AVR Assembler 2 User's Guide
Contents
1. byte cseg csegsize db dd def device dq dseg dw elif else endif endm endmacro equ error eseg exit Lt ifdef ifndef include list listmac Macro message nolist OYg Set undef 8 Preprocessor AVR Assembler 2 0 Page 9 of 16 Revision BETA 3 2004 ATMEL Corp AIMEL The AVRASM2 preprocessor is an integrated part of the assembler handling C style preprocessor directives and the corresponding macro expansion A complete description of preprocessors is not given here a good user guide for the GNU C preprocessor is found here http www delorie com gnu docs gcec cpp_toc html The AVRASM2 preprocessor may largely be expected to work as described in this reference unless otherwise explicitly stated Note Preprocessor directives and macros are always case sensitive 8 1 Preprocessor directives The following preprocessor directives are implemented define undef ifdef ifndef if else elif fendif terror include pragma warning message defined above is the empty directive does nothing The defined keyword is only used in conjunction with if statements le if defined Not yet implemented concatenation stringification Will not be implemented line Note Only C style comments or are recognized by the preprocessor Attempting to use assembler comme2. 10 3 MaC OS sissssecscceccsccssesicsdecieeciccsesaucescecdsecvsessssedsaceuecevsesstessecusecesunsevecsccuesscsesessoissccvacsdeseseoeod TOA COMM ENS catorce O 11 OTHER NEW FEATURES 00 ica ip cris 15 11 1 Assembler A O LO 11 2 New AAA O LO 11 3 Built in known place for included files ccsscccssscccsscssssscsssssessssscscsssssssssesseee L 11 4 Motorola hex for large files aicisscscscevissccnsssessvessseschessncdevevonontusdonsasveessotekeasecanssestassecanscen L TES Nested Macro Calls TT AVR Assembler 2 0 Page 3 of 16 Revision BETA 3 2004 ATMEL Corp AIMEL 1 Introduction This document explains the difference between the new AVR Assembler 2 0 AVRASM2 and the current assembler AVRASM described in the AVR Studio on line help This information will be added to the on line help when AVRASM2 is officially released AVRASM2 is a complete re write of the AVR Assembler It is fully backwards compatible with version 1 x AVRASM with a few minor exceptions that are detailed in chapter 2 It also offers a number of new powerful features including e C style preprocessing directives like define ifdef etc This also includes the capability to control definition undefinition of preprocessor symbols and inclusion of files from the command line e Improved error detection and diagnostic messages including exceeding available SRAM and EEPROM memory ranges e Support for floating point constant expre
3. 2004 ATMEL Corp AIMEL 11 1 Assembler directives undef symbol Undefines a register definition created with the def directive Use this to avoid already defined by the DEF directive warnings dd expression expression dq expression expression These directives are similar to the dw directive except they are used to define doublewords 32 bit and quadwords 64 bit respectively The byte and word ordering is strictly little endian 11 2 New functions int Truncates a floating point expression to integer ie discards fractional part frac Extracts fractional part of a floating point expression ie discards integer part q7 Converts a fractional floating point expression to a form suitable for the FMUL FMULS FMULSU instructions sign 7 bit fraction qls Converts a fractional floating point to the form returned by the FMUL FMULS FMULSY instructions sign 15 bit fraction abs Returns the absolute value of a constant expression 11 3 Built in known place for included files Unlike AVRASM1 when AVRASM2 is installed as part of an AVR Studio installation it will know where the Appnotes include directory is and doesn t need to be told this via a command line option like I C Program Files Atmel AVR Tools AvrAssembler Appnotes 11 4 Motorola hex for large files Motorola hex S record output is now implemented for addresses above the 64kB limit 11 5 Nes
4. FG Generic hex format o ofile Put output in ofile d dfil Generate debug info for simulation in AVR Studio in dfile Can only be used with the f M I G option 1 lfile Generate listing in lfile m mfile Generate map in mfile e efile Place EEPROM contents in efile W Relative jumps are allowed to wrap for program ROM up to 4k words in size ignored C ver Specify AVR core version c Case sensitive 1 2 Turn on off AVR Assembler version 1 compatibility I dir Preprocessor Add dir to include search path i file Preprocessor Explicitly pre include file AVR Assembler 2 0 Page 6 of 16 Revision BETA 3 2004 ATMEL Corp AIMEL D name value Preprocessor Define symbol If value is omitted it is set to 1 U name Preprocessor Undefine symbol v verbosity 0 9 s vs Include target resource usage statistics vl Output low level assembly code to stdout v0 Silent only error messages printed vl Error and warning messages printed v2 Error warning and info messages printed default v3 v9 Unspecified increasing amounts of assembler internal dumps W Wrap relative jumps This option is obsoleted It is still recognized by the assembler but ignored The assembler will determine if wrapping is required based on flash memory size If the flash size is unknown wrap will be disabled C core version Specify AVR Core version The core version is n
5. db Hello n is equivalent to db os ee Tet L aM UET o ES A rn To create the equivalent to the C string Hello world n do as follows db Hello world n 0 9 7 Numeric constants C style integer constants dddd 00000 Oxhhhh are recognized as decimal octal and hexadecimal respectively Floating point constant formats are likewise according to C Additonally the forms hhhh and Obdddd are recognized as hexadecimal and binary integers respectively These forms are also recognized and evaluated by the preprocessor 10 Preprocessor and assembler interaction Some of the assembler and preprocessor features have very similar functions e g include conditionals and may interact in unexpected ways 10 1 Include include and include are identical except that include also supports the tinclude lt file gt form 10 2 Conditionals Preprocessor conditionals if etc relate to preprocessor symbols only defined with define or the D command line option Assembler conditional relate to both preprocessor and assembler symbols but beware of unexpected effects define FOO 2 ifdef FOO is a syntax error because the assembler will try to evaluate ifdef 2 Avoid mixing the two forms Preprocessor macros may be defined from the command line and this gives considerable flexibility 10 3 Macros Both the preprocessor and the assembler offer macros but they work very diffe
6. AIMEL AVR Assembler v 2 0 Addendum to on line help Beta 3 2004 07 07 AIMEL T ANTRODUCO O Noia ii 4 1 1 Intended ALIEN es asics sss cacesdsieacsusikcnsctasscssessescaseosaisdenadescancoutass cadssacaseossseasessancasecaseccseennes 4 1 2 SUP Id ia 4 2 PACKAGE CONTENTS naaa E a 4 3 INSTALLATION cocina 4 EA aros tico seoses roses ieo o oos sosis tiste SSS 5 E NEW CP o E A A 5 4 1 Changes in B ta Biss iescssvessnnsedccsusacscuaiedsanctacsavebanedaseasscsuvesevesddesonsacshbosedekeasutnssseiedeenssvenenesne 5 4 2 Changes in Beta Zeiss a cdi 5 5 KNOWN TS SUES voca ar anpara a aa Napa aaee vane cece encase ce ees 6 5 1 Broken include files and appmotes cccscccccsscsccssccscsscssssecscsesssssscsssssesscssssssssesseeseees 6 5 2 Comments in macro Call ini ro iaa rindan dear 6 6 INVOCATION S VNU AN iaa 6 7 AVR ASSEMBLER 2 SYNTAX 6 c cccc0c0cccccc cs scsceecdscndseccectesseeuetiecesectsesusessscnsndsesderes 8 Fab LIS CV WOES crass cc oousaeesusesscvosacsvexiosesustoceuasetsnssaedesstsauecssuedie Uapecasuale saute TEET EEE 8 A Seaeeudat a eaa a a a a a E R 8 TEZ HRC A a a A a a E E 9 7 1 3 Built in functions and Vari aDIGSs ri A 9 TL4 Ass mbler AIRE A A O Siu tA aah aera at 08 aan 9 9 PREPROCES SO Rio dais 9 O MA 10 8 2 Preprocessor directive OVO VIEW iss sdsccscocssbecssdeodasscnnndscgedsbodcsceoseseodsedeconsondndsedeadsoneieoncs 10 8 2 1 ING oa eas antes asc aanials T E dale ncaul usta a a A A tsbuedae 10 8 22 F
7. IMEL The AVRASM2 beta assembler will be installed and enabled by default The assembler is configured by selecting Project AVR Assembler Setup from the Studio menubar The upper part of this window is the same as for AVR Assembler 1 The lower part enables AVRASM2 Beta The Additional Parameters field is used to add additional command line parameters for AVRASM2 Hint Try adding vs see section 5 for explanation AYR Assembler E J Hex Output Format Intel intellec 8 MDS Intel hex y IV Create Map file Tl Create List file Z Wrap relative jumps Include File C Program FilestStmel WR T ools AvrAssembler AppNotes E AVF Assembler 2 JV Use AVR Assembler 2 0 Beta Additional Parameters 5 Cancel 3 1 Uninstallation This add on package cannot be uninstalled but unselecting Use AVR Assembler 2 0 beta above will have the same effect causing the standard 1 7x version to be used 4 What s New 4 1 Changes in Beta 3 Bugs fixed Macro argument expansion problem Preprocessor expression evaluation fails with multiple references to same macro Preprocessor stack overflow caused by indirectly self referencing macro Comments in define only work using C comments Documentation issue 4 2 Changes in Beta 2 Bugs fixed byte directive not allowed in eseg e Missing unclear error message when exceeding available SRAM EEPROM Argument propagation in nest
8. RT ADMIN PART NAME string pragma AVRPART CORE CORE VERSION version string pragma AVRPART CORE INSTRUCTIONS NOT SUPPORTED mnemonic operand operand pragma AVRPART CORE NEW INSTRUCTIONS mnemonic operand operand AVR Assembler 2 0 Page 11 of 16 Revision BETA 3 2004 ATMEL Corp AIMEL pragma AVRPART pragma AVRPART pragma AVRPART pragma AVRPART EMORY PROG FLASH size EMORY EEPROM size EMORY INT SRAM SIZE size EMORY INT SRAM START ADDR address See 8 Notes e The string values here are not quoted and that the numeric values must be pure numbers expressions or preprocessor macros not allowed here Everything in the pragma directive is case sensitive e Distinguishing between variants of the same instruction based on operands only works for instructions that are implemented with different operands in different variants on different AVR Core versions presently these are the d st and lpm instructions 8 4 Pre defined preprocessor macros __ AVRASM VERSION _ CORE VERSION _ DATE _ FILIE LINE PART NAME TIME _ Part dependent _ partname _ partname corresponds to the value of PART NAME above __ CORE coreversion__ coreversion corresponds to the value of CORE VERSION _ above 9 Other syntactic elements 9 1 Comments The following comment styles are recognized m 7 The rest of the line is a comment clas
9. UMING STs 5 asset cast ae Sassen Sentenced E asa O 10 Gch A A E ov cag neue E E EN E E E Tae 10 BA A e a 10 a E CU EEEE E E T ESEE 11 A E A EE E A E elawiuenalbecten manaresseannes 11 A a coer a e aa aeaa saan Ere a aM e ea io iai 11 8 2 8 CTOr FW Arno AMES E A SA 11 AVR Assembler 2 0 Page 2 of 16 Revision BETA 3 2004 ATMEL Corp AIMEL 8 29 PINCUS A A ia 11 A O ecpn ea cab ata rnin taboos 11 8 211 E empty AECI each atv tasecttunaadd vps cvilic ech couch hud cd nee ease nds bce E 11 8 3 LAMAS tia dl 8 4 Pre defined preprocessor MacrOS mmocoooonnonconccncnnccocanaconanonocanononnnonacanonacncconananonananacanonos 12 9 OTHER SYNTACTIC ELEMENTS si cccciiozoiannonncnani necnanocariccn acaricia cic conan noc ras 12 AS NTRA OMT PESPLOCE SOMO aii 12 9 2 DETI AAE CE carton EE ri lO 9 3 InStrUCHON Sii a 13 DA Label cda NOSTEXPESSION Si id LO 9 6 Strings and character CONStants scccccsccccssscsscsccscscccssssscsssssssccsssscssssscssssscssessssseeees 13 9 7 Numeric COMSTAIUS i ccccccccscessescosseccsatsscdessesecsocetiecdescoscctecateccdessesecsecatsessesoosecescebessdessesecseces 14 10 PREPROCESSOR AND ASSEMBLER INTERACTION ccsscsseeeeeeeeeesseeeees 14 TOT Ml ii inside ctbccdee devecdacedeucdbeseueesscesdscdue devesdodalensdde aveedeosseecdisduavsdessteecol 4 10 2 COmAitiOmal Sikes secccsecsecdccsccsesccsssedecsoscvecccbessescsescdensetedesscdescsesececdoosecssccoacesscessesoscsoceceeveosecse 1A
10. ed macro calls cause assembler to hang AVR Assembler 2 0 Page 5 of 16 Revision BETA 3 2004 ATMEL Corp AIMEL 5 Known issues This chapter lists known issues in AVR Assembler 2 0 release BETA 1 5 1 Broken include files and appnotes The issues mentioned in this section will be fixed in a later AVRASM2 release AVRASM2 may produce one or both of the following warnings depending on the device used tn2313def inc 123 warning Attempt to redefine keyword z ignored tn2313def inc 383 warning Attempt to redefine keyword or ignored These definitions the Zero Z flag in the status register and a deprecated flag in the UCSRA register use DOR instead of OR will be renamed removed from the inc files As the warnings state these definitions are ignored by AVRASM2 Any program not actually using these definitions will be fine Programs using these definitions cannot be assembled successfully and will need to be changed The reasons for these warnings are explained in section 6 1 5 2 Comments in macro calls There is a known bug causing syntax errors in some situations when C style comments are used in lines with macro calls 6 Invocation syntax The invocation syntax is shown below new options are bold and described below usage avrasm2 exe options file asm Options f O M I G E output file format fO Debug info for simulation in AVR Studio default fM Motorola hex fI Intel hex
11. eprocessor macros see below 9 4 Labels A label is a user symbol followed by a colon It may prepend an instruction or directive on the same line or be placed on a separate line 9 5 Expressions Constant expressions can be integer or floating point and follow the C rules for operator precedence and type propagation Symbols and instruction operands are always integer a suitable conversion function should be used to convert before assignment eg int q7 Implicit float int conversion cause a warning and the fractional part is discarded All C operators except are supported 9 6 Strings and character constants A string enclosed in double quotes can only be used in conjunction with the db directive The string is taken literally no escape sequences are recognized and it is not NUL terminated Character constants can be used anywhere an integer expression is allowed and the following C style escape sequences are recognized with the same meaning as in C n Newline ASCII LF 0x0a r Carriage return ASCI CR 0x0d a Alert bell ASCII BEL 0x07 b Backspace ASCII BS 0x08 AE Form feed ASCII FF 0x0c E Horizontal tab ASCII HT 0x09 v Vertical tab ASCII VT 0x0b AN Backslash 0 Null character ASCII NUL AVR Assembler 2 0 Page 13 of 16 Revision BETA 3 2004 ATMEL Corp AIMEL 000 ooo octal number and xhh hh hex number are also recognized Examples
12. er keywords will have the case shown here generally lower case 7 1 1 Instructions adc add adiw and andi asr pelr bld brbc brbs prec brcs break breg brge brhe brhs brid brie brlo brit brmi brne brpl brsh brtc brts brvc brvs bset bst Call cbi cbr Ele clh cli cln Gir cls clte clv ciz com cp cpe cpi cpse dec eicall eijmp elpm eor fmul fmuls fmulsu icall ijmp in inc jmp ld ldd ldi lds lpm AVR Assembler 2 0 Page 8 of 16 Revision BETA 3 2004 ATMEL Corp AIMEL isl lsr mov movw mul muls mulsu neg nop or ori out pop push reall ret reti rjmp rol ror sbc sbci sbi sbic sbis sbiw sbr sbre sbrs sec seh sei sen ser ses set sev sez sleep spm st std sts sub subi swap ESE wdr 7 1 2 Registers r8 r9 r10 r11 ri 113 114 r15 r16 rir r18 rl9 r20 r21 r22 r23 r24 r25 r26 r27 28 r29 r30 r31 X y Z 7 1 3 Built in functions and variables abs bytel byte2 byte3 byte4 exp2 frac high hwrd int log2 low lwrd page pc q15 q7 7 1 4 Assembler directives Assembler directives are recognized by the fact that they start with a period Any word preceded with a period will be attempted parsed as a directive There are no restrictions on the directive words without the leading period nothing prevents the user from defining symbols like if or byte The list of directives is given here for the sake of completeness not because the directives cause any problems
13. info messages are suppressed AVR Assembler 2 0 Page 7 of 16 Revision BETA 3 2004 ATMEL Corp AIMEL vl Print error and warning messages only info messages are suppressed v2 Print error warning and info messages This is the default behaviour HVS ait SVO Add increasing amounts of assembler internal status dump Mostly used for assembler debugging 7 AVR Assembler 2 Syntax 7 1 Keywords Unlike AVRASM1 keywords are reserved and cannot be redefined The example below shows a program using keyword redefinitions that are illegal in AVRASM2 EXAMPLE The following nonsensical and rather obfuscated program assembles without errors with AVRASM1 but is incorrect with AVRASM2 equ add 2 add is a keyword instruction def rl rl6 rl is a keyword register def r0 r31 r0 is a keyword register def r16 r24 rl6 is a keyword register def add r2 add is a keyword again instruction def mov r29 mov is a keyword instruction mov cpi r16 100 mov is a keyword again instruction H mov mov mov ldi mov mov mov rl add mov r0 rl rjmp mov This gets interesting not to mention this Which definition of add is used here Things are not what they seem Now what Ne Ne Ne Ne Se Ne Assembler keywords are recognized regardless of case unless the case sensitive option is used see section 5 If the case sensitive option is used assembl
14. nt syntax in preprocessor directives may give surprises 8 2 Preprocessor directive overview Only deviations from the C preprocessor are described here 8 2 1 define 1 define name value 2 define name arg value Note Variadic macros i e macros with variable number of arguments are not implemented 8 2 2 undef undef name 8 2 3 ifdef ifdef name 8 2 4 ifndef ifndef name AVR Assembler 2 0 Page 10 of 16 Revision BETA 3 2004 ATMEL Corp AIMEL 8 2 5 Hif Helif if condition elif condition The defined name operator is recognized in condition 8 2 6 else else 8 2 7 endif endif 8 2 8 error warning message terror tokens warning tokens message tokens Unlike the GNU C preprocessor the error warning and message directives will expand unquoted preprocessor macros Example message Part name PART NAME may produce the output Part name Atmega48 8 2 9 include 1 include file 2 include lt file gt Note Computed include is not implemented 1 e using a macro to specify an include file name 8 2 10 pragma pragma tokens See description below 8 2 11 empty directive 8 3 Pragmas Pragmas are used to specify part specific properties normally set up in include files Normally there is no reason to use pragmas in user programs The supported pragmas are pragma AVRPA
15. ormally specified in part definition files partdef inc this option is intended for testing of the assembler and generally not useful for end users c Causes the assembler to become entirely case sensitive Preprocessor directives and macros are always case sensitive Warning Setting this option will break many existing projects L 2 Enable and disable AVRASM1 compatibility mode As of BETA 1 this option is enabled by default warning about this is printed The default setting will be changed at a later time and this option may be removed altogether The compatibility mode will permit certain constructs otherwise considered errors reducing the risk of breaking existing projects i file Include a file include file directive is processed before the first source code line is processed Multiple 1 directives may be used and are processed in order D name value U name Define and undefine a preprocessor macro respectively Note that function type preprocessor macros may not be defined from the command line vs Print use statistics for register instruction and memory on standard output By default only the memory statistic is printed Note The full statistics will always be printed to the list file if one is specified vl This will print the raw instructions emitted to stdout after all symbolic info is replaced Mainly for assembler debugging purposes v0 Print error messages only warning and
16. rently and should not be intermixed AVR Assembler 2 0 Page 14 of 16 Revision BETA 3 2004 ATMEL Corp AIMEL The traditional assembler macro macro pushw push 0L push 0H endmacro Each line of the macro body remains a separate line after expansion Labels in the macro body have scope limited to the macro body Call of this macro looks like an instruction e g pushw z Preprocessor function style macros A corresponding preprocessor macro would be define pushw wreg A push wreg L push wreg H Note the preprocessor concatenation operator is not yet implemented in BETA 1 Labels defined in a preprocessor macro have global scope and the entire macro body becomes one single line after expansion It is called like a function e g pushw z It is generally not recommended to use preprocessor macros in this fashion Preprocessor macros are best suited for implementing constant expressions e g define square x x x 10 4 Comments The preprocessor only recognizes C style comments Assembler comments should not be used in conjunction with preprocessor directives If assembler comments are used in conjunction with define directives the comment will become part of the macro which may cause surprises when the macro is expanded 11 Other new features The following minor new features are also introduced AVR Assembler 2 0 Page 15 of 16 Revision BETA 3
17. sic assembler comments Like the rest of the line is a comment Block comment th nclosed text is a comment may span multiple lines This style of comments cannot be nested 9 1 1 Preprocessor note The preprocessor only recognizes C style comments The semicolon is not treated in any special way in preprocessor directives and this may have unexpected effects To avoid surprises C style comments should be used exclusively in lines with prepocessor directives Examle define FOO 42 The foobaristic constant define BAR 43 This is a bar plain and simple These definitions will result in FOO having the value 42 The foobaristic constant while BAR simply has the value 43 This may or may not be a problem depending on how FOO is used AVR Assembler 2 0 Page 12 of 16 Revision BETA 3 2004 ATMEL Corp AIMEL 9 2 User symbols User symbols may consist of letters a z A Z digits 0 9 and underscore _ The first character cannot be a digit and keywords are reserved 9 3 Instructions Instructions take the following forms mnemonic mnemonic operand mnemonic operand operand2 Allowed operands are registers r0 r31 x y Z X y Z X y z and integer expressions including preprocessor macros constants defined with assembler directives labels and functions Multiple instructions in a single line is allowed but not recommended It is supported to faciliate pr
18. ssions and conversion to fractional numbers as used with the FMUL FMUS FMULSU instructions e Resource use statistics including instructions registers and memory e Externalizing of device support meaning support for new devices may be added without having to upgrade the assembler executable AVRASM2 is intended to replace v 1 x completely but will be offered as an alternative during a test period to allow a painless transition between the two versions 1 1 Intended Audience This document is written for existing users of AVR Studio 4 AVR Assembler and assumes some familiarity with the AVR architecture and AVR Assembler 1 x AVRASM1 syntax The AVR instruction set and AVRASMI syntax are documented in the AVR Studio Online Help 1 2 Support This is a BETA release and as such not supported via the normal ATMEL support channels However users may send feedback and bug reports directly to the developers using the e mail address avrbeta atmel com The AVR Studio 4 forum at http www avrfreaks com is also a suitable channel for providing feedback or discussing this release 2 Package contents The following files are found at the download site AvrAsm2 Addendum pdf This file README AvrAsm2 txt README file AvrAssembler2 exe Installation program 3 Installation Download the file AvrAssembler2 exe run it and follow instructions AVR Assembler 2 0 Page 4 of 16 Revision BETA 3 O 2004 ATMEL Corp A
19. ted macro calls Unlike AVRASM1 nested macro calls are supported Use of this feature is not recommended as it is very easy to lose track of what s going on Nested macro definitions are not allowed AVR Assembler 2 0 Page 16 of 16 Revision BETA 3 2004 ATMEL Corp
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