DP83822HF: Difference between some type Resets

Hello Takumi Suzuki1

Thank you for the query.

Please see below. I would additionally suggest to look through the datasheet for more information.

Hardware reset ( clears all registers, used during power up or to reset full device, detect strap configuration)
This pin is an active low reset input that initializes or reinitializes all the internal registers of the PHY.
The DP83822 uses the receive path functional pins as bootstrap options to place the device into specific modes
of operation. The values of these pins are sampled at power up or hardware reset, through either the RESET pin
or bit[15] in the PHY Reset Control Register (PHYRCR, address 0x001F).

Software reset ( resets PHY PCS registers, used where ever soft reset is specified)
Writing a 1 to this bit resets the PHY PCS registers.
One of the use case is:
TI recommends connecting Signal Detect pin from the Optical Transceiver to the LED_1
pin and enable it using SD_EN bootstrap pin in 100BASE-FX mode. The LED_1 pin is not
used in design and that, if the electrical link between the fiber module and the DP83822 is
broken, disconnected or otherwise disrupted, the link will recover only by initiating a soft
reset through MDIO/MDC interface.

Digital Restart ( resets the digital circuitry, no effect on registers, could be used for diagnostics)
This bit is self cleared and resets all PHY digital circuitry except the registers.

Regards,

Sreenivasa

Hello Sreenivasa-san,

Thank you very much for your reply.

Let me understand well your answer.

My understanding is as below, is my idea correct?

 - Hardware reset : by using 18pin(= low), reset all registers, bootstrap options detect

 - Software reset : 0x001F(PHYRCR) Bit15=1 set, just only reset PHY PCS register (= Not all)

 - Digital reset : 0x001F(PHYRCR) Bit14, reset digital circuits, no effect on all registers

And will you tell me what register of this device is "PHY PCS" register?

I appreciate your support.

Best Regards,

Hi Sreenivasa-san,

Thank you so much for your reply.

I understood.

Thanks and Best Regards,