| ??? 12/27/07 16:00 Read: times |
#148800 - Nobody said anything about a protocol Responding to: ???'s previous message |
Jim Deas said:
RE,
Yea, it's a modulation scheme but I don't know of a UART with a 2x clock out. Guess you could run a PLL off the data stream to create the clock but this is again difficult to get right the first time. It would be easier just to do it with a timer and timercapture unit if you went down that route. Even with this I would be worried about the maximum speed you could obtain over such a crummy cable. The modem scheme has so much more to offer in a single chip. Equalizer, error correction, fall back speeds, compression, etc. No need to reinvent to wheel. These chips are very mature technology. JD If he operates his 805x UART in mode0, and takes the clock that produces and doubles it (flipflops come in pairs, don't they?) He can then double the clock with one flipflop and use that to generate the AMI. How he drives the cable will be pretty much up to him anyway. He's certainly got to make some choices if he's going to run his line over 4 km. If he's imposing any protocol on his comm's, he hasn't mentioned it, and AMI doesn't require one or another protocol. There's a reason the world's telecom systems use AMI for so long, just as there's a reason the telecom companies required a repeater every 4000 feet of cable. These problems have been solved, but there's no reason to assume it will be easy. Further, there's no reason to assume that the original query involved a protocol of any sort. After all, if he can't reliably receive at the remote end what he's sent at the local, a protocol won't help. RE |
