Jumping Between Applications

[Ashlesh]

hey guys i want to implement two separate application programs on the same chip.

Say Application1 is stored in address start_address1 to end_address2 and Application2 is stored in address start_address2 to end_address2.

can i just directly jump to one application to another ? i am used to using this on simpler microcontroller, can i do this in the NRF52 too?

void JumpToApp(void) {

void (*fptr)(void);
fptr = (void (*)(void))APP1_RESET_ADDRESS;
fptr();

}

thanks.

[Hung Bui]

Yes, you can do that.

[AmbystomaLabs]

Everyone has been discussing whether or not the vector tables work out.

So just to be clear, you are saying that Ashlesh can call sd_softdevice_vector_table_base_set(SECOND_APP_START); Then do a software driven reset and everything will work out, correct?

It looked to me that all the ISR vectors are driven off of offsets from the base application start. But, if anything isn't driven from an offset and is instead set to an actual address then this method won't work.

[Hung Bui]

Hi AmbystomaLabs, The main vector table is still point into the softdevice vector table. Normally the softdevice will forward those interrupt that's available to the application to the application vector table, which is located at the start address of the application. sd_softdevice_vector_table_base_set() can change that and change the forward address to the address set in the call. Using this you can branch directly to the reset handler of the 2nd application you want to run.

This is the same mechanism we used to jump from application to bootloader and vice versa in our legacy bootloader. (Check bootloader_app_start() function in the bootloader or bootloader_start() in buttonless application in SDK v11)

[Wasil]

Hi Ashlesh,

              I am struggling with s322 and DFU. Can you tell me what should be the target settings? I can debug that after after dfu it say jumping to : 0x0029000 but doesn't start application. Thanks

[AnhLe]

Hi Hung Bui,
In case of not using softdevice is there anyway that I could change the vector table ????( I mean the softdevice and mbr are still there but I don't want to use the softdevice api)
I'm thinking like after jumping to application and the application will do the sd_softdevice_vector_table_base_set.