C166 : startup with a loader

Hello,

If my understanding is correct, you do not want to use the standard built-in bootstrap loader but rather a custom solution which you have named "bootloader", too.

Let us remember that the built-in bootstrap loader must be loaded via UART from outside counterpart s/w into the internal RAM at FA40h, and is only 32-byte wide; typically there are 2 more bootstrapping stages: 2nd one loads bigger f/w code still into the internal RAM, and then this second code loads the main boot application into (external) RAM. This is the 3d part which takes care about erasing/writing/reading flash and/or eeprom, etc.

Anyway, the built-in bootstrap mechanism assumes that the UART is being used (or CAN for some MCU steps) - which is not your case. Pay attention, the bootstrapping f/w should be run from within the RAM in order to erase and write flash.

So in other words, it is possible to have this scenario:

Start at reset vector (0h)
Jump to <User address>
Check flash
Branch either to:
 a) main application - run it,
    or
 b) custom bootloader, part #A (1/2) - run it
In case b):
 - the #A copies another part #B (2/2) from flash to RAM
 - the #A transfers control to #B (sits now in the RAM)

As a result, this is the #B who actually provides bootstrapping service.

Note that both #A and #B are stored in the flash, but the #B - just as an array of codes. That is, this custom bootloader #B should be build in assuption it will run from RAM, not from flash - but, will reside in the flash. All of this involves additional steps when working with Keil. Look at the application note #138 (In-system FLASH Programming with C16x/ST10) for more details on technical side:
http://www.keil.com/appnotes/docs/apnt_138.asp.
It tells how to use compiler and linker to move program code into RAM for execution while loading flash PM.

Regards,
Nikolay.

Hello,

If my understanding is correct, you do not want to use the standard built-in bootstrap loader but rather a custom solution which you have named "bootloader", too.

Let us remember that the built-in bootstrap loader must be loaded via UART from outside counterpart s/w into the internal RAM at FA40h, and is only 32-byte wide; typically there are 2 more bootstrapping stages: 2nd one loads bigger f/w code still into the internal RAM, and then this second code loads the main boot application into (external) RAM. This is the 3d part which takes care about erasing/writing/reading flash and/or eeprom, etc.

Anyway, the built-in bootstrap mechanism assumes that the UART is being used (or CAN for some MCU steps) - which is not your case. Pay attention, the bootstrapping f/w should be run from within the RAM in order to erase and write flash.

So in other words, it is possible to have this scenario:

Start at reset vector (0h)
Jump to <User address>
Check flash
Branch either to:
 a) main application - run it,
    or
 b) custom bootloader, part #A (1/2) - run it
In case b):
 - the #A copies another part #B (2/2) from flash to RAM
 - the #A transfers control to #B (sits now in the RAM)

As a result, this is the #B who actually provides bootstrapping service.

Note that both #A and #B are stored in the flash, but the #B - just as an array of codes. That is, this custom bootloader #B should be build in assuption it will run from RAM, not from flash - but, will reside in the flash. All of this involves additional steps when working with Keil. Look at the application note #138 (In-system FLASH Programming with C16x/ST10) for more details on technical side:
http://www.keil.com/appnotes/docs/apnt_138.asp.
It tells how to use compiler and linker to move program code into RAM for execution while loading flash PM.

Regards,
Nikolay.

Thanks for your reply.

I will only use flash boot (no bootstrap via CAN or SSC).

I find this http://www.keil.com/support/docs/2389.htm witch can help me.

For me, execute flash programming functions in RAM is forbidden : I need to be able to run event if a power supply occurs during SW update.

I will investigate with linker options (L166_Locate & L166_Misc tabs) to have the possibility to have 2 startup files into my micro.

thks, Nick.

Hi np,

your bootloader project looks like similar to my project. I write a C-program that loads an hexfile from the Office-PC to the XC167 via serial-interface. After calculating the Cheksum of the hexfile it will be written to the on-chip flash beginning at address 0xC02000. To run the hexcode from the on-chip flash i had to jump to the main routine, which i located at address 0xC02800.
In my project i use the same startup-file for the bootloader and the downloaded application. So I'm not confronted with the problem of to startup files.
Problems occurs when i modify the vector segment register and jump to the application-main routine:

PSW_IEN   = 0 ;
VECSEG=0x00C1;
((void (far *) (void)) 0xC02800) ();

At the address 0xC02800 first the interrupts are activated and an endless loop waits for data from the serial interface. This works good but any other interrupts like timer or IIC don't work.

Please post me when you made similar eperience. Mayb we can compare some notes about this kind of application.

Greetings