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JDeff's avatar
JDeff
Icon for New Contributor rankNew Contributor
5 years ago
Solved

How to switch Transceiver transmitter PLL

I am following the user guide to switch transmitter pll sources. I read register x117(3:0) and get x"B'". I then do a read-modify-write to register x111. but before I modify, the read value is x"78...
  • CheepinC_altera's avatar
    CheepinC_altera
    5 years ago

    Hi,

    As I understand it, you have some inquiries related to the TX PLL switching in the Native PHY. I believe you are referring to A10 devices. If yes, as I understand it from the user guide, to switch to tx_serial_clk0, the 8 bit mapping should be:

    {~logical_PLL_offset_readdata[3], logical_PLL_offset_readdata[1:0],logical_PLL_offset_readdata[3], logical_PLL_offset_readdata[3:0] }

    With the read back value = 0xB -> 4'b 1011, after encoding, the value should be 8'b 0111 1011 -> 0x7B instead of 0xFB. Please help to correct me if I have encoded this incorrectly.

    Thank you very much.

    Best regards,

    Chee Pin

CheepinC_altera's avatar
CheepinC_altera
Icon for Regular Contributor rankRegular Contributor
5 years ago

Hi,

As I understand it, you have some inquiries related to the TX PLL switching in the Native PHY. I believe you are referring to A10 devices. If yes, as I understand it from the user guide, to switch to tx_serial_clk0, the 8 bit mapping should be:

{~logical_PLL_offset_readdata[3], logical_PLL_offset_readdata[1:0],logical_PLL_offset_readdata[3], logical_PLL_offset_readdata[3:0] }

With the read back value = 0xB -> 4'b 1011, after encoding, the value should be 8'b 0111 1011 -> 0x7B instead of 0xFB. Please help to correct me if I have encoded this incorrectly.

Thank you very much.

Best regards,

Chee Pin

JDeff's avatar
JDeff
Icon for New Contributor rankNew Contributor
5 years ago

Yes that was my mistake. I did not realize ~ notation meant NOT bit 3. It now works correctly. Thank you