CCS/TMS320F28069M: Why at reset vector location braching instructions is not there ?

Hi Veerendra,

Not very clear on your query. Also the code snapshot is not available in your post. Can you open the disassembly window in CCS and then apply debug reset and check the instruction.

When connected with debugger and load the code (or restart), CCS forces the PC to entry point and start execution from there. Depending on the setting for the entry point in project, execution of ROM code may be skipped.

Regards,
Vivek Singh

Verendra,
The device has the default vector table in ROM populated by factory (TI). On C28, there is NO fetch of instruction from the reset entry location in the vector table, instead the reset entry location of the vector table in ROM contains the address of the boot ROM entry function.

With debugger connected, when you look at the disassembly window, the address where the PC points to on a reset is the entry point function of the boot ROM SW.

Now coming to your other question on how it is works - the device boot ROM execution cannot be skipped when device is powered up. By the time the emulator is connected the device boot ROM would have already executed. Also after a reset (external reset, XRSn) the device boot ROM cannot be skipped when running stand-alone.

With emulator connected when user does a debug reset via CCS, then the device resets and halts at the entry point of the boot ROM SW. Now if user hits run in debugger IDE then device boot ROM is executed but instead if user does a program load (or a restart) then the PC is pointed to the application (user SW) entry point. Defining the application entry point is upto the user and can be done using CCS project properties window. The default TI provided examples use a reset_handler entry point which in turn calls into the _cint00 RTS support library entry point, which in turn calls into the main(). If user doesn't define any entry point to the application then the default _cint00 will be chosen.

Now how does the boot ROM SW, which is always run after the MCU is reset or powered up, calls into the application entry point? This will be explained in the device TRM boot ROM chapter. In short depending on the boot mode the boot ROM ends up branching in to the entry point for the selected boot mode. User is supposed to have the user application entry point here. Users can refer to TI provided examples in ControlSuite or C2000Ware and put the reset_handler routine in the entry point location.


Hope this helps.

Please let us know if you have any further questions.

Best Regards
Santosh Athuru.

Thank you for answer , but the at reset vector location, ididn't find any branching instruction
( i attached the picture below )