nrf52832 simple FW updater

RE: nrf52832 simple FW updater

Ivan — Wed, 30 Oct 2019 14:53:32 GMT

Here is memory compare of flashed by degguger and OTA via ESB , than using flash rewrite via RAM function. It's same, and same working, but after OTA flash - no reset.

RE: nrf52832 simple FW updater

Turbo J — Wed, 30 Oct 2019 12:36:23 GMT

[quote userid="71428" url="~/f/nordic-q-a/53732/nrf52832-simple-fw-updater/217478"]Actually I start from this, I call this function in my first example, after rewriting flash. But board won't reset.[/quote]

Maybe Invalid Vector table?

Look at the first 8 Flash bytes after changing firmware. First 4 bytes must be an end of RAM pointer (inital stack pointer) and next 4 bytes must be an odd value for Reset handler with T bit. Remember that the processor is little endian.

RE: nrf52832 simple FW updater

Ivan — Wed, 30 Oct 2019 10:15:41 GMT

As I notice, after flash write, no code is working, I test to trigger some GPIO via non-lib direct functions.
But It works only after erase, but not after rewriting.

RE: nrf52832 simple FW updater

Susheel Nuguru — Wed, 30 Oct 2019 10:09:45 GMT

[quote userid="71428" url="~/f/nordic-q-a/53732/nrf52832-simple-fw-updater/217478"]But board won't reset.[/quote]

That is very strange, if that is true, then you should first investigate what is stopping it to reset. I am not sure if there are some settings in ARM core that could prevent it resetting when using NVIC_SystemReset.

RE: nrf52832 simple FW updater

Ivan — Wed, 30 Oct 2019 09:53:19 GMT

Actually I start from this, I call this function in my first example, after rewriting flash. But board won't reset.
It can be resetted via button no problem, or when I connect a debugger, I get to the entry point.
But it won't done automatically... Now only helps to trigger a delayed reset before FW copy via GPIO output and delayed IC back to HW reset pin...

RE: nrf52832 simple FW updater

Susheel Nuguru — Wed, 30 Oct 2019 09:41:13 GMT

After the final copy from the RAM to flash at 0x0, you need to execute NVIC_SystemReset instead of branching to 0x0.

That way , you wil make sure that all the registers are in proper state to execute the new reset handler from the vector table

RE: nrf52832 simple FW updater

Ivan — Mon, 28 Oct 2019 16:14:11 GMT

I find that flash is correct from 0x0 address, but after rewriting and resetting board, program stays at Reset Handler.
And now is question, how to jump to main() in this case?

RE: nrf52832 simple FW updater

Turbo J — Mon, 28 Oct 2019 13:46:27 GMT

Normal linked firmware contains interrupt vector table at address zero - which does not contain executable instructions but executable addresses instead.

The "switch to firmware" on an ARM Cortex-M is loading the MSP from the 4-byte value at address zero, and then loading the PC from the next four bytes (RESET function address with T bit set). Usually done in assembler since stack is changing.