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TM4C129ENCPDT: EMAC LPI support

Klaus Breining64693
Intellectual 550 points
Part Number: TM4C129ENCPDT

Hello,

in the Peripheral Driver Library as well as in the sample ethernet driver there is a "EEE" mode rsp. "LPI" support. In the sample code it is commented out (#ifdef EEE_SUPPORT), in the header files the registers are mentioned (EMAC_O_LPICTLSTAT, EMAC_O_LPITIMERCTL). However the debugger as well as the datasheets don't mention the registers. So far, so good, it seems on the device this feature doesn't exist. Now I tried in the debugger to fill in values into these registers and they respond as expected in the documentation (as far as I can understand from the "TivaWare Peripheral Driver Library").

Is this feature not documented for some reason (maybe having some bugs)? Or is the documentation not updated with later SoC masks? Would be at least interesting for me, as currently I do power-management by simply switching between 100Base-T and 10Base-T, which saves a lot of energy.

Regards

Klaus

  • 0
    TI__Guru**** 191826 points

    Hi Klaus,

      I don't have the history of the documentation as to why this feature was removed. When a feature was removed, I believe there is an intention behind it. But I am guessing that the EEE (Energy Efficient Ethernet) was removed because it is a LPI (Low Power Idle) feature requiring an external PHY with RGMII interface for which the Tiva device does not support. Please do not use any features that are not mentioned in the datasheet.