Hello,
Our product is using a DP83869HM IC. We have configured it through the HW straps to SGMII to Copper Mode 1000/100/10, Auto Negotiation, Auto MDI-X.
Also we control the MDIO pins of the DP83869HM and we can read and write to the registers if needed.
An RJ45 connector through magnetics is connected to the PHY of the DP83869HM and the SGMII is connected to an SFP. (This describes our device)
As you can see from the attached block diagram we can successfully connect our Device A with our Device B (Device A is the same product with Device B), when equally speeded devices are connected to the copper sides of our devices.
But our problem is that when a device 1000/100/10Mbps capable is connected to the copper side of our device A and a device 100/10Mbps capable is connected to the copper side of our device B, they are both connected at different speeds.(1000Mbps and 100Mbps).
As a result there is no communication between those 2 devices (as expected). Although, we continue having the same problem even when we select 100Mbps speed (with Auto Neg disable) at BSCR register only for our device A.
We were expecting that the device A will be forced to 100Mbps speed in order to achieve speed matching on both devices. Although this didn’t work.
Is it possible to achieve communication between different speeded devices by downlink the higher speeded device and achieve speed match?
Thank you.