SNLA364C March 2021 – June 2022 DP83TD510E
The ALCD will need to be calibrated to each cable type and application by measuring the ALCD register information at five regular intervals up to the maximum cable reach the application requires. The calibration can be done in a designer's lab during product evaluation. A good cable will not deviate much in its characteristics from the test cable used in calibration to those deployed in the field, allowing calibration to be performed once for a PHY-cable pair. To perform the calibration and estimate the cable reach of a link, follow the following procedure.
Set 1: {0m, 200m, 400m, 600m, 800m, 1km}
Parameter | Register Address | Comments |
---|---|---|
2p4V Metric1 | 0x088D | 3 MSB hexadecimal digits for metric 1 for 2p4V mode |
2p4V Metric2 | 0x088E | 3 MSB hexadecimal digits for metric 2 for 2p4V mode |
2p4V Metric3 | 0x088F | 3 MSB hexadecimal digits for metric 3 for 2p4V mode |
2p4V Metric4 | 0x0890 | 3 MSB hexadecimal digits for metric 4 for 2p4V mode |
2p4V Metric5 | 0x0891 | 3 MSB hexadecimal digits for metric 5 for 2p4V mode |
2p4V Metric6 | 0x0892 | 3 MSB hexadecimal digits for metric 6 for 2p4V mode |
1V Metric1 | 0x0898 | 3 MSB hexadecimal digits for metric 1 for 1p0V mode |
1V Metric2 | 0x0899 | 3 MSB hexadecimal digits for metric 2 for 1p0V mode |
1V Metric3 | 0x089a | 3 MSB hexadecimal digits for metric 3 for 1p0V mode |
1V Metric4 | 0x089b | 3 MSB hexadecimal digits for metric 4 for 1p0V mode |
1V Metric5 | 0x089c | 3 MSB hexadecimal digits for metric 5 for 1p0V mode |
1V Metric6 | 0x089d | 3 MSB hexadecimal digits for metric 6 for 1p0V mode |
Cable1 | 0x08E9 | Round(Cable1/8) and convert it to hexadecimal digits |
Cable2 | 0x08EA | Round(Cable2/8) and convert it to hexadecimal digits |
Cable3 | 0x08EB | Round(Cable3/8) and convert it to hexadecimal digits |
Cable4 | 0x08EC | Round(Cable4/8) and convert it to hexadecimal digits |
Cable5 | 0x08ED | Round(Cable5/8) and convert it to hexadecimal digits |
Cable6 | 0x08EE | Round(Cable6/8) and convert it to hexadecimal digits |
Register information is not retained over power cycles. ALCD calibration information should be included in an initialization routine to be available for cable length estimation after each power-up.
The longest cable length for calibration must be greater than actual cable used .
Procedure to generate ALCD metric:
//For each output operating mode utilized in an application, record ALCD <cable, metric pair>
1.0 Vpp operating ALCD metrics
//For each cable length segment in ALCD range, record the ALCD metric
begin
0001 //check that link is established in 0x0001[2]
0A9D //read register 0x0A9D and record bits [15:4] for
end
2.4 Vpp operating ALCD metrics
//For each cable length segment in ALCD range, record the ALCD metric
begin
0001 //check that link is established in 0x0001[2]
0A9D //read register 0x0A9D and record bits [15:4] for
end
Set ALCD calibration registers during initialization routine:
begin
//Set ALCD cable length segments
08E9 0000 //Cable length 1 is 0 meters
08EA 0019 //Cable length 2 is 200 meters ([200 meters / 8] -> converted to hex)
08EB 0032 //Cable length 3 is 400 meters ([400 meters / 8] -> converted to hex)
08EC 004B //Cable length 4 is 600 meters ([600 meters / 8] -> converted to hex)
08ED 0064 //Cable length 5 is 800 meters ([800 meters / 8] -> converted to hex)
08EE 007D //Cable length 6 is 1000 meters([1000 meters / 8] -> converted to hex)
//Set 1.0 Vpp ALCD metrics
0898 0046 //ALCD metric for 0 meters is 046
0899 0067 //ALCD metric for 200 meters is 067
089A 0088 //ALCD metric for 400 meters is 088
089B 0137 //ALCD metric for 600 meters is 137
089C 0178 //ALCD metric for 800 meters is 178
089D 0263 //ALCD metric for 1000 meters is 263
//Set 2.4 Vpp ALCD metrics
088D 0078 //ALCD metric for 0 meters is 078
088E 0096 //ALCD metric for 200 meters is 096
088F 0120 //ALCD metric for 400 meters is 120
0890 0174 //ALCD metric for 600 meters is 174
0891 0201 //ALCD metric for 800 meters is 201
0892 0310 //ALCD metric for 1000 meters is 310
end