Post by thread:[PIC]: filling unused program memory

I would like to fill in unused portions of the program memory with a specific value (0x0000), but am unsure how this can be done without tediously inserting the values manually or by using FILL directives throughout the code. Using a FILL directive at the very beginning of code of course will give me overwrite errors when compiled. Any suggestions? -- http://www.piclist.com hint: To leave the PICList spam_OUTpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu

On Tue, 12 Mar 2002 16:55:29 -0600, you wrote: >I would like to fill in unused portions of the program memory with a >specific value (0x0000), why? -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestKILLspam@spam@mitvma.mit.edu

Using what assembler or compiler? If you are using MPASM (and I am new to this so be gentile if I am wrong)...how about the "fill" directive. From the MPASM help file: <label> fill <expr>, count Generates <count> occurrences of the program word .... <expr> If you used this after the last real instruction in your program then <label> will have the value of the first location you want to zero. The last address depends on the processor type but is certainly known in advance. Call it lastProgramAddress. I assume something like this would work ZeroFill: fill 0,lastProgramAddress - ZeroFill + 1 -Mike {Original Message removed}

on 13/3/02 10:31 AM, Mike Harrison at mikeKILLspamWHITEWING.CO.UK wrote: >> I would like to fill in unused portions of the program memory with a >> specific value (0x0000), > why? Probably because many text books have told him that he should. That should spark a debate! :-) Sean -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestKILLspam.....mitvma.mit.edu

Yes, I had thought of the FILL directive, but due to the nature of the code (tables, code spread over 4 pages) I would need to put in quite a few. I was wondering if their was a more elegant way of doing this using MPASM. I am implementing code to reprogram the microcontroller remotely, and I want to generate a hex file that will set all unused program words to 0x0000. This way I can determine if the code was loaded in the field (since the unused portions contain 0x0000), or if it was loaded at the factory (where unused portions will contain 0x3FFF). {Original Message removed}

No, then I get overwrite errors. -----Original Message----- From: Claudio Tagliola [EraseMEcptagliolaspam_OUTTakeThisOuTCHELLO.NL] Sent: March 13, 2002 9:23 AM To: PICLISTspam_OUTMITVMA.MIT.EDU Subject: Re: [PIC]: filling unused program memory Can't you FILL the complete range as the first MPASM operator, and then ORG back to the beginning? -----Original Message----- From: pic microcontroller discussion list [@spam@PICLISTKILLspamMITVMA.MIT.EDU] On Behalf Of Terence Monteith Sent: woensdag 13 maart 2002 15:57 To: KILLspamPICLISTKILLspamMITVMA.MIT.EDU Subject: Re: [PIC]: filling unused program memory Yes, I had thought of the FILL directive, but due to the nature of the code (tables, code spread over 4 pages) I would need to put in quite a few. I was wondering if their was a more elegant way of doing this using MPASM. -- 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: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

>I am implementing code to reprogram the microcontroller remotely, In the future (not far) I also will reprogram the pic remotely. I though in somethig like send the new code via a telephone mobile module and save it in an external eeprom. Then check if the code is ok and program it in the pic (flash pic). How is your idea? Regards, Carlos -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Isn't this the purpose of erasing a chip before programming? I'm new to this PIC stuff still, but the Tait programmer I'm using seems to state that using the erase command on the same command-line as dumping the hex file to the PIC will erase the chip first and then drop on the code whereever there is code. All mem locations w/o code will not be touched. Cheers. ----- Original Message ----- From: "Terence Monteith" <RemoveMETerence.MonteithTakeThisOuTWAVECOM.CA> To: <spamBeGonePICLISTspamBeGoneMITVMA.MIT.EDU> Sent: Wednesday, March 13, 2002 9:25 AM Subject: Re: [PIC]: filling unused program memory > No, then I get overwrite errors. > > {Original Message removed}

I cannot get into too much detail since ultimately this will end up in someone else's product, but here is a brief explanation. The unit itself is connected to a headend via an RS485 connection, where the reprogramming is controlled from. On the uC is a modified version of a Microchip application note (AN732). In the microcontroller data is received, verified with a CRC, and programmed 16 words at a time. It is then reverified to make sure it was programmed correctly, and then an ACK (or NACK if somewhere the process failed) is sent back to the headend. If an ACK is returned the next 16 words are sent, if a NACK is returned the 16 words that failed are re-sent. {Original Message removed}

Can't you build a custom .HEX file modify program? It shouldn't be too hard to make a program which replaces the 0x3FFF into 0x0000. On another note: you wrote it's for determining a factory or a field load. Do you have to have every 3FFF replaced by 0000? Can't you pick ONE memory location and hardcode a pre-defined value there? You can make it with MPASM using IFDEFs which trigger only for a factory build. {Original Message removed}

>Can't you build a custom .HEX file modify program? It shouldn't be too >hard to make a program which replaces the 0x3FFF into 0x0000. I could but was hoping for an easier way. >On another note: you wrote it's for determining a factory or a field >load. Do you have to have every 3FFF replaced by 0000? Can't you pick >ONE memory location and hardcode a pre-defined value there? You can make >it with MPASM using IFDEFs which trigger only for a factory build. I am thinking I might just have to do this. Thanks for the help. {Original Message removed}

> Yes, I had thought of the FILL directive, but due to the nature of the code > (tables, code spread over 4 pages) I would need to put in quite a few. I > was wondering if their was a more elegant way of doing this using MPASM. You could just post process the HEX file by inserting hard zeros for all values that aren't explicitly specified. > I am implementing code to reprogram the microcontroller remotely, and I want > to generate a hex file that will set all unused program words to 0x0000. > This way I can determine if the code was loaded in the field (since the > unused portions contain 0x0000), or if it was loaded at the factory (where > unused portions will contain 0x3FFF). How about a single ID or version word at a know location, like the last location in memory. ******************************************************************** Olin Lathrop, embedded systems consultant in Littleton Massachusetts (978) 742-9014, TakeThisOuTolinEraseMEspam_OUTembedinc.com, http://www.embedinc.com -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

> Isn't this the purpose of erasing a chip before programming? I'm new to > this PIC stuff still, but the Tait programmer I'm using seems to state > that using the erase command on the same command-line as dumping > the hex file to the PIC will erase the chip first and then drop on the > code whereever there is code. All mem locations w/o code will not > be touched. He wants to set unused memory to 0 (although his reasons seem silly), whereas "erase" implies setting it to all 1s. ******************************************************************** Olin Lathrop, embedded systems consultant in Littleton Massachusetts (978) 742-9014, RemoveMEolinTakeThisOuTembedinc.com, http://www.embedinc.com -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Recognizing that the original question referred to an MPASM solution, an alternate approach would be an offline program to manipulate the .hex file so that zeroes are written to all addresses not otherwise filled. Would take a few hours to write and test the program, but may save time in the long run once the capability exists. Regards, Steve -- 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