Choosing Bi-port Ethernet Chip
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From: Tomás Ó hÉilidhe on 6 May 2008 19:17 I've searched the web and I've only found two chips that can interface with 2 ethernet ports. They are: AX88742 AX88783 On the manufacturer's website, they describe the 42 variant as: 32-bit PCI 2-Port 10/100M Fast Ethernet Controller And the 83 variant as: Non-PCI 8/16/32-bit 2-Port 10/100M Fast Ethernet Controller Could someone please explain to me what this means? Also, and this probably sounds like a clueless question, but I don't know if either chip is a fully-fledged microcontroller, or whether they're an ethernet controller on its own that needs to be hooked up to a microcontroller? Anyone know?
From: linnix on 6 May 2008 23:53 On May 6, 4:17 pm, Tomás Ó hÉilidhe <t...(a)lavabit.com> wrote: > I've searched the web and I've only found two chips that can interface > with 2 ethernet ports. They are: > > AX88742 > AX88783 > > On the manufacturer's website, they describe the 42 variant as: > > 32-bit PCI 2-Port 10/100M Fast Ethernet Controller > > And the 83 variant as: > > Non-PCI 8/16/32-bit 2-Port 10/100M Fast Ethernet Controller > > Could someone please explain to me what this means? > > Also, and this probably sounds like a clueless question, but I don't > know if either chip is a fully-fledged microcontroller, No > or whether they're an ethernet controller on its own that needs to be hooked up > to a microcontroller? Maybe > Anyone know? Yes
From: robertwessel2 on 7 May 2008 00:04
On May 6, 6:17 pm, Tomás Ó hÉilidhe <t...(a)lavabit.com> wrote: > I've searched the web and I've only found two chips that can interface > with 2 ethernet ports. They are: > > AX88742 > AX88783 > > On the manufacturer's website, they describe the 42 variant as: > > 32-bit PCI 2-Port 10/100M Fast Ethernet Controller > > And the 83 variant as: > > Non-PCI 8/16/32-bit 2-Port 10/100M Fast Ethernet Controller > > Could someone please explain to me what this means? > > Also, and this probably sounds like a clueless question, but I don't > know if either chip is a fully-fledged microcontroller, or whether > they're an ethernet controller on its own that needs to be hooked up > to a microcontroller? Anyone know? These both appear to be combined dual Ethernet switch ports and a (single) Ethernet controller (more or less), with no real intelligence, except for some IP offload processing (and whatever they needed internally for the bridging function). The PCI chip has the electronics to attach to a PCI bus, while the non- PCI one has a more traditional "block of RAM" like interface. If you have a PCI bus on your system, go with the former, if you don't (rather more likely with a microcontroller), go with the latter. The non-PCI version appears to support different sizes of data bus, making it easy to attach to various width microcontrollers. Both of these appear to support some bridging functions internally (hence the word "switch" in the description). In short, it ends up looking like a three port Ethernet switch, with your microcontroller attached to one of the ports. These are not dual port Ethernet controllers in the sense that they connect to different networks. IOW, I don't think you could build a two port router with one of these devices, unless there is a different mode of operation than the one being touted. But there's no particular reason to use a dual port chip, unless one of them happens to fit your needs particularly well. Two single port chips are the more common solution. Or like I mentioned earlier, one internal Ethernet port on your microcontroller plus an external single. If youre looking for a single chip microcontroller with multiple Ethernet ports, look at some of Freescales stuff. For example, the MPC852T has a fast Ethernet port plus two serial controllers that can run a 10Mb Ethernet port each (for a total of three Ethernet ports). |