RE: Understanding booting; SD not handling SVC

Vidar Berg — Tue, 04 Feb 2020 08:36:38 GMT

Hi Bert,

The NRFFW[0] register is used to signal the MBR that a bootloader is present, and at what address it starts at. And when a bootloader is present, the MBR will not invoke the Softdevice but forward execution and interrupts directly to the bootloader (or application in this case) effectively bypassing the Softdevice. That is why the SVC interrupts are not being processed but forwarded to the application with this register configuration.

You can invoke the Softdevice from your bootloader by issuing the following MBR command:

sd_mbr_command_t com = {SD_MBR_COMMAND_INIT_SD, };

/**< Init forwarding interrupts to SD, and run reset function in SD*/

err_code = sd_mbr_command(&com);
APP_ERROR_CHECK(err_code);

/* Change Softedvice interrupt forwarding address if it is different from the default starting address (0x19000 for this Softdevice) */

err_code = sd_softdevice_vector_table_base_set(<vector table address>);
APP_ERROR_CHECK(err_code);

You can also read more about the MBR and the startup sequence in the SDS here: Master boot record and bootloader. I hope this helps. If anything is unclear, let me know.

Kind regards,

Vidar