Re: Booting MPC565 by CAN/RS-232?

Hi David
       Thanks for the tips. Just to make sure my understanding is 
right, I need to transfer the boot code from ROM to RAM when I detect 
a boot message is received over RS-232/CAN. My current implementation 
all I have is a hard RCW which enables the code to execute from 0x0 
in flash, and I use a standard MPC565 with no external flash, so I 
just modified the cfg and lcf files. I simply load the program using 
CodeWarrior on the flash location and then erase/program flash.
Now how do I modify my existing settings and how can I possibly 
detect message and reflash it. I am new to writing bootloaders and it 
doesnt look so straightforward to me!! Can you please send the 
bootloader code which you have used so that I can understand how I 
can possibly accomplish this task?! Are there any standard bootloader 
code available so that I can make use of that for my development. 
Thanks again.
Regards
Vijay

--- In [email protected], David Wybo <realtimeconsultants@c...> 
wrote:
> It is fairly straightforward, but there are a couple caveats. First 
you 
> need a device driver for the port you want to flash from. However, 
if 
> you are reflashing the internal flash, and your vector table is in 
this 
> internal flash, then you need to be very careful about an interrupt 
> river device driver, since at some point in time, you will be 
erasing 
> the vector table. So, you can either programmatically move the 
vector 
> table to some other memory, or run a polled device driver.
> 
> Secondly, the code you are executing in order to do the download 
must 
> execute from somewhere, and it also cannot be executing out of the 
> internal flash while you are trying to reprogram it. So, either 
this 
> code, I'll call it the bootloader, needs to be moved from internal 
flash 
> to RAM, or it needs to execute from external flash, or it needs to 
be 
> downloaded into RAM at the point in time when you want to reflash.
> 
> The bootloader I wrote a while back, accepts a new application over 
CAN. 
> WHile the old application is running, a message is sent to the 
target 
> stating that a reflash is requested. The message is acknowledged, 
and 
> the bootloader is downloaded into RAM. WHen the bootloader is 
completely 
> downloaded, the application terminates and jumps to the bootloader, 
> which then communicates to the host to download the new application 
for 
> flashing. I happen to use CCP for the protocol, but you can use 
anything 
> you want.
> 
> Keep in mind that with only 8 byte data packets, CAN bootloading 
may 
> take longer than a serial download. However, the time needed to 
reflash 
> a 2 Mb application over CAN is not that bad. I also use an RTOS but 
that 
> also is not necessary.
> 
> Hope this helps.
> 
> vijayanandl wrote:
> 
> >Hi All,
> >      I have a question regarding programming the internal flash. 
In my 
> >current implementation I have programmed the MPC565 internal flash 
> >using the JTAG interface. We have a working system now and to 
expand 
> >its functions, now I am interested to program the internal flash 
using 
> >the RS-232/CAN interface if possible. The question is I am 
currently 
> >using the standard initialization, with program executing from 
internal 
> >flash and I do not use an RTOS(its a bareboard) my environment is 
> >Codewarrior and BDI. So what are the steps I need to take to 
achieve 
> >this capability using RS-232/CAN interface? 
> >Do I need to modify my initialization files, flash driver etc. 
Advice 
> >in this regard will be really helpful. Thanks in advance.
> >
> >Regards
> >Vijay
> >
> >
> >
> >
> >
> >-----------------------------------------------------------
> >To learn more about Freescale Microcontrollers, please visit
> >http://www.freescale.com/mcu
> >
> >
> > 
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> >
> >
> >
> > 
> >
> >
> >
> >
> >  
> >
> 
> -- 
> David Wybo                    mailto:david.wybo@r...
> RealTime Consultants, Inc.    Phone: 248.345.6160
> www.realtimeconsultantsinc.com




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