C8051F320 Silicon Laboratories Inc, C8051F320 Datasheet - Page 123

• Manufacturer Part Number: C8051F320
• Description: IC 8051 MCU 16K FLASH 32LQFP
• Manufacturer: Silicon Laboratories Inc
• Series: C8051F32xr

Specifications of C8051F320

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 25MHz
• Connectivity: SMBus (2-Wire/I²C), SPI, UART/USART, USB
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Number Of I /o: 25
• Program Memory Size: 16KB (16K x 8)
• Program Memory Type: FLASH
• Ram Size: 2.25K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 3.6 V
• Data Converters: A/D 17x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-LQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -

13.3. 4x Clock Multiplier
The 4x Clock Multiplier allows a 12 MHz oscillator to generate the 48 MHz clock required for Full Speed USB com-
munication (see
put can also be used as the system clock. See
selection.
The 4x Clock Multiplier is configured via the CLKMUL register. The procedure for configuring and enabling the 4x
Clock Multiplier is as follows:
Important Note: When using an external oscillator as the input to the 4x Clock Multiplier, the external source
must be enabled and stable before the Multiplier is initialized. See
nal oscillator source.
Bit7:
Bit6:
Bit5:
Bits4-2:
Bits1-0:
MULEN
R/W
Bit7
1.
2.
3.
4.
5.
6.
Reset the Multiplier by writing 0x00 to register CLKMUL.
Select the Multiplier input source via the MULSEL bits.
Enable the Multiplier with the MULEN bit (CLKMUL | = 0x80).
Delay for >5 µs.
Initialize the Multiplier with the MULINIT bit (CLKMUL | = 0xC0).
Poll for MULRDY => ‘1’.
MULEN: Clock Multiplier Enable
0: Clock Multiplier disabled.
1: Clock Multiplier enabled.
MULINIT: Clock Multiplier Initialize
This bit should be a ‘0’ when the Clock Multiplier is enabled. Once enabled, writing a ‘1’ to this bit
will initialize the Clock Multiplier. The MULRDY bit reads ‘1’ when the Clock Multiplier is stabi-
lized.
MULRDY: Clock Multiplier Ready
This read-only bit indicates the status of the Clock Multiplier.
0: Clock Multiplier not ready.
1: Clock Multiplier ready (locked).
Unused. Read = 000b; Write = don’t care.
MULSEL: Clock Multiplier Input Select
These bits select the clock supplied to the Clock Multiplier.
MULINIT MULRDY
Section “15.4. USB Clock Configuration” on page
R/W
Bit6
Figure 13.5. CLKMUL: Clock Multiplier Control Register
MULSEL
00
01
10
11
Bit5
R
R/W
Bit4
-
External Oscillator / 2
Section 13.4
External Oscillator
Internal Oscillator
Selected Clock
RESERVED
R/W
Bit3
-
Rev. 1.1
for details on system clock and USB clock source
R/W
Bit2
Section 13.4
-
150). A divided version of the Multiplier out-
R/W
Bit1
for details on selecting an exter-
MULSEL
C8051F320/1
R/W
Bit0
SFR Address
00000000
Reset Value
0xB9
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