SRAM up to 8K 8-Bit and 16-Bit Timers PWM Channels & dead time generator Lighting (PWM Specific) Controller models Dedicated IC Compatible Two-Wire Interface (TWI) Synchronous/Asynchronous Serial Peripherals (UART/USART) (As used with RS-232,RS-485, and more) Serial Peripheral Interface (SPI) CAN Controller Support USB Controller Support Proper High-speed hardware & Hub controller with embedded AVR. Also freely available low-speed (HID) software emulation Ethernet Controller Support Universal Serial Interface (USI) for Two or Three-Wire Synchronous Data Transfer Analog Comparators LCD Controller Support 10-Bit A/D Converters, with multiplex of up to 16 channels Brownout Detection Watchdog Timer (WDT) Low-voltage Devices Operating Down to 1.8v Multiple Power-Saving Sleep Modes picoPower Devices Atmel AVR assembler programming language Atmel AVR machine programming language Atmel AVR From Wikipedia, the free encyclopedia (Redirected from Avr) Jump to: navigation, search The AVRs are a family of RISC microcontrollers from Atmel. Their internal architecture was conceived by two students: Alf-Egil Bogen and Vegard Wollan, at the Norwegian Institute of Technology (NTH] and further developed at Atmel Norway, a subsidiary founded by the two architects. Atmel recently released the Atmel AVR32 line of microcontrollers. These are 32-bit RISC devices featuring SIMD and DSP instructions, along with many additional features for audio and video processing, intended to compete with ARM based processors. Note that the use of "AVR" in this article refers to the 8-bit RISC line of Atmel AVR Microcontrollers. The acronym AVR has been reported to stand for Advanced Virtual RISC. It's also rumoured to stand for the company's founders: Alf and Vegard, who are evasive when questioned about it. Contents [hide] 1 Device Overview 1.1 Program Memory 1.2 Data Memory and Registers 1.3 EEPROM 1.4 Program Execution 1.5 Speed 2 Development 3 Features 4 Footnotes 5 See also 6 External Links 6.1 Atmel Official Links 6.2 AVR Forums & Discussion Groups 6.3 Machine Language Development 6.4 C Language Development 6.5 BASIC & Other AVR Languages 6.6 AVR Butterfly Specific 6.7 Other AVR Links [edit] Device Overview The AVR is a Harvard architecture machine with programs and data stored and addressed separately. Flash, EEPROM, and SRAM are all integrated onto a single die, removing the need for external memory (though still available on some devices). [edit] Program Memory Program instructions are stored in semi-permanent Flash memory. Each instruction for the AVR line is either 16 or 32 bits in length. The Flash memory is addressed using 16 bit word sizes. The size of the program memory is indicated in the naming of the device itself. For instance, the ATmega64x line has 64Kbytes of Flash. Almost all AVR devices are self-programmable. [edit] Data Memory and Registers The data address space consists of the register file, I/O registers, and SRAM. The AVRs have thirty-two single-byte registers and are classified as 8-bit RISC devices. The working registers are mapped in as the first thirty-two memory spaces (000016-001F16) followed by the 64 I/O registers (002016-005F16). The actual usable RAM starts after both these sections (address 006016). (Note that the I/O register space may be larger on some more extensive devices, in which case memory mapped I/O registers will occupy a portion of the SRAM.) Even though there are separate addressing schemes and optimized opcodes for register file and I/O register access, all can still be addressed and manipulated as if they were in SRAM. [edit] EEPROM Almost all devices have on-die EEPROM. This is most often used for long-term parameter storage to be retrieved even after cycling the power of the device. [edit] Program Execution Atmel's AVRs have a single level pipeline design. The next machine instruction is fetched as the current one is executing. Most instructions take just one or two clock cycles, making AVRs relatively fast among the eight-bit microcontrollers. The AVR family of processors were designed for the efficient execution of compiled C code. The AVR instruction set is more orthogonal than most eight-bit microcontrollers, however, it is not completely regular: Pointer registers X, Y, and Z have addressing capabilities that are different from each other. Register locations R0 to R15 have different addressing capabilities than register locations R16 to R31. I/O ports 0 to 31 have different addressing capabilities than I/O ports 32 to 63. CLR affects flags, while SER does not, even though they are complementary instructions. CLR set all bits to zero and SER sets them to one. (Note though, that neither CLR nor SER are native instructions. Instead CLR is syntactic sugar for [produces the same machine code as] EOR R,R while SER is syntactic sugar for LDI R,$FF. Math operations such as EOR modify flags while moves/loads/stores/branches such as LDI do not.) [edit] Speed The AVR line can normally support clock speeds from 0-16MHz, with some devices reaching 20MHz. Lower powered operation usually requires a reduced clock speed. All AVRs feature an on-chip oscillator, removing the need for external clocks or resonator circuitry. Because many operations on the AVR are single cycle, the AVR can achieve up to 1MIPS per MHz. [edit] Development AVRs have a large following due to the free and inexpensive development tools available, including reasonably priced development boards and free development software. The AVRs are marketed under various names that share the same basic core but with different peripheral and memory combinations. Some models (notably, the ATmega range) have additional instructions to make arithmetic faster. Compatibility amongst chips is fairly good. See external links for sites relating to AVR development. [edit] Features Current AVRs offer a wide range of features: RISC Core Running Many Single Cycle Instructions Multifunction, Bi-directional I/O Ports with Internal, Configurable Pull-up Resistors Multiple Internal Oscillators Internal, Self-Programmable Instruction Flash Memory up to 256K In-System Programmable using ICSP, JTAG, or High Voltage methods Optional Boot Code Section with Independent Lock Bits for Protection Internal Data EEPROM up to 4KB Internal SRAM up to 8K 8-Bit and 16-Bit Timers PWM Channels & dead time generator Lighting (PWM Specific) Controller models Dedicated IC Compatible Two-Wire Interface (TWI) Synchronous/Asynchronous Serial Peripherals (UART/USART) (As used with RS-232,RS-485, and more) Serial Peripheral Interface (SPI) CAN Controller Support USB Controller Support Proper High-speed hardware & Hub controller with embedded AVR. Also freely available low-speed (HID) software emulation Ethernet Controller Support Universal Serial Interface (USI) for Two or Three-Wire Synchronous Data Transfer Analog Comparators LCD Controller Support 10-Bit A/D Converters, with multiplex of up to 16 channels Brownout Detection Watchdog Timer (WDT) Low-voltage Devices Operating Down to 1.8v Multiple Power-Saving Sleep Modes picoPower Devices Atmel AVR assembler programming language Atmel AVR machine programming language