RDRAM: Difference between revisions
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1. Estimate the value of CCi in manual mode which gives a V<sub>OL</sub> almost equal to V<sub>REF</sub>. |
1. Estimate the value of CCi in manual mode which gives a V<sub>OL</sub> almost equal to V<sub>REF</sub>. |
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This can be done by writing increasing CCi values in manual mode and accumulating the weighted difference CCi * (memtest80 - previous_memtest80) for CCi = 0..N (N being the first value of CCi which allows to read all 80 bits during memtest80; N <= 63). |
This can be done by writing increasing CCi values in manual mode and accumulating the weighted difference CCi * (memtest80 - previous_memtest80) for CCi = 0..N (N being the first value of CCi which allows to read all 80 bits during memtest80; N <= 63). |
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This weighted sum of CCi*(memtest80-previous_memtest80) for CCi = 0.. |
This weighted sum of CCi*(memtest80-previous_memtest80) for CCi = 0..N, divided by 80 (minus 0.5 to account for accumulation/rounding errors) is an estimate of CCi which gives V<sub>OL</sub> ~ V<sub>REF</sub>. |
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2. Multiply this value by 2.2: doubling the CCi value, with 10 percent margin, should give a reasonable estimate of CCi such that V<sub>OL</sub> is symmetric to V<sub>OH</sub> with respect to V<sub>REF</sub> (eg. it maximizes signal margin). |
2. Multiply this value by 2.2: doubling the CCi value, with 10 percent margin, should give a reasonable estimate of CCi such that V<sub>OL</sub> is symmetric to V<sub>OH</sub> with respect to V<sub>REF</sub> (eg. it maximizes signal margin). |
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