ENET-1588 PTP with hardware timestamp

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ENET-1588 PTP with hardware timestamp

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neusch
Contributor II

i.MX6 RGMII connect to Ethernet PHY with IEEE-1588 support


Infos:

Hardware Development Guide for i.MX6
Tabele 2-9 Gigabit Ethernet Recommendations

Peter 17.04.2014
"Now back to the 1588 question. Does it mean that the IEEE 1588 needs a separate
50MHz clock which needs to go through GPIO_16 regardless whether where the
125MHz reference clock for the RGMII is routed?"

Weidong 26.05.2014
"1588 timer has compare function,  set ENET_TCCRn register to generate 1pps from 1588_eventx_out."

Justin 23.06.2014
"we are working with Freescale to get a releasable version of the required support firmware
available, but this may take some time - think three to six months from now"

"Hardware - you have to have one of the1588_event_out pins available from the iMX6 to get
the Event Out signal. This is specified in the iMX6 RM"

Are these hardware requirements for Linux Kernel higher 3.10 are correct?

- 125MHz reference clock on ENET_REF_CLK from external oscillator or PHY
- A no connect GPIO_16 to use the internal 50MHz for time stamp clock
- connect for Master ENET_1588_EVENTx_OUT to external PHY for 1PPS
- connect for Slave ENET_1588_EVENTx_IN from external PHY for 1PPS

Thanks

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weidong_sun
NXP TechSupport
NXP TechSupport

Hi Matthew,

    The following answers for you as a reference:

----------------------------

About 1588 ts clock:

1588 ts clock must come from GPIO_16/RGMII_TX_CTL PINs,  since you use RGMII mode, so the only method is from GPIO_16.

From internal:

SOC PLL6_enet -> GPIO_16 -> loopback to 1588 ts clk.

From external:

External clock (from phy/ OSC) -> GPIO_16 -> loopback to 1588 ts clk.

25, 50, 100, 125 Mhz clock are all ok for 1588 ts clock

-----------------------------

Regards,

Weidong

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gregshay
Contributor I

Hello Weidong,

Your statement:

About 1588 ts clock:

1588 ts clock must come from GPIO_16/RGMII_TX_CTL PINs,  since you use RGMII mode, so the only method is from GPIO_16.

Where does this specification come from?  I want to use external 1588 ts clock, and the reference manual does not document this GPIO_16 function?

Regards,

Greg Shay

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Yuri
NXP TechSupport
NXP TechSupport

Hello,

  Please use section 23.3 (External Signals) of the Reference Manual.

ENET_1588_EVENT signals are used for PPS signals.

 

  Also, please be aware about item ERR005895 ENET ( ENET 1588 channel 2
event capture mode not functional) of the Errata.

 

< http://www.nxp.com/assets/documents/data/en/errata/IMX6DQCE.pdf >

 

As for the reference clock :

 

1) External ENET clock source option: A 125 MHz reference clock is required to
feed the ENET_REF_CLK input.
2) On-chip ENET clock source option: A 125 MHz reference clock (derived from PLL6)
must feed the ENET_REF_CLK input.

 

  Please consult with Table 2-9 (Gigabit Ethernet Recommendations) of the
Hardware Development Guide for more details.

 

< http://cache.nxp.com/assets/documents/data/en/user-guides/IMX6DQ6SDLHDG.pdf >

 

Regards,

Yuri.

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neusch
Contributor II

Hello Weidong,

thanks for the Information about the clock.

It is a difference between hardware timestamp in MAC or in PHY and should be evaluate.

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