Post by thread:[PIC]: USART overrun problem

Hi Martin, You have to use the interrupt routine to clean the buffer. Can you post your code ? Regards, Nicolas > Hi all, > i4m trying to comunicate a PC with a PIC16f874(clock 4 MHZ) , using the USART asynchronous mode at 9600 bps. The length of each message is 8 >bytes (8bits,Non Parity,1Stop bit). This PIC has a FIFO buffer(Register RCREG) of two bytes, so the idea is to clean the buffer before the third byte >reach the buffer, i4ve been triying to improve the code in the PIC to clean the buffer as fast as possible, but i 4m still having this problem. Is there any good >code to avoid it? Can it be done adding hardware? Thanks a lot -- http://www.piclist.com hint: To leave the PICList spam_OUTpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu

> Hi all, > i4m trying to comunicate a PC with a PIC16f874(clock 4 MHZ) > using the USART asynchronous mode at 9600 bps. The length of > each message is 8 bytes (8bits,Non Parity,1Stop bit). This PIC has > a FIFO buffer(Register RCREG) of two bytes, > the buffer before the third byte reach the buffer, And you should read the incomming byte as fast as possible after the flag is set (can't remeber the name, but you'll find it...) There is not need to wait for two bytes in the RCREG FIFO. Why wait ? You have to read each byte anyway, better do it at once. I do not think the "FIFO" was ment to be "used" in that way. > in the PIC to clean the buffer as fast as possible, Exactly *how* do you know when to read the incomming bytes(s) ? > but i 4m still having this problem. > Is there any good code to avoid it? Any code but yours, probably :-) :-) > Can it be done adding hardware? That should definitly not be needed at 9600 baud ! Just read each byte as they are received. Regards, Jan-Erik. -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestKILLspam@spam@mitvma.mit.edu

MeLabs has an example for the 16F877 @4MHz. Interrupt-driven, 32 byte buffer, 9600 bps hardware serial using assembly language interrupt handler. http://www.microengineeringlabs.com/resources/samples/x1/pbp/serbufAx.bas Portions are in BASIC, but the USART int/buffer code is all assembly. Regards, -Bruce techKILLspamrentron.com http://www.rentron.com > Hi all, > i´m trying to comunicate a PC with a PIC16f874(clock 4 MHZ) , using the USART asynchronous mode at 9600 bps. The length of each message is 8 bytes (8bits,Non Parity,1Stop bit). This PIC has a FIFO buffer(Register RCREG) of two bytes, so the idea is to clean the buffer before the third byte reach the buffer, i´ve been triying to improve the code in the PIC to clean the buffer as fast as possible, but i ´m still having this problem. Is there any good code to avoid it? Can it be done adding hardware? Thanks a lot > __________________________________________________ -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestKILLspam.....mitvma.mit.edu

And don't forget Olin Lathrop's perfectly working all-ASM environment. His USART macros with FIFO (for both send and receive!) worked out-of-the-box first time for me. Jan-Erik. PS. Has anyone heard from Olin lately ? Bruce wrote : > MeLabs has an example for the 16F877 @4MHz. > > Interrupt-driven, 32 byte buffer, 9600 bps hardware serial > using assembly language interrupt handler. > > www.microengineeringlabs.com/resources/samples/x1/pbp/s > erbufAx.bas > > Portions are in BASIC, but the USART int/buffer code is all assembly. -- http://www.piclist.com hint: To leave the PICList EraseMEpiclist-unsubscribe-requestspam_OUTTakeThisOuTmitvma.mit.edu

> Greetings Jan-Erik. > > Is this code available somewhere? I would like to check it out. > > Thank you. > Fred > Start at http://www.embedinc.com/pic/ and drill down from there. Note, the actual code (even if not to hard to use) could be a bit frustrating to "read" if you're not up-to-speed on Olin's special development environment. A very good environent anyway, if you ask me... And yes, nearly forgot, *I* have made a PDF version of Olins web based docs. You can find that on http://www.st-anna-data.se/ under the "PIC page" menu selection. I checked about a month ago, and there didn't seems to be any (major) changes in Olins pages. Jan-Erik. -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestspam_OUTmitvma.mit.edu

How much time is there between each 8 byte packet? Could you simply buffer each byte as it arrives in your ISR and then raise a flag to be dealt with in your main routine once all 8 bytes have arrived? Any PIC should be able to deal with data coming in at 9600 bps...right now, I have a PIC running at 3.68 MHz which grabs the byte and stuffs it out via SPI, and it's receiving data at 115.2 kbps, AND not using interrupts, so it has to be possible. Mike H. >Hi all, >i4m trying to comunicate a PC with a PIC16f874(clock 4 MHZ) , using the >USART asynchronous mode at 9600 bps. The length of each message is 8 bytes >(8bits,Non Parity,1Stop bit). This PIC has a FIFO buffer(Register RCREG) of >two bytes, so the idea is to clean the buffer before the third byte reach >the buffer, i4ve been triying to improve the code in the PIC to clean the >buffer as fast as possible, but i 4m still having this problem. Is there >any good code to avoid it? Can it be done adding hardware? Thanks a lot _________________________________________________________________ MSN 9 Dial-up Internet Access fights spam and pop-ups now 3 months FREE! http://join.msn.click-url.com/go/onm00200361ave/direct/01/ -- http://www.piclist.com hint: To leave the PICList @spam@piclist-unsubscribe-requestKILLspammitvma.mit.edu

Have a look at Tom's code 'picuart.asm' for an axample of catching all those errors; ; PICUART.ASM ; Microchip MPASM format ; ; version 1.04.1 ; Last modified July 24, 2000 ; ; A Program and Document ; designed to help others learn how to use the ; built-in UART features of ; the PIC microcontroller family. ; ;The program has been verified on MANY PIC microcontrollers. ;No one has reported any PIC with built-in UART which the ;program does not work with so far. ; ; Written by ; Fr. Thomas McGahee ; KILLspamtom_mcgaheeKILLspamsigmais.com ; primary web site http://redrival.com/mcgahee ; secondary website http://mcgahee.freeservers.com .............. {Quote hidden}>>Hi all, >>i4m trying to comunicate a PC with a PIC16f874(clock 4 MHZ) , using the >>USART asynchronous mode at 9600 bps. The length of each message is 8 bytes >>(8bits,Non Parity,1Stop bit). This PIC has a FIFO buffer(Register RCREG) of >>two bytes, so the idea is to clean the buffer before the third byte reach >>the buffer, i4ve been triying to improve the code in the PIC to clean the >>buffer as fast as possible, but i 4m still having this problem. Is there >>any good code to avoid it? Can it be done adding hardware? Thanks a lot > >_________________________________________________________________ >MSN 9 Dial-up Internet Access fights spam and pop-ups now 3 months FREE! >http://join.msn.click-url.com/go/onm00200361ave/direct/01/ > >-- >http://www.piclist.com hint: To leave the PICList >RemoveMEpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu Regards Roland Jollivet -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Those links appear dead ('least here) try http://www.pic101.com/mcgahee/index.html Dave At 05:33 AM 6/10/04, you wrote: {Quote hidden}>Have a look at Tom's code 'picuart.asm' for an axample of catching all >those errors; > > >; PICUART.ASM >; Microchip MPASM format >; >; version 1.04.1 >; Last modified July 24, 2000 >; >; A Program and Document >; designed to help others learn how to use the >; built-in UART features of >; the PIC microcontroller family. >; >;The program has been verified on MANY PIC microcontrollers. >;No one has reported any PIC with built-in UART which the >;program does not work with so far. >; >; Written by >; Fr. Thomas McGahee >; spamBeGonetom_mcgaheespamBeGonesigmais.com >; primary web site http://redrival.com/mcgahee >; secondary website http://mcgahee.freeservers.com -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

FYI, one of Tom's authorized archived websites is at: http://www.pic101.com/mcgahee Rick Roland wrote: {Quote hidden}> Have a look at Tom's code 'picuart.asm' for an axample of catching all > those errors; > > ; PICUART.ASM > ; Microchip MPASM format > ; > ; version 1.04.1 > ; Last modified July 24, 2000 > ; > ; A Program and Document > ; designed to help others learn how to use the > ; built-in UART features of > ; the PIC microcontroller family. > ; > ;The program has been verified on MANY PIC microcontrollers. > ;No one has reported any PIC with built-in UART which the > ;program does not work with so far. > ; > ; Written by > ; Fr. Thomas McGahee > ; TakeThisOuTtom_mcgaheeEraseMEspam_OUTsigmais.com > ; primary web site http://redrival.com/mcgahee > ; secondary website http://mcgahee.freeservers.com > > .............. > > >>Hi all, > >>i4m trying to comunicate a PC with a PIC16f874(clock 4 MHZ) , using the > >>USART asynchronous mode at 9600 bps. The length of each message is 8 bytes > >>(8bits,Non Parity,1Stop bit). This PIC has a FIFO buffer(Register RCREG) of > >>two bytes, so the idea is to clean the buffer before the third byte reach > >>the buffer, i4ve been triying to improve the code in the PIC to clean the > >>buffer as fast as possible, but i 4m still having this problem. Is there > >>any good code to avoid it? Can it be done adding hardware? Thanks a lot > > > >_________ -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Another archive is here: http://ubasics.com/mcgahee/ -Adam Roland wrote: {Quote hidden}>Have a look at Tom's code 'picuart.asm' for an axample of catching all >those errors; > > >; PICUART.ASM >; Microchip MPASM format >; >; version 1.04.1 >; Last modified July 24, 2000 >; >; A Program and Document >; designed to help others learn how to use the >; built-in UART features of >; the PIC microcontroller family. >; >;The program has been verified on MANY PIC microcontrollers. >;No one has reported any PIC with built-in UART which the >;program does not work with so far. >; >; Written by >; Fr. Thomas McGahee >; RemoveMEtom_mcgaheeTakeThisOuTsigmais.com >; primary web site http://redrival.com/mcgahee >; secondary website http://mcgahee.freeservers.com > >.............. > > > >>>Hi all, >>>i4m trying to comunicate a PC with a PIC16f874(clock 4 MHZ) , using the >>>USART asynchronous mode at 9600 bps. The length of each message is 8 bytes >>>(8bits,Non Parity,1Stop bit). This PIC has a FIFO buffer(Register RCREG) of >>>two bytes, so the idea is to clean the buffer before the third byte reach >>>the buffer, i4ve been triying to improve the code in the PIC to clean the >>>buffer as fast as possible, but i 4m still having this problem. Is there >>>any good code to avoid it? Can it be done adding hardware? Thanks a lot >>> >>> >>_________________________________________________________________ >>MSN 9 Dial-up Internet Access fights spam and pop-ups now 3 months FREE! >>join.msn.click-url.com/go/onm00200361ave/direct/01/ >> >>-- >>http://www.piclist.com hint: To leave the PICList >>piclist-unsubscribe-requestEraseME.....mitvma.mit.edu> >> >> > > >Regards >Roland Jollivet > >-- >http://www.piclist.com hint: PICList Posts must start with ONE topic: >[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > > > > -- 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