MSP430F5252: Jump from No RTOS bootloader to TI RTOS Application

Hi Clement,

In regards to your question:

Clement Guillou1 said:

How do I put a BRA to ISR in the proxy vector ?

The way this is done in MSPBoot is as follows:

• The bootloader defines the vector table like this:

/* Value written to unused vectors */
#define UNUSED                  (0x3FFF)       
/*! Macro used to calculate address of vector in Application Proxy Table */
#define APP_PROXY_VECTOR(x)     ((uint16_t)&_Appl_Proxy_Vector_Start[x*2])   // <-- This defines the start of the "application proxy vector table"

// This table must be placed in the interrupt vector location (0xFF80-0xFFFD)
// Note that it doesn't include the reset vector since the reset vector points
// to the start of the bootloader.
const uint16_t Vector_Table[] =
{
     UNUSED,                                     // FF80 = unused
... (more unused vectors)
     UNUSED,                                     // FFD0 = unused
     APP_PROXY_VECTOR(0),                        // FFD2 =  RTC         
... (more defined vectors)
     APP_PROXY_VECTOR(21),                        // FFFC =  SYSNMI      
};

• • Note that it just fills "reserved" locations with a value. 0x3FFF is a "JMP $" which just traps the device.
  • The "valid" vectors are pointing to the corresponding addresses of the Proxy table (i.e. say 0xF000)
  • Reset is not included in the table because it will automatically point to the start of bootloader after building the code.
    
• On the other hand, the application defines its vectors as follows:

// This table should be placed starting at _Appl_Proxy_Vector_Start 
const uint16_t ProxyVectorTable[] =
{
    0x4030, (uint16_t)Dummy_Isr,           // APP_PROXY_VECTOR(0) RTC <-- First valid ISR for device. A Dummy ISR when not used by application
... (Other dummy or defined ISRs)
    0x4030, (uint16_t)P1_Isr,              // APP_PROXY_VECTOR(6) PORT1  <-- Used by application
... (Other dummy or defined ISRs)
    0x4030, (uint16_t)Dummy_Isr,           // APP_PROXY_VECTOR(21) SYSNMI  <-- Last valid ISR (doesn't include Reset)
}; 

• • The table should be placed in a known location (0xF000 based on our example)
  • Note that "0x4030" is the OpCode for a BRA instruction.
  • The "Application reset vector" should also be placed in a known location (i.e. after this table). The address of the reset vector can be adjusted in the linker file (i.e. just as an example 0xF1FE)
  • Note that the proxy table ignores all the "reserved" vectors and only starts on the vector defined as APP_PROXY_VECTOR(0)
    
• MSPBoot always starts executing the bootloader. The bootloader decides if it should stay in bootloader mode or if it should jump to the application. If it needs to jump to the application, it simply grabs the reset vector from the known predefined address of "Application reset vector" (i.e. 0xF1FE based on the example above)

There are other ways to do the proxy table. One option could be just to define Proxy ISRs with a fixed location and use them to jump to the actual ISR. This is less cryptic than using an OpCode.

Regards,

Luis R