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Chapter 50 Subclock Calibration Unit
5.Register Description
5.2 32 kHz / 100 kHz Timer Data Register (16 bit) (CUTD)
The 32kHz/100kHz Timer Data Register (CUTD) holds the value which determines the duration of calibration
(32kHz/100kHz reload value)
Default value is 0x8000 which corresponds to a measurement duration of 1 second, if a 32.768
kHz crystal is used.
This register should be written only when the calibration is inactive (STRT=0).
The 32kHz/100kHz Timer Register stores the value to specify the duration of the calibration.
When the calibration is started, the stored value is loaded into the 32kHz/100kHz Timer and the
timer starts counting down until it reaches zero.
If CUTD is initialized with 0000 an underflow will occur and the measurement will take (FFFF hex
+ 1) * T
osc32/osc100
The 32kHz/100kHz timer operates with the 32kHz or with the 100kHz oscillation clock (see
chapter “4.4 CSCFG: Clock Source Configuration Register (Page No.196)” how to select
between those clocks.
In order to achieve a measurement duration of 1 second at a 32kHz oscillation, the CUTD register
has to be load with 0x8000 = 32768 dec. This number results from the exact oscillation frequency
of the crystal, which is F
osc
=32768 Hz. The ideal values of the measurement results (if a 4.00
MHz crystal is used) are shown in the following table.
In order to achieve a measurement duration of half a second at a 100kHz oscillation, the CUTD
register has to be load with 0xC350 = 50000 dec. This number results from the exact oscillation
frequency of the crystal, which is F
osc
=100000 Hz. The ideal values of the measurement results
(if a 4.00 MHz crystal is used) are shown in the following table.
TDD15TDD14 TDD13TDD12 TDD11TDD10
TDD9 TDD8
⇐ Bit no.
Read/write ⇒
(R/W) (R/W) (R/W) (R/W) (R/W) (R/W) (R/W) (R/W)
Default value⇒
(1) (0) (0) (0) (0) (0) (0) (0)
32/100kHz Timer Register high byte
Address : 0004B2
H
15 14 13 12 11 10 9 8
CUTDH
TDD7 TDD6 TDD5 TDD4 TDD3 TDD2 TDD1 TDD0
⇐ Bit no.
Read/write ⇒
(R/W) (R/W) (R/W) (R/W) (R/W) (R/W) (R/W) (R/W)
Default value⇒
(0) (0) (0) (0) (0) (0) (0) (0)
Address : 0004B3
H
765432 10
CUTDL
32/100kHz Timer
Register low byte