Chapter 11
RTC Time Base Timer (RTC-TBT)
Control Register XI - 7
11.2.3 RTC-TBT Frequency Adjustment Register
The frequency of T1HZ to T128HZ can be adjusted with the TBTADJL and the TBTADJH.
The following table shows the frequency adjustment rate of T1HZ.
Adjustment value = 128 [sec] × Frequency adjustment rate × 2097152 / Adjustment period [sec] (in decimal)
= Frequency adjustment rate × 0x200000 (in hexadecimal) (At Adjustment period = 128 [sec])
Table:11.2.2 lists the setting value of TBTADJ10-0 and frequency adjustment rate.
Table:11.2.2 Frequency Adjustment Rate (Adjustment period = 128 sec)
TBTADJ10-0
Hexadecimal
Frequency
adjustment rate
(ppm)
109876543210
01111111111 0x3FF + 487.80
01111111110 0x3FE + 487.33
01111111101 0x3FD + 486.85
::::::::::: : :
00000000100 0x004 + 1.91
00000000011 0x003 + 1.43
00000000010 0x002 + 0.95
00000000001 0x001 + 0.48
00000000000 0x000 0
11111111111 0x7FF - 0.48
11111111110 0x7FE - 0.95
11111111101 0x7FD - 1.43
11111111100 0x7FC - 1.91
11111111011 0x7FB - 2.38
11111111010 0x7FA - 2.86
11111111001 0x7F9 - 3.34
::::::::::: : :
10000000010 0x402 - 487.33
10000000001 0x401 - 487.80
10000000000 0x400 - 488.28
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