AW: RE: 5213 bootloader

Hi Pat
 
If you are using a serial interface for loading new code there is no
reason for keeping the old code also in FLASH (this is only useful if SW
uploads are remote – via Internet for example – where a failure could
otherwise leave the device in a state which inhibits further
communication).

A boot loader via serial interface will require about 4..6k of space so
you will have no problems with your application size.
 
The boot loader is independent of the OS used. It must simply ensure
that the new code is loaded to the correct location (this is defined in
the SREC) and then passes control to it (it needs to be able to jump to
the start address of the new code – which can be a fixed address for
simplicity – eg. start of first unused FLASH sector after the boot
code). The application will need to have its interrupt vectors in SRAM
(which is probably the case with MQX-Lite anyway) because the boot code
must have its vector table fixed in FLASH starting at 0x00000000 so that
it can handle the reset. VBR is set by the application to where its own
interrupt vectors are stored.
 
Regards
 
Mark
 
 
 
Mark Butcher Bsc (Hons) MPhil MIEE
 
M.J.Butcher Consulting                
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Switzerland          <http://www.mjbc.ch/> www.mjbc.ch /
<http://www.utasker.com/> www.uTasker.com
056 491 48 10 / 079 402 26 37 / Skype: M_J_Butcher
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-----Ursprüngliche Nachricht-----
Von: [email protected] [mailto:[email protected]]
Im Auftrag von Patrick Flannery
Gesendet: Dienstag, 29. Januar 2008 00:31
An: [email protected]
Betreff: [ColdFire] RE: 5213 bootloader
 
Wendi, Mark, Steve,
 
Thank you all for your timely responses. 
 
I didn't think that the RTOS that the application is using made a
difference to a bootloader program so I didn't mention it in my original
email. We are using a MQX RTOS for the MCF5213 known as MQX-lite. Is the
RTOS that the application is using important? I thought once it was
compiled it became part of the S19 file produced by the Code Warrior
compiler. The bootloader I had envisioned would receive the S19 file a
sector at a time thru the serial port, store it in SRAM, and then flash
it into the 5213 flash. Am I oversimplifying what's required?
 
1. the bootloader reads a minimum flash sector size (2k) of the new
application into SRAM through the serial port;
2. it flashes that into the next sector of the 5213 flash. 
3. steps 1 and 2 are repeated until the new application has been fully
received and flashed.
 
The 5213 flash is 256k and my application is above 220k so there isn't
room to keep a copy of the old application stored anywhere in case the
flash of the new application is unsuccessful. Since the hardware design
is fixed and can't be changed, adding an external memory isn't possible.
I realize this isn't the optimum method but I inherited the design and
it's fixed due to safety approvals required by the application.
 
Pat
 
 
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