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Table Of Contents

RTL8822CE RTL8822CU RTL8822CS COB TSSI MP FLOW

3.1.4. Crystal calibration

Start to Find Index

Set Index =

InitIndex

Set MCS7 40M Tx

Measure Carrier

Frequency (Hz)

Abs. Value of

MeasuredCFOffset < 2ppm

Have Found Index

Set Index = Index + (TargetCFOffset – MeasuredCFOsset) / Step

YES

Figure 6: Finding Crystal Cap. Index Flow

InitIndex: the default value is 0x40. Index range is 0x0 to 0x7F.

MeasuredCFOffset: Carrier frequency measured by instrument - ideal carrier frequency

target range Abs. Value of 2ppm in 2.4GHz band is about 10KHz(±5KHz).

TargetCFOffset: generally is 0 ppm.

Step: The value will be different from modules dominated by external capacitor beside the crystal,

so it must be able to modify simply in the initial file of test program. By experience, the value

variation is about +2 ~ +3KHz. The value should be checked by hardware RD and be filled in the

setup file of test program. The plus symbol means that the crystal Cap. index and carrier

frequency is positive-dependent (The larger index is relative to major carrier frequency).