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adding bootloader05

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2012-09-13 23:29:06 -04:00
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See the top level README file for more information on documentation
and how to run these programs.
Derived from bootloader03, this is a very simple bootloader. Instead
of the sd dance (see toplevel README), this makes life a bit simpler
and greatly reduces physical wear and tear on the sd card socket. Do
the sd card dance one more time with kernel.img. Get some sort of serial
solution to connect a dumb termial program with xmodem capabilities
to the uart on the raspberry pi. (see the toplevel README for more
information).
The difference between bootloader03 and bootloader05 is very subtle,
first I dont like the config.txt thing and didnt want bootloader04 to
be the biggest numbered bootloader. Second I use minicom and lrzsz
as a dumb terminal and for xmodem transfers, there is a delay as
lrzsz is ending and returning back to minicom so there is a delay.
Bootloader05 has a loop that prints some numbers before it branches
to the downloaded program.
You take the .bin file of your test program, assumed to be built based
on address 0x8000 and less than 0x200000-0x8000 bytes in size.
With uart connected to a terminal
1) power off raspberry pi
2) power on raspberry pi
3) use xmodem to transfer binary file
Repeat for each new program to test
This bootloader sits at 0x200000 so that you have 0x200000 bytes to
develop with. And that way if you like your program you can just
copy a .bin version to kernel.img on the sd card and use it. Fairly
easy to change this address. bootloader05.c and vectors.s each have
a copy of this value. bootloader04 uses a rasberry pi specific
config file to move much deeper in memory giving you much more room
if you want more room use that bootloader.
bootloader01 uses .hex files, bootloader02 through bootloader05 use .bin
files, .hex files wont work. Consider bootloader01 and 02 to be
obsolete.
I normally do not deliver binaries. In this case I have included all
of the build files so that you can at least get started without having
to build the bootloader. Backup whatever kernel.img file you are using
and replace with the kernel.img file in this repo (on your sd card).