Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
11 years ago

88E1111 Marvell PHY Chip Clock

Hi Friends.

This post is about Marvell 88E1111. It's close to impossible getting any information from them.

On connecting the 25MHz crystal to the XTAL1 and XTAL2, does the chip internally generate 125MHz?

There's an output pin 125CLK. Can this be used by my IP as the TxCLK?

Your advise would be helpful to me.

Thanks.

14 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor

    Hi,

    I am new with Altera De2-115 board. I saw there is two marvell PHY chip in DE2-115 board. My plan is used both. One for receiving data and other one for transmitting.

    But I don't know how to identify them first. Second I dont know how to interface the chip to FPGA? I can see that i have to use MDIO in order to do some configuration in PHY chip registers.

    Would someone help me please where to start?

    Thanks in advance
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor

    There is no need to use both, unless you have more data than a gigabit Ethernet can handle. Note that Ethernet is full duplex, meaning each cable has dedicated TX and RX pins so there is no need to separate Tx and Rx into two cables. Trying to get both working at the same time is needlessly complex. Start with one of the examples that uses a single Ethernet and modify it to fit your needs. The Terasic software may not have been tested with both Ethernets in use at the same time. All I've seen are examples where there were separate projects to test each Ethernet.

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor

    Hi Galfonz,

    Thank you for your reply.I dont know how to start with this chip.

    I would like to use MII interface. so i changed the jumper in the board.

    For receiving--

    Do i have to use MDIO to adjust some register in chip to start receiving data?

    CRS gives the signal if the media is active. That means I shoud start to read the RXD where data comes in 4 bit of each clock cycle(RXD_CLK). Am I right?

    Thanks
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor

    This isn't the best board to start learning low level Ethernet with. The 88E1111 is a very flexible chip with a lot of settings that need to be correct before it will work. On top of that, the documentation is only available by contacting Marvell and signing an NDA. Since this is an old chip, and you aren't developing a product that will sell lots of their chips, I doubt they would let you have the documentation. But you can always try. You might also find some clues on the web.

    The only demo for the DE0-115 that uses Ethernet is written for MicroC os-ii which is another commercial product, so it's not available unless you purchase it. So you won't even have working source to use as a place to start.

    In answer to your questions. Yes either MII or RGMII will work. You won't receive anything unless the 88E1111 has been initialized. I think there are 8-10 settings needed. The Ethernet MAC in the FPGA takes care of monitoring CRS and receiving data each clock. I think there are tutorials available on how to set up the Altera Ethernet. It's fairly involved. Your software needs to have receive buffers available. The data will be coming in via DMA.

    My advice would be to use a different board unless your goal is understanding Ethernet. One based on SoC would be nice. You can have Linux take care of Ethernet in the kernel.

    If you do manage to get Ethernet going on the DE2-115 board without the Marvell docs and MicroC source, congratulations. This is not a project for someone new to embedded design.