DP83822HF: MDC and MDIO connection

Hi Kelvin,

The table connections you show above are correct between the KSZ and 822 are correct for RMII.

The DP83822HF does not require MDIO/MDC for operation, the PHY can be configured through hardware bootstrap only.

Also, the table for bootstraps above is correct if the MAC you are connecting to does not have internal pulls.
However, looking at the KSZ datasheet the MAC pins have internal pulls, which will fight the internal pulls of the PHY as well as the external pulls.
Please compensate accordingly to get the correct threshold voltage as found in the Electrical Char table within the DP83822 datasheet.

SMTXER3 (RX_ER) has an internal PU
SMTXD31 (RX_D1) has an internal PU
SMTXD30 (RX_D0) has an internal PU
SMTXEN3 (CRS_DV) has an internal PU

HiRoss，

After modified the pull-up and pull-down resistor as below table, but the problem cannot be solved.

We would like to know for the RMII sleave mode,  Are both RX_ER and  CRS_DV is optional connect to  MAC pin?

We would like to know the 83822 chip what is time to read the bootstrap pins after reset from low to high?

Hi Support team,

We did measure the voltage of the RX_DV ( pin26 ). it should be closed to VDDIO, But we measured the pin is  0V and force the reset pin to low, this pin voltage will change to 2.7V . However,  this pin should  be config the 50MHZ clock and RMII mode. Please advise with thanks!

Regards

Kelvin Lo

Hi Support team,

When we set the bootstrap pins voltage by pull up and pull down reisitors, we measure the strap voltage is always is 0V, except pin 17 while providing the power to chip. But forcing the Reset to low, then can measured the strap voltage as above table mentioned. Is it normal?

Regards
Kelvin Lo

Hi Kelvin,

Only when the PHY is in POR or RESET, will the pin be sampled.
RESET is an active LOW, which makes sense that you see the correct voltage when RESET is LOW.

Hi Ross,

1. We would like to know when the PHY set as RMII slave mode,   Does need to connect both RX_ER and  CRS_DV  to the MAC IC ?

2. How to check the MAC to PHY connection is the right connection or not? any method or tools can be used?

3. Until now, it is  still not working, there is no signal coming from pin 9 to pin12  ( currently no physical connection to the router, that mean those pins are open )

Please advise with thanks!

Regards

Kelvin