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Altera_Forum's avatar
Altera_Forum
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20 years ago

Different number of address pins

The LAN91c111 chip has 15 address pins. The NIOS II module for LAN91c111 has 16. How do I have to connect the pins? What&#39;s about the remaining pin? http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/blink.gif

I&#39;m using quartus 4.2.

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    I don&#39;t know if it is an answer to your question, but when I looked at the standard reference designs, I noticed that the reset_n_to_the_lan91c111 isn&#39;t connected.

  • Altera_Forum's avatar
    Altera_Forum
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    I think I was a little bit unclear.

    The lan91c111 chip has 15 address bits [15..1]. But my SOPC module generates 16 [15..0] address bits. The other pins are OK.
  • Altera_Forum's avatar
    Altera_Forum
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    The reference designs in the Nios II kits don&#39;t have reset_n_to_the_lan91c111 connected because the MAX part on the PCB is controlling the reset. If you don&#39;t have such a setup then you would have to use it. Also I forget if that chip used reset_n or reset (the lan controller in SOPC builder used to export the wrong polarity). So check the data sheet of the lan91c111 to determine if you should throw an inverter on the reset signal or not.

    Because the controller is hooked up to the tri-state bridge, those addresses are byte addresses (15..0). The chip uses 16 bit wide data so just use the top 15 bits when you wire it (take a look at the schematic for the Nios development boards and you will see this wiring).