M
myst1
Guest
Hi,
I've got the following problem: I want to decode what's going on on an
interface between two devices running on a quite old D2B bus by Philips
(copper-based, not optical). Everything I
know about this bus comes from some vague info on web pages (i.e. that it
is an offspring from I2C and that it uses difference voltage logic). Most
info I have found is in the datasheet of the MSM6307 (avail. at
http://elenota.iele.polsl.gliwice.pl/upload/msm6307.pdf).
What I can read from the two-paragraph specs about the D2B bus is, that it
represents a HIGH by a voltage difference of more than 120mV and a LOW by
a voltage difference lower than 20mV.
Now the question - how to convert this voltage differences to CMOS/TTL
logic? For the beginning I was considering the following solutions:
1) AC/DC converter (only for first examining of the protocol and
debugging) and microcontroller. But I'm not sure whether I'll get the
appropriate sampling speed.
2) some LVDS receiver chip used for converting to TTL. The chips I've seen
(e.g. at national semiconductors) have different characteristics from the
D2B specs:+100mV difference is HIGH, -100mV is LOW. Depends now on the D2B
bus driver, how close does it conform to the specs, right?
The MSM6307 controller is, in my opinion, not very well suited for
snooping another transmission since it already contains all logic for
frame decoding, slave addressing and so on. I even dunno the slave address
of the receiving device (I have not had the possibility to check the parts
and layout for both devices yet - as soon as I can, I can give more info
on them).
Are there maybe other solutions? Maybe you have more info on the D2B
bus handy?
Thanks for help in advance,
--
myst1
I've got the following problem: I want to decode what's going on on an
interface between two devices running on a quite old D2B bus by Philips
(copper-based, not optical). Everything I
know about this bus comes from some vague info on web pages (i.e. that it
is an offspring from I2C and that it uses difference voltage logic). Most
info I have found is in the datasheet of the MSM6307 (avail. at
http://elenota.iele.polsl.gliwice.pl/upload/msm6307.pdf).
What I can read from the two-paragraph specs about the D2B bus is, that it
represents a HIGH by a voltage difference of more than 120mV and a LOW by
a voltage difference lower than 20mV.
Now the question - how to convert this voltage differences to CMOS/TTL
logic? For the beginning I was considering the following solutions:
1) AC/DC converter (only for first examining of the protocol and
debugging) and microcontroller. But I'm not sure whether I'll get the
appropriate sampling speed.
2) some LVDS receiver chip used for converting to TTL. The chips I've seen
(e.g. at national semiconductors) have different characteristics from the
D2B specs:+100mV difference is HIGH, -100mV is LOW. Depends now on the D2B
bus driver, how close does it conform to the specs, right?
The MSM6307 controller is, in my opinion, not very well suited for
snooping another transmission since it already contains all logic for
frame decoding, slave addressing and so on. I even dunno the slave address
of the receiving device (I have not had the possibility to check the parts
and layout for both devices yet - as soon as I can, I can give more info
on them).
Are there maybe other solutions? Maybe you have more info on the D2B
bus handy?
Thanks for help in advance,
--
myst1