i.MX6DQ GPIO_16 pin to use IEEE1588 and JTAG.

[satoshishimoda]

Hi community,

I have some questions about i.MX6DQ IEEE1588 and JTAG.

Please see my questions as below.

[Q1]

Please see revision history in MCIMX6DQ-SDP schematics.

It says "Moved I2C3 SDA from GPIO_16. This pin must be unconnected for Ethernet 1588 (time stamp) functionality to work".

Next, please see ERR005895 in IMX6DQCE (Rev.4).

It says "Due to an integration issue, the ENET 1588 clock and Channel 2 event capture/compare signal are both connected to the same GPIO16 pin.".

According to this description, GPIO_16 is not unconnected for Ethernet 1588.

Which is correct?

[Q2]

GPIO_16 pin is muxed JTAG_DE_B also, and JTAG_DE_B and ENET_1588_EVENT2_IN cannot replace to other pad.

So customer can use either of the two function, is this correct?

Or user should assign GPIO_16 pad to JTAG_DE_B if they want to use both JTAG and IEEE1588 since GPIO_16 is not able to be used for IEEE1588 by ERR005895?

Best Regards,

Satoshi Shimoda

[Yuri · Accepted solution]

  GPIO_16 should be left free in order to use internally generated 1588 clock, since

the internally generated 1588 clock signal is actually routed through the GPIO_16 pad.

When GPIO_16 ALT 2 is selected, the PAD is connected to an internal signal.

  This means other multiplexing options for this pin should not be used simultaneously

with Ethernet 1588. More details may be found in the next thread.

“GPIO_16 configuration for IEEE-1588 operation when using Gigabit Ethernet
PHY with RGMII interface”

https://community.freescale.com/thread/322451

Have a great day,
Yuri

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