Post by thread:sublw

Hi everybody, I was away for a while, but I am now back. Don't matter, nobody knew me...:( I am back because I need your help. I have an ASM file that contains: sublw .3 and it is not working properly. When I am replacing it with addlw 0xFD, everything is working! I though the assembler was translating a sublw into the right addlw?! Is it the same opcode? Another BIG problem: I am reading a byte 0xAD in EEPROM, with: EEREAD bsf STATUS,RP0 bsf EECON1,RD bcf STATUS,RP0 movf EEDATA,w return In my main program I am doing the following code: call EEREAD btfsc w,2 goto OK .... OK "Send to LCD that I have been here" The problem is that I never go to OK!!! BUT when doing the following: call EEREAD btfsc EEREAD,2 goto OK .... OK "Send to LCD that I have been here" Everithing is working! I really don't understand what's happening! Please ... help me. David

Hello David . > Hi everybody, > I was away for a while, but I am now back. Don't matter, nobody knew me...:( Don't cry i remember you. ;) > I am back because I need your help. I have an ASM file that contains: > > sublw .3 > > and it is not working properly. When I am replacing it with addlw 0xFD, > everything is working! I though the assembler was translating a sublw > into the right addlw?! Is it the same opcode? David, look carefully in your PIC manual. I think you will be surprised because sublw K mean K-W result to W not W-K as you think ! But addlw -K works as you expect: W-K result to W . It's the Greate Microchip joke . ;))) WBR Dmitry.

Hi Dave, > I was away for a while, but I am now back. Don't matter, nobody knew >me...:( We're glad you're back anyways... > I am back because I need your help. I have an ASM file that contains: > > sublw .3 > >and it is not working properly. When I am replacing it with addlw 0xFD, >everything is working! I though the assembler was translating a sublw >into the right addlw?! Is it the same opcode? Dmitry answered your question. {Quote hidden}>Another BIG problem: > > I am reading a byte 0xAD in EEPROM, with: > >EEREAD bsf STATUS,RP0 > bsf EECON1,RD > bcf STATUS,RP0 > movf EEDATA,w > return > > >In my main program I am doing the following code: > > call EEREAD > btfsc w,2 > goto OK > .... >OK "Send to LCD that I have been here" The problem is, you aren't "btfsc w,2" - you are actually executing: btfsc INDF, 2 "w" is evaluated to Zero in MPASM and Register Zero is actually "INDF" (the register pointed to by FSR. In this case, you can either use the working code exchange: btfsc w,2 with andlw 4 ; Isolate Bit 2 btfss STATUS, Z But, I would stick with the working example (not only is it easier to understand, but it doesn't change the value in "w"). Good luck, myke PICList Etiquette at: http://www.myke.com/piclist

David BALDWIN <spam_OUTdbTakeThisOuTSDM.BEL.ALCATEL.BE> wrote: > sublw .3 > >and it is not working properly. When I am replacing it with addlw 0xFD, >everything is working! I though the assembler was translating a sublw >into the right addlw?! Is it the same opcode? sublw .3 does: 3 - w addlw h'fd' does: h'fd' + w = - 3 + w = w - 3 BTW this is a very handy trick to reverse the subtraction order. > > call EEREAD > btfsc w,2 <- Illegal. Can't test bits in w. > goto OK This is actually testing the register pointed to by the FSR register > call EEREAD > btfsc EEREAD,2 <- ?? EEREAD is a label in your program. > goto OK The register actually being tested depends on the address of EEREAD. -- Bob Fehrenbach Wauwatosa, WI .....bfehrenbKILLspam@spam@execpc.com

On Thu, 20 Nov 1997 12:28:25 +0100 David BALDWIN <dbKILLspamSDM.BEL.ALCATEL.BE> writes: > I am back because I need your help. I have an ASM file that >contains: > > sublw .3 > >and it is not working properly. When I am replacing it with addlw >0xFD, >everything is working! I though the assembler was translating a sublw >into the right addlw?! Is it the same opcode? No they are not equivalent. sublw computes W = L - W addlw computes W = L + W They have different opcodes, and different uses. sublw negates W in the process, addlw doesn't. If you use addlw with a negative literal (constant) to effect a subtraction, the result is W - L. > I am reading a byte 0xAD in EEPROM, with: > >EEREAD bsf STATUS,RP0 > bsf EECON1,RD > bcf STATUS,RP0 > movf EEDATA,w > return > Before using this routine, you have to store the EEPROM address of the byte to be read in the EEADR special register. I don't think EEADR is set to any particular known value after a reset. There are only 64 bytes of EEPROM, so EEADR must be set within 0x00 to 0x3F. Attempting to use illegal EEPROM addresses will read 0 (and increase the power consumption somewhat, according to the F84 data). > >In my main program I am doing the following code: > > call EEREAD > btfsc w,2 > goto OK > .... >OK "Send to LCD that I have been here" Except on the PIC17CXX, the btfsc instruction can't work on W. (w and f are predefined to 0 and 1 to use as indications for the instructions that accept either destination, thus this doens;t generate an error. I don't like this very much, I would rather have the assembler parse these instructions looking for either 0,1, or a letter explicitly). Anyway to test a bit in W, you can do a logical AND instruction to isolate the bit, then test the Z flag. But this zeros the other bits in W. Another way is to store the value to RAM, then use a btfs instruction on the bit. If EEADR is beyond 0x3F, then the chip will read zero, and the skip will always skip. > >The problem is that I never go to OK!!! BUT when doing the following: > > call EEREAD > btfsc EEREAD,2 > goto OK > .... This, though technically legal, is programming gibberish. The assembler defines EEREAD as the address of your EEREAD routine in ROM. Trying to use it as an address in RAM will have unpredictable results.

Hi All! m> I have an ASM file that contains: m> m> sublw .3 m> m> and it is not working properly. What do you want ? W-3 ? It's wrong! sublw .3 means W=3-W m> When I am replacing it with addlw 0xFD, everything is working! Of course! 0xFD = .-3, and addlw 0xFD == W-3 m> Another BIG problem: m> m> I am reading a byte 0xAD in EEPROM, with: m> m> EEREAD bsf STATUS,RP0 m> bsf EECON1,RD m> bcf STATUS,RP0 m> movf EEDATA,w m> return m> m> m> In my main program I am doing the following code: m> m> call EEREAD m> btfsc w,2 m> goto OK m> .... m> The problem is that I never go to OK!!! BUT when doing the m> following: m> m> call EEREAD m> btfsc EEREAD,2 m> goto OK m> .... m> OK "Send to LCD that I have been here" m> m> Everithing is working! I really don't understand m> what's happening! Please ... help me. It's very simple :-) When you write "btfss W,2" it's the same, as "btfsc 0,2" - you test the 2nd bit of register, which address=0 - it is INDF, so you test the 2nd bit of register, which address is in FSR. Alex Torres, .....altorKILLspam.....cook.kharkov.ua Kharkov,Ukraine --- GoldED 2.50.A0531+

Hello all, I have found the following piece of code which is included in a delay routine (delay X cycles (11-256) by Regulus Berdin ) : addlw -(.10+1) addlw -4 can i replace it with sublw .11 sublw .4 cause as written literally the compiler did no accept it ! grtz Simon __________________________________________________ Do You Yahoo!? Everything you'll ever need on one web page from News and Sport to Email and Music Charts http://uk.my.yahoo.com -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email EraseMElistservspam_OUTTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

Simon-Thijs de Feber <PICLISTspam_OUTmitvma.mit.edu> wrote: > addlw -(.10+1) > addlw -4 > > can i replace it with > > sublw .11 > sublw .4 Simon: No, you can't do that. "ADDLW -11" subtracts 11 from W; "SUBLW 11" subtracts W from 11. Instead, you can replace it with: addlw .256-(.10+1) ; or addlw 245 addlw .256-.4 ; or addlw 252 -Andy === Andrew Warren -- @spam@aiwKILLspamcypress.com === Principal Design Engineer === Cypress Semiconductor Corporation === === Opinions expressed above do not === necessarily represent those of === Cypress Semiconductor Corporation -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email KILLspamlistservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

Hello, OK i understand. But somehow CC5x does not accept the following inline assembly : addlw -(.10+1) This it accepts : addlw .256 - 11 Why it did not accept the firts line of assembly. grtz Simon __________________________________________________ Do You Yahoo!? Everything you'll ever need on one web page from News and Sport to Email and Music Charts http://uk.my.yahoo.com -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email RemoveMElistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

I must admit ... I've never tried that, but I ran your problem through CC5X, and found two distingt problems. Minus and parentheses. This is not accepted: addlw -11 This is accepted: addlw 0-11 This is not accepted: addlw (-11) This is not accepted: addlw (0-11) It won't take parentheses at all, and it looks like it won't evaluate immediate negative numbers. On the other hand, CC5X will generate the same code in assembler if you do this in C: W+=-11; Dag S STdF> Hello, STdF> OK i understand. STdF> But somehow CC5x does not accept the following inline STdF> assembly : STdF> addlw -(.10+1) STdF> This it accepts : STdF> addlw .256 - 11 STdF> Why it did not accept the firts line of assembly. STdF> grtz STdF> Simon STdF> __________________________________________________ STdF> Do You Yahoo!? STdF> Everything you'll ever need on one web page STdF> from News and Sport to Email and Music Charts STdF> http://uk.my.yahoo.com STdF> -- STdF> http://www.piclist.com#nomail Going offline? Don't AutoReply us! STdF> email spamBeGonelistservspamBeGonemitvma.mit.edu with SET PICList DIGEST in the body -- http://www.piclist.com hint: To leave the PICList TakeThisOuTpiclist-unsubscribe-requestEraseMEspam_OUTmitvma.mit.edu

Burned!!! SUBLW does NOT SUBtract Literal from W! (It subtracts W from Literal) WHY did they reverse the order of the operands in the Mnemonic? * | __O Thomas C. Sefranek RemoveMEtcsTakeThisOuTcmcorp.com |_-\<,_ Amateur Radio Operator: WA1RHP (*)/ (*) Bicycle mobile on 145.41, 448.625 MHz ARRL Instructor, Technical Specialist, VE Contact. hamradio.cmcorp.com/inventory/Inventory.html http://www.harvardrepeater.org -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listservEraseME.....mitvma.mit.edu with SET PICList DIGEST in the body

Every year or so someone is burned by it. There is an obscure reason, but it escapes me at the moment - hope it didn't kill too much of your time! -Adam Thomas C. Sefranek wrote: {Quote hidden}>Burned!!! > >SUBLW does NOT SUBtract Literal from W! >(It subtracts W from Literal) > >WHY did they reverse the order of the operands in the Mnemonic? > > > * > | __O Thomas C. Sefranek EraseMEtcscmcorp.com > |_-\<,_ Amateur Radio Operator: WA1RHP > (*)/ (*) Bicycle mobile on 145.41, 448.625 MHz > >ARRL Instructor, Technical Specialist, VE Contact. >hamradio.cmcorp.com/inventory/Inventory.html >http://www.harvardrepeater.org > >-- >http://www.piclist.com#nomail Going offline? Don't AutoReply us! >email RemoveMElistservEraseMEEraseMEmitvma.mit.edu with SET PICList DIGEST in the body > > > > > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email RemoveMElistservspam_OUTKILLspammitvma.mit.edu with SET PICList DIGEST in the body

Its not really reversed ... SUBLW ... L - W = result >>> EraseMEadampicspamspamBeGoneUBASICS.COM 05/15/02 07:17PM >>> Every year or so someone is burned by it. There is an obscure reason, but it escapes me at the moment - hope it didn't kill too much of your time! -Adam Thomas C. Sefranek wrote: >SUBLW does NOT SUBtract Literal from W! >(It subtracts W from Literal) >WHY did they reverse the order of the operands in the Mnemonic? > | __O Thomas C. Sefranek RemoveMEtcsKILLspamcmcorp.com -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestSTOPspamspam_OUTmitvma.mit.edu

----- Original Message ----- From: "Douglas Wood" <EraseMEdbwoodEraseMEKC.RR.COM> To: <@spam@PICLIST@spam@spam_OUTMITVMA.MIT.EDU> Sent: Thursday, May 16, 2002 9:31 AM Subject: Re: [PIC]: SUBLW > Most micros use the "register minus literal" method... But why waste the opcode space when you can just use "register plus -(literal) instead". Actually, I have found sublw to be very useful on several occasions. Bob Ammerman RAm Systems -- http://www.piclist.com hint: To leave the PICList spamBeGonepiclist-unsubscribe-requestKILLspammitvma.mit.edu

At 10:23 AM 5/16/02 -0400, Bob Ammerman wrote: >But why waste the opcode space when you can just use "register >plus -(literal) instead". Note that ADDLW and SUBLW don't exist in the 12 bit core parts. I have to be careful when porting existing code written for the 14 bit parts over to the 12 bit family. dwayne Dwayne Reid <.....dwaynerspam_OUTplanet.eon.net> Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 18 years of Engineering Innovation (1984 - 2002) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. -- http://www.piclist.com hint: To leave the PICList TakeThisOuTpiclist-unsubscribe-request.....TakeThisOuTmitvma.mit.edu