EK-TM4C123GXL: Tivaware Bootloader / Debug Application Intvecs

Adam Parker

I am developing a Tivaware Booloader based CAN bootloader and associated application. The bootloader is fairly well behaved so I've begun more serious development of the application. The problem I ran into was in my application under debug when I got a CAN message it would drop to an unknown interrupt handler rather than my specified one. Eventually I realized the register which points to the intvecs (NVIC_VTABLE) was at the bootloader intvec position instead of the application one. Manually entering the address of the application intvec into the register seems to have helped. During normal operation, the bootloader appears to handle setting up the application intvecs (correct me if I'm wrong) but I cannot find a setting to set the intvecs position during debug.

So there in lies my question:
How do I use the application intvecs (non 0x0 address) during debug?

over 5 years ago

0 Bob Crosby over 5 years ago

TI__Guru 72500 points

First, is this the CAN bootloader you are using?

https://www.ti.com/lit/pdf/spna244

I do not expect the bootloader to behave differently just because you are in debug mode. After both the bootloader and the application are loaded, try doing a "System Reset" from the debugger. This should cause the bootloader to run, but it sees you have a valid application so it jumps to the application. This should act just like a power-on reset.

0 Adam Parker over 5 years ago in reply to Bob Crosby

Intellectual 680 points

I never found that document, this is the one I went off of.

https://www.ti.com/lit/an/spma074a/spma074a.pdf

As to the solution:

Slightly roundabout but it does work.

Thanks,

Adam

0 Adam Parker over 5 years ago in reply to Bob Crosby

Intellectual 680 points

Bob Crosby

After further thinking about the fact I may not want to go through the bootloader every time I debug (think, a more complex bootloader that might fail). I came up with the following code to manually set the NVIC_VTABLE. Is this sane?

#ifdef DEBUG
    extern uint32_t g_pfnVectors;
    *((uint32_t*) NVIC_VTABLE) = (uint32_t) &g_pfnVectors;
#endif

Thanks,

Adam

0 Bob Crosby over 5 years ago in reply to Adam Parker

TI__Guru 72500 points

That is fine. You don't even need to do the conditional compilation as it will not be an issue to write the NVIC_VTABLE twice with the same value. (Written once by the bootloader, then again by the application.

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EK-TM4C123GXL: Tivaware Bootloader / Debug Application Intvecs