Hi,
I have some detailed questions about the Adafruit bootloader and how to get my zephry-compiled binary, and uf2 versions, working with it.
Specifically:
- I have an Adafruit Feather nRF52840 Express
- nRF Connect installation, and therefore a zephyr build environment (under linux)
- An nRF52840-DK board, acting as a segger jlink to the Adafruit nRF52840
I can compile my zephyr app and flash directly to the 0x0000 address and see the application work.
What I want, though, is to have a bootloader, like from Adafruit, which accepts x.uf2 files, so I can upgrade the application later easily. This is where all my problems are, and I could use some help.
My process is:
- erase the nRF52840
- flash the Adafruit nRF52 bootloader
- drag/drop the .uf2 version of my zephyr app
The erase and bootloader flash works fine I think.
But the drag/drop of the .uf2 doesn't lead to a working application. I need help.
Erasing the nRF52840 is this:
JLinkExe -CommandFile erase_command.jls
si 1
speed 4000
device NRF52840_XXAA
connect
erase
exit
Flashing the Adafruit nRf52 bootloader (https://github.com/adafruit/Adafruit_nRF52_Bootloader) is this:
nrfjprog --program _build/build-feather_nrf52840_express/feather_nrf52840_express_bootloader-0.6.4-dirty_nosd.hex --sectoranduicrerase -f nrf52 --reset --verify
Converting my zephyr-built binary is this:
uf2conv.py zephyr.bin -c -b 0x1000 -f 0xADA52840
I chose 0x1000 because reading the source code of the bootloader, I see:
bootloader.c
if ( is_sd_existed() )
{
PRINTF("SoftDevice exist\r\n");
// App starts after SoftDevice
app_addr = SD_SIZE_GET(MBR_SIZE);
fwd_ret = sd_softdevice_vector_table_base_set(app_addr);
}else
{
PRINTF("SoftDevice not exist\r\n");
// App starts right after MBR
app_addr = MBR_SIZE;
sd_mbr_command_t command =
{
.command = SD_MBR_COMMAND_IRQ_FORWARD_ADDRESS_SET,
.params.irq_forward_address_set.address = app_addr,
};
fwd_ret = sd_mbr_command(&command);
}
// unlikely failed to forward vector table, manually set forward address
if ( fwd_ret != NRF_SUCCESS )
{
PRINT_HEX(fwd_ret);
// MBR use first 4-bytes of SRAM to store foward address
*(uint32_t *)(0x20000000) = app_addr;
}
// jump to app
bootloader_util_app_start(app_addr);
nrf_mbr.h
#define MBR_SIZE (0x1000)
So, I upload the converted application, in .uf2 format, by drag/dropping onto the mounted USB drive. The drive accepts it, unmounts itself, and does not re-mount itself.
This indicates to me the program was flashed.
I can confirm this by reading back the flash memory, and I do see my program in its entirety residing at 0x1000.
But why doesn't my program run?
I don't understand enough about the Adafruit bootloader, nor about the zephyr application, to know.
Can someone help me understand what to do differently to get this to work, or to debug what I've tried?
I know my application works when directly flashed to 0x0 (via nRF Connect VSCode plugin).
Any and all help appreciated, thanks!
Doug
