Post by thread:[PIC]: Question

Hi All, I have a question: 1.Why doesn't this work? list p=16f876 include "P16f876.inc" ;............................... tmp equ 0x21 ;............................... org 0x00 goto start ;............................... start movlw 0x1 movwf tmp nop if tmp = = 1 call sub1 else call sub2 endif nop ;............................... sub1 nop return ;.............................. sub2 nop return end -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Sounds like your confused between assembler "opcodes" and assembler "directives". You write your PROGRAM with opcodes. You tell the assember what to do with directives. What you are telling the compiler is >IF< tmp was equal to "1" then use the line "call sub1" in your program. However, you set tmp to 0x21 so the line "call sub2" will be in your program instead. This is about what the program will look like AFTER if is compiled: list p=16f876 include "P16f876.inc" ;............................... tmp equ 0x21 ;............................... org 0x00 goto start ;............................... start movlw 0x1 movwf tmp nop *** call sub2 *** nop ;............................... sub1 nop return ;.............................. sub2 nop return end What you want to do is something like this movf tmp,f ;Copy tmp into itself to set the ZERO flag if tmp = 0 btfss STATUS,Z ;Look at the ZERO flag to see if it is set goto Jmp1 ;You don't want a call statement here unless you ALWAYS want ;the next line executed after you return. This line executes if not ZERO goto Jmp2 ;This line executes if ZERO Jmp1 call Sub1 ;Do your subroutine goto Start ;Loop back again after you return Jmp2 call Sub2 ;Do your subroutine goto Start ;Loop back again after you return basam wrote: {Quote hidden}> Hi All, > I have a question: > 1.Why doesn't this work? > > list p=16f876 > include "P16f876.inc" > ;............................... > tmp equ 0x21 > ;............................... > org 0x00 > goto start > ;............................... > start > movlw 0x1 > movwf tmp > nop > if tmp = = 1 > call sub1 > else > call sub2 > endif > nop > ;............................... > sub1 > nop > return > ;.............................. > sub2 > nop > return > end > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

----- Original Message ----- From: "basam" <.....basamKILLspam@spam@EMO.SEAS.SK> To: <PICLISTKILLspamMITVMA.MIT.EDU> Sent: Saturday, June 02, 2001 9:52 PM Subject: [PIC]: Question > Hi All, > I have a question: > 1.Why doesn't this work? Because you are confusing assembly time operations with runtime operations. IF is an instruction to the assembler, very similar to #if in "C" that controls what code is actually ASSEMBLED. I have taken the liberty to modify your code to actually work. {Quote hidden}> > list p=16f876 > include "P16f876.inc" > ;............................... > tmp equ 0x21 > ;............................... > org 0x00 > goto start > ;............................... > start > movlw 0x1 > movwf tmp > nop > if tmp = = 1 > call sub1 > else > call sub2 > endif movf tmp,W ; Get saved value of tmp xorlw 1 ; compare it to 1 skpz ; skip if they are equal goto unequal call sub1 goto merge unequal: call sub2 merge: {Quote hidden}> nop > ;............................... > sub1 > nop > return > ;.............................. > sub2 > nop > return > end > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> 1.Why doesn't this work? I'm sure it does work exactly as you wrote it. If that isn't what you intended, then I can't say because you never said what you wanted it to do. <soapbox> ***** COMMENT YOUR CODE, *&#$&@ ! ***** </soapbox> {Quote hidden}> list p=16f876 > include "P16f876.inc" > ;............................... > tmp equ 0x21 > ;............................... > org 0x00 > goto start > ;............................... > start > movlw 0x1 > movwf tmp > nop > if tmp = = 1 Note that this is always false since TMP = 21h. > call sub1 > else > call sub2 > endif > nop Note that this will fall thru to SUB1, which will do a RETURN and cause a stack underflow. {Quote hidden}> ;............................... > sub1 > nop > return > ;.............................. > sub2 > nop > return > end ******************************************************************** Olin Lathrop, embedded systems consultant in Littleton Massachusetts (978) 742-9014, .....olinKILLspam.....embedinc.com, http://www.embedinc.com -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Olin Lathrop wrote: {Quote hidden}> > 1.Why doesn't this work? > > I'm sure it does work exactly as you wrote it. If that isn't what you > intended, then I can't say because you never said what you wanted it to do. > > <soapbox> > ***** COMMENT YOUR CODE, *&#$&@ ! ***** > </soapbox> > > > list p=16f876 > > include "P16f876.inc" > > ;............................... > > tmp equ 0x21 > > ;............................... > > org 0x00 > > goto start > > ;............................... > > start > > movlw 0x1 > > movwf tmp > > nop > > if tmp = = 1 > > Note that this is always false since TMP = 21h. > > > call sub1 > > else > > call sub2 > > endif > > nop > > Note that this will fall thru to SUB1, which will do a RETURN and cause a > stack underflow. > > > ;............................... > > sub1 > > nop > > return > > ;.............................. > > sub2 > > nop > > return > > end > > ******************************************************************** > Olin Lathrop, embedded systems consultant in Littleton Massachusetts > (978) 742-9014, EraseMEolinspam_OUTTakeThisOuTembedinc.com, http://www.embedinc.com > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. I have no real problem, I only wanted to test IF..ELSE..ENDIF condition, but I think I mixed everything together.(It looks like I have a little big problems with assembling :-) ). I need to initialise tmp, You say ,that if I will do this with EQU, then the value will be 21h, but I thought that 21h is its adress. I need to give some adress where to put tmp, not value. I am going to study MPASM-HELP. Thanx to Everybody Milan -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Hi Milan, The tutorial here might be of some value. http://pc-tek.hypermart.net/pic.html Heinz At 12:49 AM +0200 6/4/01, basam wrote: {Quote hidden}> > >I have no real problem, I only wanted to test IF..ELSE..ENDIF condition, but I >think I mixed everything together.(It looks like I have a little big problems >with assembling :-) ). >I need to initialise tmp, You say ,that if I will do this with EQU, then the >value will be 21h, but I thought that 21h is its adress. >I need to give some adress where to put tmp, not value. >I am going to study MPASM-HELP. > Thanx to Everybody > >Milan > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

You really REALLY R E A L L Y need to understand the difference between "opcodes" and "directives". One is used for the "program", the other is NOT!! If you want to learn programming, then forget the MPASM-HELP (at first) and memorize the small list of what opcodes are available for the processor you are useing. You don't have to memorize exactly what they do but learn whats available. After that then it should be ALOT easier to learn and use the assembly "directives" such as EQU to support the programming. On the same note, tutorials are really good too. To answer your other question. EQU is a "directive", not an "opcode". When you put the line of tmp EQU 0x21 into your code, that was a "directive" to the assembler. It is NOT a line that will be put into your compiled program. If within my "program" I want to put the value of the W register into memory register 0x21, I can do it in either of the following two ways: movwf 0x21 movwf tmp This is because tmp = 0x21. What the assembler (MPASM) will do is make a substitution in your "program". Everywhere that it see the word 'tmp' it will put '0x21' instead. The IF..ELSE..ENDIF "directives" are another set of commands that are sent to the assembler but are NOT part of the "program". Learn your opcodes first. Heinz Czychun wrote: {Quote hidden}> Hi Milan, > > The tutorial here might be of some value. > > http://pc-tek.hypermart.net/pic.html > > Heinz > > At 12:49 AM +0200 6/4/01, basam wrote: > > > > > >I have no real problem, I only wanted to test IF..ELSE..ENDIF condition, but I > >think I mixed everything together.(It looks like I have a little big problems > >with assembling :-) ). > >I need to initialise tmp, You say ,that if I will do this with EQU, then the > >value will be 21h, but I thought that 21h is its adress. > >I need to give some adress where to put tmp, not value. > >I am going to study MPASM-HELP. > > Thanx to Everybody > > > >Milan > > > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listservspam_OUTmitvma.mit.edu with SET PICList DIGEST in the body

> I have no real problem, I only wanted to test IF..ELSE..ENDIF condition, but I > think I mixed everything together.(It looks like I have a little big problems > with assembling :-) ). > I need to initialise tmp, You say ,that if I will do this with EQU, then the > value will be 21h, but I thought that 21h is its adress. > I need to give some adress where to put tmp, not value. You are confusing assembler variables and constants, and the runtime value located at addresses that are referenced by those assemlber variables and constants. First, assembler symbols never stand for the contents of a RAM location, because that can't be determined at assembly time. These symbols can stand for arbitrary number or memory addresses (which are also just numbers). When you say: TMP EQU h'21' you assign the value 21h to the assembler symbol TMP. Nothing more. TMP is NOT a memory location, and TMP absolutely does not refer to the contents of any memory location. However TMP, like any other symbol, can be used as the address of a memory location. For example: MOVWF TMP, W ;fetch the value at TMP But the assembler only knows that TMP = 21h. It doesn't know that you think of that as representing the address of a memory location. You could just as well use it as a normal numeric constant: MOVLW TMP ;init the loop counter MOVWF LOOPCNT > I am going to study MPASM-HELP. A very good idea. However, you might start with a book or something that introduces assembly language programming in general. The Microchip documentation pretty much assumes you already know how assemblers work and teaches you the specifics of MPASM. You are having problems with general concepts that may not be well addressed in the MPASM manual. ******************************************************************** Olin Lathrop, embedded systems consultant in Littleton Massachusetts (978) 742-9014, @spam@olinKILLspamembedinc.com, http://www.embedinc.com -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email KILLspamlistservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

On Fri, Jun 08, 2001 at 11:57:56AM -0700, Kashif Ali wrote: > Hi all, > > I need more then 100 reg but 16f874 has only 96 reg in its first bank and I > don't know how to utilize next bank reg. > > Please give an example of utilizing both bank 0 & 1 in one routine. > > Kashif ali Kashif, You need a copy of the datasheet. It describes exactly how to change banks. It's section 2.2 of the 16F87X datasheet. Page 12. More detail can be found in the 16F family midrange manual in section 6.3.3 on page 6-8. Also in both manuals take a read of the indirect addressing feature using FSR and INDF. They can be utilized for the task also. I know this may seem unfair, but I'm not going to answer your question, and I hope that no one else will answer it either. This is information is that is clearly documented. Frankly you would have saved a ton of time if you had taken the time to look it up yourself. You can't program microcontrollers without the documentation. You also must read it. Get a copy of the documents above from the Microchip website, and take a read of the sections. Then try it. Then come back if necessary and post the relevant code and the results. In this way you will get a clearer understanding of the process instead of simply asking and getting back a code snippet. I will give you one hint: bank switching for general purpose registers is exactly the same process as setting the TRIS registers for the I/O ports for ports D, and E (which are on an 16F874). Did you use ports D or E? If so then how did you change the TRIS registers? It's the same process for general purpose. Good luck, and let us know how it comes out.... BAJ -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Thanks for your reply, But still I have question : Actually I need 64 reg for working and 64 reg for backup purpose. Now the problem is how can I simply backup working reg (bank0) into backup registers (bank 1). Please give me a short example for moving working reginster into backup registers. Kashif ali Byron A Jeff wrote: {Quote hidden}> On Fri, Jun 08, 2001 at 11:57:56AM -0700, Kashif Ali wrote: > > Hi all, > > > > I need more then 100 reg but 16f874 has only 96 reg in its first bank and I > > don't know how to utilize next bank reg. > > > > Please give an example of utilizing both bank 0 & 1 in one routine. > > > > Kashif ali > > Kashif, > > You need a copy of the datasheet. It describes exactly how to change banks. > It's section 2.2 of the 16F87X datasheet. Page 12. More detail can be found > in the 16F family midrange manual in section 6.3.3 on page 6-8. Also > in both manuals take a read of the indirect addressing feature using FSR > and INDF. They can be utilized for the task also. > > I know this may seem unfair, but I'm not going to answer your question, and > I hope that no one else will answer it either. This is information is that > is clearly documented. Frankly you would have saved a ton of time if you had > taken the time to look it up yourself. > > You can't program microcontrollers without the documentation. You also must > read it. Get a copy of the documents above from the Microchip website, and > take a read of the sections. Then try it. Then come back if necessary and post > the relevant code and the results. In this way you will get a clearer > understanding of the process instead of simply asking and getting back a > code snippet. > > I will give you one hint: bank switching for general purpose registers is > exactly the same process as setting the TRIS registers for the I/O ports for > ports D, and E (which are on an 16F874). Did you use ports D or E? If so then > how did you change the TRIS registers? It's the same process for general > purpose. > > Good luck, and let us know how it comes out.... > > BAJ > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

If you use FSR you don't have to set any bits for between bank0 and bank1 (it is explained in the data sheet). So, to copy a register from 0x021 in bank0 to 0x0A1 in bank1: MOVLW 0X021 ;value of register to copy MOVWF FSR ;point to that register MOVF INCF,W ;move and MOVWF TEMP1 ;save contents in a temporary register MOVLW 0X0A1 ;value of register to save in MOVWF FSR ;point to that register MOVF TEMP1,W ;move contents and MOVWF INDF ;save it in that register Loop that for all your other registers. Read the data sheets on using the FSR, it is a very handy function to use. Quentin -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

> Actually I need 64 reg for working and 64 reg for backup purpose. > Now the problem is how can I simply backup working reg (bank0) into backup > registers (bank 1). > > Please give me a short example for moving working reginster into backup registers. I agree with Byron. Your question leaves the impression that you don't want to bother reading the manual and want someone just to solve the problem for you. I'm not going to do that. Come back after you've done the basic homework and have specific questions. HINT: you can index thru memory buffers by using indirect addressing. This is done by use of the INDF and FSR registers. ******************************************************************** Olin Lathrop, embedded systems consultant in Littleton Massachusetts (978) 742-9014, RemoveMEolinTakeThisOuTembedinc.com, http://www.embedinc.com -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Ali, The reset circuit is shown at page138 from DS30292A ( datasheet) R=10k to vcc, 1n4148 cathode to vcc, from common point one 47...100nF capacitor to ground, common point to mclr through 100 ohm resistor. Check also if BODEN is enable and power supply is clean. Vasile On Tue, 12 Jun 2001, Kashif Ali wrote: {Quote hidden}> Hi all, > > I am working on 16f874 newly and facing problem of (MCLR) reset. > Same hardware I am using for 16f84a it worked perfactly but with 16f874 working > randumly. > > Kashif Ali > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics