DP83867IS: MDIO can not work

kevin zhao

Part Number: DP83867IS

After power up, the pin of MDIO is always 0V. When SOC write some datas to PHY, the hign level of MDIO is 1V, can not reach the normal level 1.8V (VDDIO is 1.8V)

Disconnect the R431, the MDIO of PHY to GND is near 1M Ohm when power down and is roughly 60~70 Ohm when power up. I guess the MDIO of PHY is OD output? What's keeping it going to output low level (0V)?

SCH _ 39 Ethernet1 RGMII RJ45.pdf

thanks

over 5 years ago

0 Justin Lazaruk over 5 years ago

TI__Expert 7040 points

Hi Kevin,

Can you verify that there is no pull-up resistor connected to GPIO_0 and provide the register values of 0x6E and 0x6F to verify the strap settings are what you expect?

GPIO_0 must be strapped into mode 1 or 3, per the datasheet, otherwise MDIO may be affected.

Regards,
Justin

0 kevin zhao over 5 years ago in reply to Justin Lazaruk

Prodigy 20 points

Hi Justin,

I removed the 0Ω resistor between GPIO_0 and SOC, it is OK.

Maybe there's a pull-up inside the SOC

Thanks

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DP83867IS: MDIO can not work