Post by thread:[PIC] PIC32 running a program entirely from RAM

Hi All, I need to run a program on the PIC32 entirely from RAM. This way we could reflash the bootloader app on the flash if needed by loading a program directly into RAM via USB or Setrial port and then executing that rather than the program on flash. The C32 compiler provides a ramfunc keyword to run specific functions in RAM but I am not very clear on how one would run an entire program from RAM. One thought I am planning on trying out is to modify the linker file so all address are in RAM and see if that would work - however I wanted to check with the collective wisdom of the piclist to see if anyone has already done that or something similar? Thanks Mik

Usually, you can update your bootloader and your firmware when they are both on flash. I'm not sure if I understood well, but if you load your software in ram, what will happen if you lose power ? Sorry, I can not help you to place the program on ram, I don't know how to do it, but I'm not sure it is a very "safe" idea. Regards! Kris ________________________________ From: Mike snyder <spam_OUTmsnyder19TakeThisOuTgmail.com> To: Microcontroller discussion list - Public. <.....piclistKILLspam@spam@mit.edu> Sent: Wednesday, May 2, 2012 1:51:51 PM Subject: [PIC] PIC32 running a program entirely from RAM Hi All, I need to run a program on the PIC32 entirely from RAM. This way we could reflash the bootloader app on the flash if needed by loading a program directly into RAM via USB or Setrial port and then executing that rather than the program on flash. The C32 compiler provides a ramfunc keyword to run specific functions in RAM but I am not very clear on how one would run an entire program from RAM. One thought I am planning on trying out is to modify the linker file so all address are in RAM and see if that would work - however I wanted to check with the collective wisdom of the piclist to see if anyone has already done that or something similar? Thanks Mik

What I do when I need to update the bootloader is to create a special application that carries the new bootloader's code embedded in itself. First the bootloader programs the updater and runs it. The first action that the updater does is to replace the reset vector so the old bootloader is deactivated. Then the updater programs the new bootloader. If everything went well, the application installs the new reset vector and erases the magic number that tells the bootloader that there is a valid application and resets the processor. Isaac Em 3/5/2012 11:40, kris duff escreveu: {Quote hidden}> Usually, you can update your bootloader and your firmware when they are both on flash. > > I'm not sure if I understood well, but if you load your software in ram, what will happen if you lose power ? > > Sorry, I can not help you to place the program on ram, I don't know how to do it, but I'm not sure it is a very "safe" idea. > > Regards! > > Kris > > > > ________________________________ > From: Mike snyder <msnyder19KILLspamgmail.com> > To: Microcontroller discussion list - Public. <.....piclistKILLspam.....mit.edu> > Sent: Wednesday, May 2, 2012 1:51:51 PM > Subject: [PIC] PIC32 running a program entirely from RAM > > Hi All, > > I need to run a program on the PIC32 entirely from RAM. This way we > could reflash the bootloader app on the flash if needed by loading a > program directly into RAM via USB or Setrial port and then executing > that rather than the program on flash. > > The C32 compiler provides a ramfunc keyword to run specific functions > in RAM but I am not very clear on how one would run an entire program > from RAM. One thought I am planning on trying out is to modify the > linker file so all address are in RAM and see if that would work - > however I wanted to check with the collective wisdom of the piclist to > see if anyone has already done that or something similar? > > Thanks > Mike

On 5/2/2012 1:51 PM, Mike snyder wrote: > The C32 compiler provides a ramfunc keyword to run specific functions > in RAM but I am not very clear on how one would run an entire program > from RAM. One thought I am planning on trying out is to modify the > linker file so all address are in RAM and see if that would work - > however I wanted to check with the collective wisdom of the piclist to > see if anyone has already done that or something similar? > > Thanks > Mike There is a program that someone has written to implement a form of BASIC on the pic32 and it runs programs in ram that are typed in by the user. You might look at the source for that and see how it was done. http://www.pic32.byvac.com/pic32_intro.php Mark Hanchey

> On 5/2/2012 1:51 PM, Mike snyder wrote: >> The C32 compiler provides a ramfunc keyword to run specific functions >> in RAM but I am not very clear on how one would run an entire program >> from RAM. One thought I am planning on trying out is to modify the >> linker file so all address are in RAM and see if that would work - >> however I wanted to check with the collective wisdom of the piclist to >> see if anyone has already done that or something similar? >> >> Thanks >> Mike > > There is a program that someone has written to implement a form of BASIC > on the pic32 and it runs programs in ram that are typed in by the user. > You might look at the source for that and see how it was done. > http://www.pic32.byvac.com/pic32_intro.php > > Mark Hanchey I suspect tokenized Basic is stored in RAM while the interpreter remains in flash. I think the original poster is looking at running the bootloader in RAM so he can overwrite boot flash. This, to me, is dangerous, but I guess it could be done. You could end up with a dead box with nothing in flash. What I've done on PIC32 bootloading is to have the application write the new code to external SPI flash. When the entire new code has been written to external flash, a call to a simple (ideally, error free) function in boot flash copies the external flash back to the application area internal flash. To allow for things to go wrong, I also keep a copy of the factory application code out in the external flash. Holding a certain button combination on power up copies the factory code back to the application flash so you can try again. Harold -- FCC Rules Updated Daily at http://www.hallikainen.com - Advertising opportunities available! Not sent from an iPhone

Mark Hanchey wrote 2012-05-03 22:08: > On 5/2/2012 1:51 PM, Mike snyder wrote: >> The C32 compiler provides a ramfunc keyword to run specific functions >> in RAM but I am not very clear on how one would run an entire program >> from RAM. One thought I am planning on trying out is to modify the >> linker file so all address are in RAM and see if that would work - >> however I wanted to check with the collective wisdom of the piclist to >> see if anyone has already done that or something similar? >> >> Thanks >> Mike > > There is a program that someone has written to implement a form of BASIC > on the pic32 and it runs programs in ram that are typed in by the user. It (the "BASIC") probably *reads* "programs" from RAM and runs them in flash. The RAM only stores the BASIC statements, not the BASIC interpreter as such. To the PIC32, the BASIC statements in RAM is not "code", it is "data"

On 5/3/2012 4:25 PM, Harold Hallikainen wrote: > y > I suspect tokenized Basic is stored in RAM while the interpreter remains > in flash. I think the original poster is looking at running the bootloader > in RAM so he can overwrite boot flash. This, to me, is dangerous, but I > guess it could be done. You could end up with a dead box with nothing in > flash. > > > Harold > In quite a few of the Mips based processors in things like DVD players they are set up with two different loaders. The first is installed in non volatile ROM and loads the real boot loader. The first boot loader application doesn't have very many functions , just tftp options, or transferring the boot loader code from other sources. This is a sample from such a player showing how it first loads the permanent CFE application that then loads BUPE the real bootloader application . Using CFE you can replace BUPE but CFE remains intact. '' BCM74430010 Setting NAND Params CFE starting from ROM Starting code in RAM Booting Secured uCFE... BCM97601 B0-BSEC uCfe v2.1.22 (CFE core v2.1, BSP_REV 22), Endian Mode: Little Build Date: Mon Jan 25 15:37:45 EST 2010 (kdasu@stb-mhtb-04) Copyright (C) Broadcom Corporation. DDR : Bank0:128MB@400MHz | Bank1:256MB@400MHz NAND Boot : FlashSize 512MB on CS0, BlkSize 128KB, PgSize 2048B NAND vendor timing : addc1095 HYNIX HY27UF084G2B SLC t1(33535238) t2(80000b78) BUPE bootline< boot -elf flash0.cfe.0: >Loader:elf Filesys:raw Dev:flash0.cfe.0 File: Options:(null) Loading: 0x87000000/22500 0x870057e4/127 0x87005880/2227 0x87007efc/596020 0x87099740/288 0x87099860/542800 Successfully loaded secure elf image.... Entry address is 0x87000000 Starting program at 0x87000000 "" It is very similar to what you suggest with the SPI flash. Mark