Transfering data from the App to the bootloader

RE: Transfering data from the App to the bootloader

Hung Bui — Mon, 04 Jul 2016 11:23:12 GMT

@Lee: Besides sharing data via RAM, you can also use Flash. If you don't write any data in bootloader and only read, you can directly access the address on flash and read the data from there. There is no restriction on doing that when the softdevice is active.

RE: Transfering data from the App to the bootloader

lee — Fri, 01 Jul 2016 13:34:48 GMT

Thanks Wojtek, I'm using gcc not Keil unfortunately. I presume the process is pretty similar though.

RE: Transfering data from the App to the bootloader

Wojtek — Fri, 01 Jul 2016 13:31:46 GMT

Are you using keil? What i did using keil is:

set separate RAM memory section in target options (IRAM2, set proper addresses there and tick NoInit)
prepare modified scatter file for linker and modify it according to previous step, in my case it is:

RW_IRAM2 0x2000F000 UNINIT 0x00001000 { *(NoInit) }
static data_t data attribute((section("NoInit"), zero_init));
enable ram retention on chip ofcourse

And when you do similar settings in both app and bootloader, you may have similar addresses of the variables. but it will be much safer if you just put ex. pointer of the location of these variables in fixed place in RAM - somewhere in Keil manual it is described how to use attribute to do it...

in gcc it is data_t data attribute ((section(".noinit")));

I think data should not be static. however i am not sure.

RE: Transfering data from the App to the bootloader

lee — Fri, 01 Jul 2016 13:24:40 GMT

Thanks. I'm not sure how I can do that I've tried adding attribute((section(".noinit"))) static data_t data; to both the app and bootloader. I then set data to a value in app but the value is 0 when read from the bootloader. I guess I have no guarantee that the variable 'data' uses the same memory address in the bootloader as it does in the app. Is this the problem in your opinion? Do you know how I can solve it?

RE: Transfering data from the App to the bootloader

Wojtek — Fri, 01 Jul 2016 10:25:38 GMT

You can use ram retention for that, you don't have to use flash.