AT32F425
Series Reference Manual
2022.03.30
Page 421
Ver 2.01
21.6
Register description
Refer to the list of abbreviations used in register descriptions.
These peripheral registers must be accessed by words (32 bits).
21.6.1 ACC register map
Table 21-2 ACC register map and reset values
Register name
Offset
Reset value
ACC_STS
0x00
0x0000 000
ACC_CTRL1
0x04
0x0000 0100
ACC_CTRL2
0x08
0x0000 2080
ACC_C1
0x0C
0x0000 1F2C
ACC_C2
0x10
0x0000 1F40
ACC_C3
0x14
0x00000 1F54
21.6.2 Status register (ACC_STS)
Bit
Register
Reset value
Type
Description
Bit 31: 9
Reserved
0x0000000
resd
Kept at its default value.
Bit 1
RSLOST
0x0
ro
Reference Signal Lost
0: Reference Signal is not lost
1: Reference Signal is lost
Note: During the calibration, when the sample counter of
the calibration module is twice that of C2, if a SOF
reference signal is not detected, it means that the
reference signal is lost. The internal statue machine will
move to the idle state unless another SOF signal is
detected, otherwise, the interal clock sample counter
remains 0. The RSLOST bit is immediately cleared after
the CALON bit is cleared or when the RSLOST is written
with 0. Reference signal detection occurs only when
CALON=1.
Bit 0
CALRDY
0x0
ro
Internal high-speed clock calibration ready
0: Interal 8MHz oscillator calibration is not ready
1: Interal 8MHz oscillator calibration is ready
Note: This bit is set by hardware to indicate that internal
8MHz oscillator has been calibrated to the frequency
closest to 8MHz. The CALRDY is immediately cleared
after the CALON bit is cleared or when the CALRDY is
written with 0.
21.6.3 Control register 1 (ACC_CTRL1)
Bit
Register
Reset value
Type
Description
Bit 31: 12 Reserved
0x00000
resd
Forced to 0 by hardware.
Bit 11: 8
STEP
0x1
rw
Calibrated step
This field defines the value after each calibration.
Note: It is recommended to set the step bit in order to get
a more accurate calibration result. While ENTRIM=0, only
the HICKCAL is calibrated. If the step is incremented or
decremented by one, the HICKCAL will be incremented or
decremented by one accordingly, and the HICK frequency
will increase or decrease by 40KHz (design value). This is
a positive relationship.
While ENTRIM=1, only the HICKTRIM is calibrated. If the
step is incremented or decremented by one, the
HICKTRIM will be incremented or decremented by one
accordingly, and the HICK frequency will increase or
decrease by 20KHz (design value). This is a positive
relationship.