How to jump to Application 2 from Application 1

[TinhEBD18]

Hello ervery one,

I am doing development on NRF52840. I have a problem as follows looking forward to your guidance.

I need to jump to Application 2 (address: 0x32000) from Application 1 (address: 0x26000). I did not use Bootloader / DFU because it found it quite confusing and did not suit my problem.
I expect when the boot device will run into Application 1 and then jump to Application 2.
Looking forward to your help, thank you!

[Turbo J]

Fist things first: App2 must be linked to address 0x32000 - check the linker settings / linker script.

Secondly use the folowing function to set the vector table base in softdevice:

sd_softdevice_vector_table_base_set(0x32000);

Third: Load the SP and PC from the fist two words at 0x32000 - this starts the actual execution. May need some inline assembly in order to work across all compiler optimization settings.

[TinhEBD18]

Hi Turbo, Tks you for your support.

1, I use KeilC, I don't know if my settings are correct! (This is Application 2, Image bellow) 

2, Call funtion sd_softdevice_vector_table_base_set(0x32000) in application 1? Right

3, This is my code for jump to application 2:

Tks you so much!

void jump_to_application(void)
{
	uartSendDBG((uint8_t *)"Function jump bl\r\n", strlen("Function jump bl\r\n"));
	void (*fn_jump_app)(void);
	uint32_t msp_value = *(volatile uint32_t *)FLASH_ADDRESS_APPLICATION_PRIMARY;
	__set_MSP(msp_value);
	uint32_t resetHandler = *(volatile uint32_t *)(FLASH_ADDRESS_APPLICATION_PRIMARY+4U);
	fn_jump_app = (void *)resetHandler;
	fn_jump_app();
	uartSendDBG((uint8_t *)"Done\r\n", strlen("Done\r\n"));
}

[Turbo J]

Trying to jump to another application in plain C is asking for trouble, but it might work if the compiler optimized the code properly.

I recommend checking the disassembly of jump_to_application() in a debugger.

The problem is that local variables on the stack are no longer accessible once the new MSP value is set.

Edit: The "Done" debug message should be changed to "Failed", since this code cannot be reached.

[TinhEBD18]

Log "Done" not reached on the terminal, the device is hang when I call fn_jump_app()   or  sd_softdevice_vector_table_base_set(0x32000).

[Vidar Berg]

TinhEBD18 said:

Log "Done" not reached on the terminal, the device is hang when I call fn_jump_app() 

 That's because it is branching to the reset handler of application "2". Please post a screenshot of the CPU registers (shown on the left side when you debug in Keil) when the device hangs and post it here. 

[yunzhi]

Hi Vidar Berg.

I have the same problem.

Application 1 can jump to appliction 2  successfully without any ble process.

But when start to perform ble_stack_init(), the program will hang in SVC_Handler.

I tried to add sd_softdevice_vector_table_base_set(APP2_ADDRESS) before ble_stack_init(). It  hanged after this line.

[Vidar Berg]

Hi,

yunzhi said:

But when start to perform ble_stack_init(), the program will hang in SVC_Handler.

 Does it get stuck in the SVC_Handler in your application? In that case, I would expect the same to happen when you call sd_softdevice_vector_table_base_set() as well?