| ECB Ethernet board [message #8043] |
Thu, 22 October 2020 06:43  |
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will
Messages: 213
Registered: October 2015
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Senior Member |
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I've been working on an ethernet board for ECB computers. The board is based around the Realtek RTL8019AS ethernet chip. The board should permit connection to 10Mbit/s ethernet networks using unshielded twisted pair (UTP) cables.
At this stage I have drawn up the schematic but not yet started the PCB layout. I would welcome any comments on the schematic (attached to this post in both PNG and PDF format).
The RTL8019AS chip is a highly integrated network interface chip commonly found on ISA NE2000 cards. It implements a DP8390 NIC clone and the required packet buffer SRAM. It is currently easily obtainable on Ebay for around $3. This is connected to an Amphenol RJMG163118101NR RJ45 jack which integrates a couple of LEDs and all the required transformers, available from Newark, Farnell, Mouser (and probably others) for around $5. An on-board AT93C46 EEPROM holds the configuration for the RTL8019AS including the MAC address. The other components on the board are common 74 series logic and a few passives.
The ECB card can be accessed using 8-bit I/O transfers (no mapped memory). It requires 32 I/O addresses and can be based at any multiple of 0x20. The card's interrupt can be routed to the INT, NMI or IR0 through IR7 pins on the ECB.
My main use for the board will be as an ethernet interface for the KISS-68030 machine running Linux, which already has a mature NE2000 driver. It may also be possible to use the board under DOS on the SBC-188 or SBC-386EX with a suitable NE2000 packet driver. On Z80 and Z180 machines it would be an interesting challenge to implement a TCP/IP stack for the Fuzix kernel, and maybe a TCP/IP library that can be linked in to CP/M applications.
The RTL8019AS uses a 100 pin QFP surface mount package. I anticipate it will be no harder to solder than the SVGA chip on Sergey's ISA SVGA card. I have found QFPs can be soldered with a regular hand held temperature controlled iron, the trick is to use plenty of liquid flux and let surface tension do most of the work.
A note on duplex: The RTL8109AS predates (and so does not implement) ethernet autonegotation. This means that most switches will treat it as a half-duplex device, and so the card must be operated in half-duplex mode. If you have a managed ethernet switch you can statically configure the port to full duplex and then the card can also safely run in full-duplex mode. A duplex mismatch will cause one or both devices to falsely detect collisions. Running the card in half-duplex mode is unlikely be the performance bottleneck on these machines.
[Updated on: Thu, 22 October 2020 08:01] Report message to a moderator |
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| Re: ECB Ethernet board [message #8047 is a reply to message #8043] |
Sat, 24 October 2020 22:01  |
b1ackmai1er
Messages: 396
Registered: November 2017
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Senior Member |
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Hi Will this is awesome.
Since this is a low chip count, how about combining your existing ECB-USB-FIFO design (which I use as my main interface) onto the one board?
In the original USB-FIFO the Adafruit FT232 was quite expensive. How about including either a discrete component version or a capability to use one of the generic units that can be found on ebay or aliexpress. Also, maybe even a wifi interface version.
Regards Phil.
[Updated on: Sat, 24 October 2020 22:02] Report message to a moderator |
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| Re: ECB Ethernet board [message #10197 is a reply to message #9562] |
Sat, 31 December 2022 17:03 |
etchedpixels
Messages: 333
Registered: October 2015
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Senior Member |
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will wrote on Fri, 31 December 2021 10:25Hi Andrew
* Writing a (working, interoperable) TCP/IP stack is hard. The WizNet implements a TCP/IP stack internally, exposing a socket API style hardware interface where you just read/write buffers in the on-chip memory. It will be far easier (more fun) to write software on the Z80 for this chip.
* You can also send/receive raw ethernet frames with the WizNet chips, so it should be possible to use with an OS that implements TCP/IP natively (I'm thinking primarily of Linux on the KISS-68030)
There are a couple of small stacks uIP is tiny (works on 8bit) and LWIP can be set up for 16bit systems fairly easily.
With the raw frames check the docs carefully - the older wiznet can do raw mac protocols but *not* of ip, so you can use the onboard IP and add IPX for example but not afaik do native IP with it. I've only used 5100-5500 though and have a 5300 on my Z80 setup.
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