topic Re: MPC8315E - PCIe interface in PowerQUICC Processors

MPC8315E - PCIe interface

airazusta — Tue, 07 May 2019 07:31:18 GMT

Hello,

I was wondering how I should disable/enable the SerDes PCIe interface of the MPC8315E via SW. Would be enough to configure SDPD bit of SRDSCR0 register to '1' (Block power down) for disable it?

And should I also make any change in HW? For example, following the application note AN3438, it says that SD_IMP_CAL_TX signal has to be connected to GND using a 100R precision resistor when the interface is used, but when not used it has to be connected to 1V. If I disable the PCIe interface via SW, can SD_IMP_CAL_TX signal still be connected to the 100R resistor?

Thanks in advance!

Regards,

Ane

Re: MPC8315E - PCIe interface

Bulat — Tue, 07 May 2019 11:12:37 GMT

Yes, setting of SRDSCR0[24] bit is enough for powering down (disabling) entire SERDES from SW point of view.

Yes, if SERDES is not used, you can connect both SD_IMP_CAL_TX (and SD_IMP_CAL_RX) to 1V via 100 Ohm resistors.

Regards,

Bulat

Re: MPC8315E - PCIe interface

airazusta — Tue, 07 May 2019 12:13:38 GMT

Thank you for answering Bulat!

And would it be ok if I leave both calibration signals connected to GND via 100 Ohm (or 200 Ohm) resistor when I power down the SERDES?

Regards,

Ane

Re: MPC8315E - PCIe interface

Bulat — Wed, 08 May 2019 01:45:45 GMT

I believe it will be ok. Side effect is that grounded resistors could cause additional unnecessary power consumption.

Regards,

Bulat