10BASE-T ethernet questions.
HollyMinkowski
Posts: 1,398
I'm pretty much all software and just a smidgen of hardware so
I could use some advice on slow speed ethernet hardware.
I was just reading that the slower 10BASE-T system uses only
2 of the twisted pairs of wire in the CAT5 cable.
pin1 - tip - white/orange
pin2 - ring - orange
and this pair
pin3 - tip - white/green
pin6 - ring - green
Firstly, what does tip and ring mean?
It seems that they use -2.5 and +2.5 volts to accomplish the data
signaling on these pairs.
What I am interested in is whether or not a propeller chip could
be used to both send and receive data on these wire pairs?
A sort of low-budget slow-speed ethernet data handling capability.
I just got Jan Axelson's book "Embedded Ethernet and Internet Complete"
and as I read along I just started wondering if the prop could handle
10BASE-T.
If one could use a prop and a few cheap parts to get some sort
of ethernet capability that would be sweet!
I suppose 2 H-Bridge circuits could be pulsed to send the -2.5 | +2.5
signals on the 2 twisted pairs?
It seems like detecting the data coming back from a router with
slower 10BASE-T signals should be do-able ??
So is this silly or possible
The protocol (Manchester Encoding) is a lot more complicated than simpler data schemes like I2C
or RS-485 but it seems like you could manage it on a prop as long as you could do it
quickly enough. I see no reason at all why you couldn't manage it with an ARM in the 500mhz
range but if fast enough the prop would be easier since you have 8 cores and would not
have the hassle of doing everything in interrupt routines.
I understand the prop has a shortage of fast ram to play with... that may be the
biggest hurdle....wish each cog had several thousand longs to play with.
I'm not interested in serving up web pages, just transferring short byte strings
over ethernet.
I can borrow a network analyzer from work, that might make things easier.
I could use some advice on slow speed ethernet hardware.
I was just reading that the slower 10BASE-T system uses only
2 of the twisted pairs of wire in the CAT5 cable.
pin1 - tip - white/orange
pin2 - ring - orange
and this pair
pin3 - tip - white/green
pin6 - ring - green
Firstly, what does tip and ring mean?
It seems that they use -2.5 and +2.5 volts to accomplish the data
signaling on these pairs.
What I am interested in is whether or not a propeller chip could
be used to both send and receive data on these wire pairs?
A sort of low-budget slow-speed ethernet data handling capability.
I just got Jan Axelson's book "Embedded Ethernet and Internet Complete"
and as I read along I just started wondering if the prop could handle
10BASE-T.
If one could use a prop and a few cheap parts to get some sort
of ethernet capability that would be sweet!
I suppose 2 H-Bridge circuits could be pulsed to send the -2.5 | +2.5
signals on the 2 twisted pairs?
It seems like detecting the data coming back from a router with
slower 10BASE-T signals should be do-able ??
So is this silly or possible
The protocol (Manchester Encoding) is a lot more complicated than simpler data schemes like I2C
or RS-485 but it seems like you could manage it on a prop as long as you could do it
quickly enough. I see no reason at all why you couldn't manage it with an ARM in the 500mhz
range but if fast enough the prop would be easier since you have 8 cores and would not
have the hassle of doing everything in interrupt routines.
I understand the prop has a shortage of fast ram to play with... that may be the
biggest hurdle....wish each cog had several thousand longs to play with.
I'm not interested in serving up web pages, just transferring short byte strings
over ethernet.
I can borrow a network analyzer from work, that might make things easier.
Comments
"tip" and "ring" refer to the tip and the cylindrical portion of the 1/4" phone jack/plug used in manual telephone switchboards.
Have you looked at the YBox2? It normally acts as a webserver, but can and has handled other protocols. It can even update itself over the network.
www.ladyada.net/make/ybox2/
www.deepdarc.com/ybox2
It uses that 3.00 microchip ethernet chip.
I was just wondering if the prop could handle
some sort of rudimentary ethernet all by
itself without an ethernet chip or the special
ethernet jack (about 5.00)
I'm getting the data sheet for that microchip
ethernet chip to see what I can discover about
it's usage...there may be some gems buried
inside that document about ethernet data
handling.
The ENC28J60 handles the low level Manchester encode/decode. It does the CRC calculation and provides a buffer and the I/O drivers.
The Ethernet jack provides isolation and impedance matching. If you don't use the jack, you still need the transformers.
the microchip ethernet chip is the best way to go.
Too bad the ENC28J60 has so many bugs.
I glanced at the errata sheet and it was so
long it was almost the size of a data sheet
Maybe they have upgraded the design? I will have to
do more checking.