P3 Bootloader update
2005-03-04 by colinfraser_com
Folks,
As I've mentioned previously, future production of P3 will be using
a new CPU, the AT89C51ED2, that has replaced the T89C51RD2 part I
have used up to now.
Due to differences between the original CPU and its replacement, a
revised sysex bootloader is needed for firmware updates.
So that I don't have to build separate firmware images for old and
new processors, I have provided a bootloader update image that will
install a new bootloader on your T89C51RD2 based P3.
ALL FUTURE RELEASES OF THE P3 FIRMWARE WILL REQUIRE THIS UPDATED
BOOTLOADER.
The update process is as painless as I could make it, and should be
foolproof, i.e. you will not be able to leave your P3 in an
unbootable state. If you somehow manage this, I can re-flash your
CPU by post.
You'll find two files in the Yahoo files section:
p3-bootloader-v3-T89.syx and
p3-bootloader-v3-T89.txt
Follow the instructions in the txt file when you come to do the
upgrade.
Note that you only need to do this upgrade the next time you want to
update your main program. If progress makes you nervous, no need to
bother.
I have also decided to revise the P3 firmware version numbers, since
I'm rapidly approaching v3.999, and still have space to add stuff ;-)
So the next release is v3.1.000 (the previous build being v3.0.988)
This release doesn't change anything significant - it is just
relocated in memory to suit the new bootloader.
I am yet to test the operation of the new CPU with a 24MHz crystal,
which I will do before I publish the new Bill of Materials.
There's no reason why the 33% CPU speed increase should cause a
problem, so I will specify this processor speed for all future P3
kits if I can.
The new bootloaders for old and new CPUs have a stored value to
define the crystal speed for each processor type - this will allow a
common main program to adjust its baud rates to suit either CPU.
Cheers,
Colin f