C8051F120 Datasheet, PDF (188/356 Pages) Silicon Laboratories – Mixed Signal ISP Flash MCU Family

C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Electrical specifications for the precision internal oscillator are given in Table 14.1. Note that the system
clock may be derived from the programmed internal oscillator divided by 1, 2, 4, or 8, as defined by the
IFCN bits in register OSCICN.
.
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
Variable
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x8B
SFR Page: F
Bits 7-0: OSCICL: Internal Oscillator Calibration Register.
This register calibrates the internal oscillator period. The reset value for OSCICL defines the
internal oscillator base frequency. The reset value is factory calibrated to generate an inter-
nal oscillator frequency of 24.5 MHz.
Figure 14.2. OSCICL: Internal Oscillator Calibration Register
R/W
R
R/W
R
R/W
R/W
R/W
R/W
Reset Value
IOSCEN IFRDY
-
-
-
-
IFCN1
IFCN0 11000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x8A
SFR Page: F
Bit 7: IOSCEN: Internal Oscillator Enable Bit.
0: Internal Oscillator Disabled.
1: Internal Oscillator Enabled.
Bit 6: IFRDY: Internal Oscillator Frequency Ready Flag.
0: Internal Oscillator not running at programmed frequency.
1: Internal Oscillator running at programmed frequency.
Bits 5-2: Reserved.
Bits 1-0: IFCN1-0: Internal Oscillator Frequency Control Bits.
00: Internal Oscillator is divided by 8.
01: Internal Oscillator is divided by 4.
10: Internal Oscillator is divided by 2.
11: Internal Oscillator is divided by 1.
Figure 14.3. OSCICN: Internal Oscillator Control Register
190
Rev. 1.3