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Recommended PHY for RGMII

Added by Mark Kraft over 9 years ago

I have recently begun a design-in of the 3359 module to an existing product. I am at a point where I will address the ethernet interface. I see looking thru the forum that there is a limitation when selecting the PHY to be used with this module. An RGMII is only interface available due to the dedication of pins for an RMII interface.

Is the VSC8601 used on the eval board readily available? Digikey has discontinued it. Are there any other PHYs that have been used with this module that can be recommended.

There is a cost impact with the Gig PHY as well as higher pin count in some cases.


Replies (8)

RE: Recommended PHY for RGMII - Added by Michael Williamson over 9 years ago

Hi Mark,

We just kitted a build for DevKits and were able to get the VSC8601 less than a week ago, however I do see that the parts are being discontinued at least on Digikey.

A quick search on Avnet indicates there are some Marvell as well as Broadcom parts that support RGMII. I don't know how readily available they are. We may need to deal with this as well on our next run or DevKit boards -- we have an action to investigate this and I will be sure to follow up.

If you don't require NAND on the SOM, we are in the process releasing some variants of this module that do not have it installed. Several customers do not require it as they are using other boot media such as MMC and would like to have a lower cost option. With the NAND and support circuits removed, you can free up the GMII2_RXERR (currently GPMC_WP_N used for NAND WP) and GMII2_CRS (currently GPMC_WAIT0 used for NAND control). This would allow you to use MII2 or RMII2 and use a 100 Mbit PHY. Having only 1 pin-mux option for these pins (on either MII interface) has really given us some headaches here as well.

If you are interested in this option, please give us (really Tom Catalino or Omar Rahim) a call and they can provide you with the details.

-Mike

RE: Recommended PHY for RGMII - Added by Mark Kraft over 9 years ago

My design will use the MityArm3359 to replace a module recently obsoleted by another manufacturer. I have a limited time frame to prevent production interruption and so would like to minimize impact of hardware redesign and on software changes as well, i.e. tweaking an ethernet driver. BSP with known working hardware is obviously a plus.

Any possibility of using an alternate I2C on the module rather than I2C1 to free up the necessary pins?

RE: Recommended PHY for RGMII - Added by Michael Williamson over 9 years ago

We have / are considering I2C0, but it would be a functional change compared to our currently fielded modules as would tie up those addresses on I2C0 which may conflict with customer designs. It would also require a separate set of bootloader code (we need to read the factory PROM to determine the DDR settings, etc.). Haven't sorted that out yet.

-Mike

RE: Recommended PHY for RGMII - Added by Mark Kraft over 9 years ago

I understand. Thanks Mike.

I will look into the use of MMC, there appears to be some advantages. On top of all this is we are waiting for a Windows version. Our current product is CE based. I have been in discussion with CL here and that BSP is in process with Adeneo. I am not linux saavy but I did browse thru boot user guide to get an idea of the process for using MMC.

RE: Recommended PHY for RGMII - Added by Michael Williamson over 9 years ago

Here is our source for the Vitesse part. We are checking on status of the part for obsolescence.

http://wpgnet.wpgam.com:8000/WPGWebsite/inventory.php?tPart=VSC8601&x=0&y=0

-Mike

RE: Recommended PHY for RGMII - Added by Mark Kraft over 9 years ago

Hi Mike,

Just wanted to follow up on status of obsolescence.

Thanks

RE: Recommended PHY for RGMII - Added by Michael Williamson over 9 years ago

At the moment, this part does not appear to be obsolete, but Digikey is dropping it.

we are discussing an alternate part here, but for now are staying with it. I'll let you know when I know more.

-Mike

RE: Recommended PHY for RGMII - Added by Joseph Orender about 9 years ago

Would it be possible to hook up the LAN8710 onto the AM3359 SOM? I looked at a BeagleBone schematic, but there are a few pins that do not appear to be available as they might be tied up to other peripherals. For example, pin 147 on the header is dedicated to I2C1_SDA and I need to use it as rmii1_crs_dv.

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