Frequently Asked Questions
1 Compiling/Programming
1.1 What compiler did you use?
1.2 Where do I get the most up to date versions
of the Ethernet Drivers?
1.3 I have found a bug, how do I report it?
1.4 I am trying to run the driver code as a complete
interrupt routine, but when I send a packet, the NIC stops responding. What
is happening?
1.5 From a PC, you can get ethernet statistics from the
card, but it is not in your driver, why?
1.6 The buffers take up 3.5k aprox. Can I reduce this
overhead to reduce the amount of RAM I use?
2 Ethernet
2.1 The MAC Address of the card is displayed on the computer,
but I cannot ping the card. Whats wrong?
2.2 The NIC works correctly for a time, then stops
sending out packets, what happening?
3 Miscelaneous
3.1 Do I have to pay to use this driver?
3.2 Are you going to keep on developing the code
for this and other NICs?
1.1 What compiler
did you use?
The compiler used to create this driver was Cross-32 Meta-Assembler, Version
4.01. The web site for more information is here.
1.2 Where do I get
the most up to date versions of the Ethernet Drivers?
Currently at the moment, any updated drivers will be availiable through
this tutorial until such time as I get a home page. You can download if
you click here.
1.3 I have found a bug, how
do I report it?
Email the details of the bug to here,
including what it does, and I will advise, resolve or include in the next
update to the software.
1.4 I am trying to run the
driver code as a complete interrupt routine, but when I send a packet, the
NIC stops responding. What is happening?
You cannot run the driver as an all in one interrupt routine. The interrupt
routine can only service the NIC as far as getting a Packet from the ring
into RAM, or signalling the micro that it has finished transmitting. You
must use a flag to signal when a packet has arrived, and then process the
packet. The example code supplied with this driver shows an example of its
use. You cannot call SendPacket from within the interrupt routine, as it
requires to call the same interrupt during its use.
1.5 From a PC, you can get ethernet
statistics from the card, but it is not in your driver, why?
Because we are using a microprocessor that only has a limited amount of
memory and code space, this was left out of the driver as it is not essential
for its operation. There are no plans to incorporate it into the driver
at this stage. If you would like it implemented, then drop me a mail.
1.6 The buffers take up
3.5k aprox. Can I reduce this overhead to reduce the amount of RAM I use?
You can reduce the amount of RAM that is required to use this code. This
can be acheived by using the Receive buffer as a transmit buffer. When a
packet is received from the NIC, the ei_RXD flag is set. You could then
change the packet around as you like, then send the packet. Once the packet
has been sent, the ei_RXD flag can then be cleared, and EIGETPACKET called
to retrieve the next packet from the NIC. Also, you can reduce the amount
of memory being used, while still maintaining seperate send/receive buffers
by reducing the maximum buffer size for the send/receive packet. Note that
if you do this, you should implement the MTU/MRU function in the ICMP protocol.
This allows other devices to ask the microprocessor what its MTU/MRU sizes
are such that it doesn't send a packet greater than the receive buffer.
2.1 The MAC Address of the card is
displayed on the computer, but I cannot ping the card. Whats wrong?
There are many problems that may cause this symptom. The most common are
listed below.
- Check to make sure that the cable connecting the card to the network
is good. If it is a coax cable, make sure that the network is terminated.
If it is 10BaseT, then there should be a link light up on the hub and on
the network card if it has one. If only one of the lights are active, then
there is probably a cable problem.
- If you connecting the ethernet cable directly between the computer
and the NIC, is it a cross over cable? If you are connecting two devices
togeather without a hub, you need to use a cross-over cable.
- Has the network card be set to Auto-Sense the type of network cable.
Some auto-sense cards incorrectly select the network type. It is best to
force it to be the type of connection that you are using, i.e. COAX, 10BaseT.
- If you have link lights on both ends of the cable, when you ping the
card, do you see the activity light on the hub flash? Is so, then something
is being sent from the card.
- If you are using Windows 95, Windows 98, or NT, use the ARP command
to see if an entry exists for the IP address programmed into the NIC. The
command syntax is arp -a. If so, then it has received this information
for the microprocessor.
- Is the IP Address of the NIC, in the same network address space as
the computer you are using to Ping it? If they are not on the same subnet,
then the NIC will not respond.
2.2 The NIC works correctly
for a time, then stops sending out packets, what happening?
This may happen on a loaded network or where the network card is receiving
packets faster than the microprocessor can process them. The packets are
stored in the NIC is a round robin queue, and removed from the queue only
as fast as the microprocessor is instructed. If the head pointer reaches
the tail pointer, then the card will generate an interrupt to signal this
and turn the receiver off in the NIC. This is undesireable, but unavoidable.
This will most likely happen when the card is on a busy network where it
needs to service a lot of requests.
3.1 Do I have to pay to use
this driver?
This driver is currently freeware. You are free to use this code and modify
the code to suit your needs. However, if you modify the code in any way,
then I will may not support any problems you may experience. I request that
should your project go into production and you use this code, that my name
appears somewhere in the documentation. I would also like to know what your
project does for reference. Also, No warranty is also expressed or implied.
The author is not liable for any damage caused by the use of this code.
3.2 Are you going to
keep on developing the code for this and other NICs?
It is my intention to continue to develop this code, and remove any bugs
that may be present. Because there are many chipsets out that emulate the
8390 chipset, some bugs, may make themselves known to certain network cards.
In fact, looking in the Linux Code and certain other codes, there are many
workarounds for certain problems on some NICs. I hope to incorporate some
of these into the code as a conditional compilation during the continued
growth of this driver.
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