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Hi all, I have a couple of questions concerning Microchip's code for "adding music to your next project". I attached the code but you can see their article with a functional description at: http://www.microchip.com/1000/edit/proceed/archive/9_179/index.htm 1) Their code includes the instruction 'addwf PCL,F'. What does the 'F' designate as I cannot find this in any of the instruction descriptions for the 16F84 or 84A? Is that 'F' supposed to be the destination bit for the result of the add and if so, where do we want it to go? (Does the compiler look at the 'F' and interpret that as putting the result in the specified file register?) 2) When they say the code is interrupt driven, does that mean that I have to provide an input to generate an interrupt to begin the play of music? When I compile the code and program the chip and connect RA0 as they have described, nothing happens. I simulated the code in MPLAB and found that after the Main routine is called from org 0x000, Initialize is called where a movlw 0x00 is performed before calling Notes where the addwf PCL,F occurrs with the result being PCL set to 0x00 (which I thought was strange since adding 0 to any number should result in the original number and not 0). This takes the program back to the beginning and it starts this all over again in a loop. Any comments or corrections would be appreciated as I am relatively new to PIC programming (about two months experience) and I am still trying to learn all I can. Thanks for your time, Stephen D. Barnes | |||
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Microchip Music example
Started by ●July 14, 2003
Reply by ●July 14, 20032003-07-14
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1) Yes, the 'F' is the destination of the result - either W or F
depending on the requirement 2) The code is interrupt driven in that TMR0 is being used to generate the timing by causing an interrupt. Remember this code is set for 4 MHz. You are correct, the code at Check4 does not work. They have set PCLATH to 0x00 when, in fact, the table is at 0x100. They have taken the easy way out on Table Lookup by limiting the tables to 255 elements and starting on a 256 byte boundary (don't know if you were following along on the lengthy discussion re: Table Lookup we had last week). In any event, when PCLATH is being loaded before the call to Notes (and Durations) it should be set to HIGH(Notes) or HIGH (Durations) before the call. It isn't even set for Durations so that lookup will NEVER work. Worse yet, they don't save PCLATH when the interrupt code is entered. In fact, they don't save FSR either. The thing is, interrupt code MUST leave the machine in the same condition on exit that it had on entrance. In this case it is not a serious problem because the Main code does nothing so it doesn't care what the interrupt routine does. Also, if PCLATH is set correctly during the interrupt routine and then restored properly, the goto $ in Main might actually work. If I get a chance I will try to get the thing to work - probably on a 20 MHz 16F877 and I'll post the results. --- In , "Stephen D. Barnes" <stephendbarnes@h...> wrote: > Hi all, > I have a couple of questions concerning Microchip's code for "adding music > to your > next project". I attached the code but you can see their article with a > functional description at: > http://www.microchip.com/1000/edit/proceed/archive/9_179/index.htm > > 1) Their code includes the instruction 'addwf PCL,F'. What does the 'F' > designate as I cannot find this in any of the instruction descriptions > for the 16F84 or 84A? Is that 'F' supposed to be the destination bit for > the result of the add and if so, where do we want it to go? (Does the > compiler look at the 'F' and interpret that as putting the result in the > specified file register?) > > 2) When they say the code is interrupt driven, does that mean that I have to > provide an input to generate an interrupt to begin the play of music? > > When I compile the code and program the chip and connect RA0 as they have > described, nothing happens. I simulated the code in MPLAB and found that > after the Main routine is called from org 0x000, Initialize is called where > a movlw 0x00 is performed before calling Notes where the addwf PCL,F occurrs > with the result being PCL set to 0x00 (which I thought was strange since > adding 0 to any number should result in the original number and not 0). This > takes the program back to the beginning and it starts this all over again in > a loop. > > Any comments or corrections would be appreciated as I am relatively new to > PIC programming (about two months experience) and I am still trying to learn > all I can. > > Thanks for your time, > Stephen D. Barnes |
Reply by ●July 14, 20032003-07-14
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Thanks for the reply!
I'm not up to speed on setting PCL and register save
and restore for interrupt routines yet. I could learn from reading some good,
well commented code (and this example would also be useful to me). If you get
around to it I would appreciate seeing the results you achieve.
Regards,
Stephen D. Barnes
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Reply by ●July 14, 20032003-07-14
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I'll post it because I have some interest in the result - perhaps a little song from one of my robot toys. I have started working over the code but I have to deal with the 4 MHz vs 20 MHz issue. I'm starting to think about that now - I really want it to be a configuration thing, not some complex process to select between the two. Or I have to put a 4 MHz crystal in one of my prototype boards - that would be acceptable for proof-of-concept. More to follow... --- In , "Stephen D. Barnes" <stephendbarnes@h...> wrote: > Thanks for the reply! > I'm not up to speed on setting PCL and register save and restore for interrupt routines yet. I could learn from reading some good, well commented code (and this example would also be useful to me). If you get around to it I would appreciate seeing the results you achieve. > > Regards, > Stephen D. Barnes > ----- Original Message ----- > From: rtstofer > To: > Sent: Monday, July 14, 2003 8:28 AM > Subject: [piclist] Re: Microchip Music example > 1) Yes, the 'F' is the destination of the result - either W or F > depending on the requirement > > 2) The code is interrupt driven in that TMR0 is being used to > generate the timing by causing an interrupt. Remember this code is > set for 4 MHz. > > You are correct, the code at Check4 does not work. They have set > PCLATH to 0x00 when, in fact, the table is at 0x100. They have taken > the easy way out on Table Lookup by limiting the tables to 255 > elements and starting on a 256 byte boundary (don't know if you were > following along on the lengthy discussion re: Table Lookup we had > last week). In any event, when PCLATH is being loaded before the > call to Notes (and Durations) it should be set to HIGH(Notes) or HIGH > (Durations) before the call. It isn't even set for Durations so that > lookup will NEVER work. > > Worse yet, they don't save PCLATH when the interrupt code is > entered. In fact, they don't save FSR either. The thing is, > interrupt code MUST leave the machine in the same condition on exit > that it had on entrance. In this case it is not a serious problem > because the Main code does nothing so it doesn't care what the > interrupt routine does. > > Also, if PCLATH is set correctly during the interrupt routine and > then restored properly, the goto $ in Main might actually work. > > If I get a chance I will try to get the thing to work - probably on a > 20 MHz 16F877 and I'll post the results. > > --- In , "Stephen D. Barnes" > <stephendbarnes@h...> wrote: > > Hi all, > > I have a couple of questions concerning Microchip's code > for "adding music > > to your > > next project". I attached the code but you can see their article > with a > > functional description at: > > http://www.microchip.com/1000/edit/proceed/archive/9_179/index.htm > > > > 1) Their code includes the instruction 'addwf PCL,F'. What does > the 'F' > > designate as I cannot find this in any of the instruction > descriptions > > for the 16F84 or 84A? Is that 'F' supposed to be the destination > bit for > > the result of the add and if so, where do we want it to go? (Does > the > > compiler look at the 'F' and interpret that as putting the result > in the > > specified file register?) > > > > 2) When they say the code is interrupt driven, does that mean that > I have to > > provide an input to generate an interrupt to begin the play of > music? > > > > When I compile the code and program the chip and connect RA0 as > they have > > described, nothing happens. I simulated the code in MPLAB and found > that > > after the Main routine is called from org 0x000, Initialize is > called where > > a movlw 0x00 is performed before calling Notes where the addwf > PCL,F occurrs > > with the result being PCL set to 0x00 (which I thought was strange > since > > adding 0 to any number should result in the original number and not > 0). This > > takes the program back to the beginning and it starts this all over > again in > > a loop. > > > > Any comments or corrections would be appreciated as I am relatively > new to > > PIC programming (about two months experience) and I am still trying > to learn > > all I can. > > > > Thanks for your time, > > Stephen D. Barnes > > > to unsubscribe, go to http://www.yahoogroups.com and follow the instructions > > Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. |
Reply by ●July 14, 20032003-07-14
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Fantastic! I'm working with 16F84A's at 10MHz and
16F628's at 4 and 10MHz so the 4MHz version would be great (changing
prescale values isn't that big a deal though to get the right pitch). This
code looked promising to me because it appeared to be more elegant than my
kludged together tone generation routines!
Regards,
Stephen D. Barnes
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Reply by ●July 14, 20032003-07-14
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Stephen,
The attached file is for the 16F877 at
4MHz. You should be able to change the chip description in the first 3
lines to 16F628 and it should work. I don't know about the
16F84.
Enjoy!
Richard
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Reply by ●July 15, 20032003-07-15
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Thanks.
I must be overlooking something that is staring me right in
the eyes! I changed the info in the file for the F628 and loaded it up......got
one click only. Simulated the code....goes to Main, calls Initialize which calls
Notes(which returns to Initialize) where Initialize executes the next five
instructions then returns to Main then falls into Loop where it remains.
I'm lost.
What am I doing wrong?
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Reply by ●July 15, 20032003-07-15
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All of the work is performed in the InterruptEntry code. I don't know how you can simulate this, the code is entered when Timer 0 overflows. You can see in the code with TMR0 is being loaded with various values. At every clock / 4 / prescaler, the count in TMR0 is incremented. When it overflows from 255 to 0 an interrupt T0IF is generated. But you are having difficulty with the F628 so let me take a look - I have a prototype board that is being used for something else but I can knock it down pretty quick. --- In , "Stephen D. Barnes" <stephendbarnes@h...> wrote: > Thanks. > I must be overlooking something that is staring me right in the eyes! I changed the info in the file for the F628 and loaded it up......got one click only. Simulated the code....goes to Main, calls Initialize which calls Notes(which returns to Initialize) where Initialize executes the next five instructions then returns to Main then falls into Loop where it remains. I'm lost. > What am I doing wrong? > > ----- Original Message ----- > From: R.Stofer > To: piclist@g... > Sent: Monday, July 14, 2003 9:41 PM > Subject: [piclist] Re: Microchip Music Example > Stephen, > > The attached file is for the 16F877 at 4MHz. You should be able to change the chip description in the first 3 lines to 16F628 and it should work. I don't know about the 16F84. > > Enjoy! > Richard > > to unsubscribe, go to http://www.yahoogroups.com and follow the instructions > > Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. |
Reply by ●July 15, 20032003-07-15
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Stephen,
Attached is code for the 16F628 using the
internal 4MHz oscillator. You can change the __CONFIG for your
application.
I also initialized CMCON in
'Initialize' but I can not figure you why I have to toggle RA1 in the
Loop code to make this thing work. I also defined PORTA as having 8 bits
with RA0 and RA1 as output.
I usually put toggle code in various spots like
Loop and the beginning of InterruptEntry so I can check things with a
scope. That's how I discovered the code required at
Loop.
It's late, I'll get back to it
tomorrow. In the meantime, the code works for me!
Richard
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Reply by ●July 15, 20032003-07-15
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Hello, Can anybody help me? I need a LCD and Keypad Interface code for pic16F876. The LCD interface code i have. I dont know like i put Keypad interface in my code. Thank you Marcela _______________________________________________________________________ Yahoo! Mail O melhor e-mail gratuito da internet: 6MB de espa, antivus, acesso POP3, filtro contra spam. http://br.mail.yahoo.com/ |
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