Hello, I am trying to make an in house bootloader for a home project.
I made a program that just blinks an LED on and off every 500ms verified it works had keil generate the hex file transferred that file over to my pi where I have a script that sends it out to my NRF52 (M4) line by line and waits for an acknowledgement telling it that the CRC was valid and data was written correctly.
I have written all the data from the hex file to its corresponding area in flash starting at 0x4000 and all looks well in the memory window. I receive the second to last line with a data type of 5 (start linear address). From my understanding this is where I jump to to start my new application. I take that address and add my bootloader offset of 0x4000 so it corresponds with the rest of the flash that I wrote. The problem is that it just jumps off into no mans land. I have no idea why. r0 holds the address I want and expect and I can see my instruction set at location 0x4519;
I have tried this code from keil with no success http://www.keil.com/support/docs/3913.htm
Here is the code I am running. I receive this line from telling me where to jump. :0400000500000519D9 I interpret this as jump to location 0x0519... my offset of 0x4000 so I jump to 0x4519.
I am also reading the first and last line of the hex file but throwing it away first line = :020000040000FA last line = :0000001FF
__asm void binexec(uint32_t *address) { bx r0 }
__asm void binexec(uint32_t *address) { mov r1, r0 ldr r0, [r1, #4] ldr sp, [r1] bx r0 }
(I have tried both of these binexec files neither have worked)
void BootJump(uint32_t *Address) {
int i;
//binexec(Address); // -- Disable interrupts // Disable IRQ __disable_irq(); // Disable IRQs for (i = 0; i < 8; i ++) NVIC->ICER[i] = 0xFFFFFFFF; // Clear pending IRQs for (i = 0; i < 8; i ++) NVIC->ICPR[i] = 0xFFFFFFFF; // -- Modify vector table location // Barriars __DSB(); __ISB();
// Change the vector table SCB->VTOR = (( uint32_t )Address & SCB_VTOR_TBLOFF_Msk);
//__set_MSP( Address[ 0 ] ) ; // Barriars __DSB(); __ISB();
//( ( void ( * )( void ) )Address[ 1 ] )( ) ; // -- Enable interrupts //__enable_irq(); // -- Execute application binexec(Address);
}
Thank you,
Eric Micallef
Breakpoint and walk into the code (disassembly view), should look like your Reset_Handler, keep going till it dies or you end up in some while(1) loop for the Default_Handler or HardFault_Handler..
Make sure you're enabling IRQs when you get there, and if you have code in SystemInit() that's changing the VTOR.
hi,
Thank you for your reply! I have stepped through the code and as soon as I BX I just fall into the abyss. at my addres 0x4519 the system init is there in the disassembly view I just am unable to jump there for some reason :'(
Small update. I manually changed the PC register in keil to where I wanted to go (0x4519) and it jumped to my application but then in the assembly initialization it jumped back to the for loop that disabled the interrupts in the Bootjump.
Did I flash some instructions wrong? The instructions looked good in the memory window. Could it be because I threw out the first and last lines of the hex file?
Sounds more like you are building the code at the wrong base address. Go into the target settings and advance the IROM base to 0x4000 so the code is linked at the right location.