Dear forum,
i need a multiplexed 16 bit bus working over CAT5e cable, where 1 master communicate with multiples (up to 32 or more) slaves, with very low latency. Serial buses like Ethernet have too much processing overhead, and i have only the 8 wires (=4 differential pair) of CAT5e.
So my first idea was using a serializer/deserialzer DS92LV18, what offers to serialize a 18 bit bus (16 address/data, 2xmux) over 2 LVDS pairs. Because i have multiple slaves, i think on using M-LVDS or BLVDS, what allows up to 32 nodes. I understand, that my protocol on top of the M/BLVDS must ensure, that only 1 slave send data at one time. That seems doable. The problem on this solution is the maximum cable length: i need up to 10 Meter (more would be even better). So i thought, i can use cable equalizer (DS15BA101SD), or special LVDS driver IC (SN65LVDSxx) every 10 meter. I read a lot of LVDS related documents and application notes from TI, but non of them talk about the usage of a multi-segmented LVDS bus, where LVDS drivers or cable equalizers are between the segments. So my question is: How many of such segments i can concat to a long LVDS bus, before the DS92LV18 looses the synchronization?
To be more specific: The parallel bus would have
16 MHz clock frequency
16 Bit Data/Address lines, 1 address or data flag, 1 TBD line
18bit + 2bit for the embedded clock * 16MHz = 320MBit serialized
The master and each slave would be equipped with 1 DS92LV18 (plus extra LVDS line receiver and extra LVDS line driver [or the cable equalizer]). Between each node up to 10 Meter cable(and even longer cable, if possible). If i could combine up to 20 of such nodes to 1 LVDS bus, i would not even need the multi-drop or bus LVDS, then point-to-point LVDS parts could be used as well, right? Because then each SerDes "see" only a LVDS receiver and a LVDS driver/cable equalizer, and the outer logic ensure, that only 1 SerDes transmit at a time.
I understand, that every LVDS driver or cable equalizer add some delay and jitter. But how many of them i can connect in series, until a DS92LV18(sender) -> driver-> cable -> driver cable .... DS92LV18(receiver) can no longer communicate?
Could anybody help me out on this with an application note or other information, setting up a M/B/LVDS bus with several nodes over CAT5e, over 100 meters or more? Or are there other parts, better suitable for my field of problem?
Thanks (any help is welcomed)
