The Winbond Vocal POST chip contains its own processor. It can
run on a completely stripped motherboard.
Any idea what the processor is? Intel, motorola, or ?
I wonder what the issues are in building a board like that because the
processor executes code initially then, at some point, hands execution off
to the cpu.
-g[/QUOTE]
It doesn't share with the AMD CPU. It has a fixed task, which is
to monitor some hardware error signals (such as the signal that
tells it no CPU is in the ZIF socket), and it also has a queue
for software events delivered by the main CPU. When there are
no other components installed in the board, about all it can
do, is tell you "No CPU installed". The vast majority of
other error messages are only emitted at the command of the
main CPU (which is AMD AthlonXP in this case).
It is very slow - an instruction executes in 400 microseconds.
And this datasheet, like others from Winbond, doesn't do the
part justice. It doesn't describe how to program the device.
That is something I had to figure out, by looking at a couple
of files that come with the Voice Editor software (and I
didn't understand very much of what I saw). That
software is downloadable from the Asus site.
Datasheet for the Winbond chip:
http://www.winbond-usa.com/products/winbond_products/pdfs/PCIC/W83791SDSGa.pdf
The two Voice Editor files are listed here:
http://groups.google.ca/group/alt.comp.periphs.mainboard.asus/msg/af9eb7c50228db72
The main processor communicates with it via I2C, which is the
same thing as SMBUS. SMBUS only runs at 10Kbits/sec, which again
means that communications from the Athlon processor, to the
Winbond chip, is slow as molasses.
The Winbond chip has a timer, and can deliver a Voice message if
the timer times out. Some of the tests that the main processor
carries out on the motherboard, involve setting the timer inside
the Winbond, and then starting the test. If the code on the
main processor crashes, the timer on the Winbond expires, and
a voice message is delivered. If the main processor test code
completes OK, the main processor clears the timer on the Winbond
chip, so no error message is emitted. So, while the Winbond chip
is semi-intelligent, it cannot run the whole motherboard. For
the rest of the error messages, the main processor writes a number
in the queue of the Winbond, and the Winbond then plays that
particular voice sample.
The part is dirt cheap, and appears on a lot of the "deluxe"
versions of Asus motherboards. It is handy for debugging, but
not as good as being able to see port 80 error codes.
Paul
