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RPI and WIFI SD to deploy new bootcode.bin,...

Posted: Sat Mar 22, 2014 9:15 am
by msperl
Hi!

I thought of start investigating a "freeware" bootloader/FreeRTOS setup for the RPI (as a I doubt that linux will be possible due to the limited MMU capabilities of VC4 itself).
Actually my first Idea would be trying to port uboot...

To avoid having to manually unplug/replug the SD Card every time I update the Firmware images I thought of using one of those (hackable) Transcend WIFI-SD Cards (e.g.TS16GWSDHC10) to update the files in /boot on the fly and then trigger a reboot of the RPI.

Has anyone been successfully doing that?

Thanks, Martin

Re: RPI and WIFI SD to deploy new bootcode.bin,...

Posted: Sat Mar 22, 2014 11:41 am
by duberry
msperl wrote: Has anyone been successfully doing that?
No! , but apparently* with modle A its possible to boot over usb link



*i have not 'successfully doing that'.

Re: RPI and WIFI SD to deploy new bootcode.bin,...

Posted: Mon Mar 24, 2014 10:33 am
by hldswrth
An alternative, cheap and simple option is to use the Pi's built-in UART, and a 3.3v USB to Serial converter to establish a serial link to a PC and then have the boot loader download the kernel image via the serial link.

With a wifi-enabled SD card I assume you can just copy the files to the card over the wifi link and reset the Pi to reboot with a new image.

Re: RPI and WIFI SD to deploy new bootcode.bin,...

Posted: Tue Mar 25, 2014 6:41 am
by msperl
hldswrth wrote:An alternative, cheap and simple option is to use the Pi's built-in UART, and a 3.3v USB to Serial converter to establish a serial link to a PC and then have the boot loader download the kernel image via the serial link.
True: uboot can do that for the arm portion, but I am talking about videocore bootloader /boot/bootcode.bin and /boot/start.elf.

If I want to replace those the arm-uboot loader will not help me downloading them via serial line, as those files are loaded/executed before arm gets started and uboot gets loaded...

That is: unless there is some serial loader inside the pre-bootloader, which loads /boot/bootcode.bin and which is stored on the bcm2835 chip itself

Re: RPI and WIFI SD to deploy new bootcode.bin,...

Posted: Tue Mar 25, 2014 9:50 am
by tufty
I would imagine it would be possible to write a pre-bootloader that runs as bootcode.bin, relocates itself out of the way, then listens on a UART for a new bootcode.bin, and transfers control to it. Much of what's needed to do this is already on Herman's github.

Going the whole hog and writing a new bootcode to the SD card is going to be a far more intensive task.

On the other hand, we already have JTAG pins for the GPU, so you might well be able to use those instead.