I'm using a board that's using a Zynq-7000 to communicate with a DP83869HM. The issue I am having is that the device is not responding over the MDIO/MDC bus. The driver that Xilinx has provided loops through all 32 PHY addresses (starting with 31, down to 0), and tries to read register address 00h to determine which devices are out there.
My problem is that PHY doesn't respond to any of the addresses, and I've verified this on an o-scope.
I've used an o-scope to verify the following things:
1) Reset signal is asserted low for almost a millisecond, then deasserted for the remainder of the program
2) The MDIO and MDC lines are making it to the PHY on the correct pins, and look reasonable. MDC is about 500 kHz
3) Both XTAL_IN and XTAL_OUT show a 25 MHz sinusoidal waveform.
4) INT_N/PWDN_N is being pulled high
5) VDDA2P5 measures 2.5V, VDD1P1 measures 1.1V, VDDIO measures 1.8V. VDDA1P8 pins are left floating since we are in "two supply mode."
Any suggestions on things to check or try?
