C8051F327-GM Silicon Laboratories Inc, C8051F327-GM Datasheet - Page 75

• Manufacturer Part Number: C8051F327-GM
• Description: IC 8051 MCU FLASH 16K 28QFN
• Manufacturer: Silicon Laboratories Inc
• Series: C8051F32xr

Specifications of C8051F327-GM

• Program Memory Type: FLASH
• Program Memory Size: 16KB (16K x 8)
• Package / Case: 28-QFN
• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 25MHz
• Connectivity: UART/USART, USB
• Peripherals: POR
• Number Of I /o: 15
• Ram Size: 1.5K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 3.6 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Processor Series: C8051F3x
• Core: 8051
• Data Bus Width: 8 bit
• Data Ram Size: 1.5 KB
• Interface Type: UART/USB
• Maximum Clock Frequency: 25 MHz
• Number Of Programmable I/os: 15
• Number Of Timers: 2
• Operating Supply Voltage: 2.7 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: PK51, CA51, A51, ULINK2
• Development Tools By Supplier: C8051F326DK
• Minimum Operating Temperature: - 40 C
• Package: 28QFN EP
• Device Core: 8051
• Family Name: C8051F327
• Maximum Speed: 25 MHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: 336-1481 - DAUGHTER CARD TOOLSTCK C8051F327770-1006 - ISP 4PORT FOR SILABS C8051F MCU
• Eeprom Size: -
• Data Converters: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-1297-5

10.4. 4x Clock Multiplier
The 4x Clock Multiplier allows a 12 MHz oscillator to generate the 48 MHz clock required for Full Speed
USB communication (see Section “12.4. USB Clock Configuration” on page 94). A divided version of the
Multiplier output can also be used as the system clock. See Section “10.5. System and USB Clock Selec-
tion” on page 76 for details on system clock and USB clock source 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 clock as the input to the 4x Clock Multiplier, the external source
must be stable before the Multiplier is initialized. See Section “10.5. System and USB Clock Selection” on
page 76 for details on clock selection.
Bit7:
Bit6:
Bit5:
Bits4–1: Unused. Read = 0000b. Write = don’t care.
Bit0:
MULEN
R/W
Bit7
1. Reset the Multiplier by writing 0x00 to register CLKMUL.
2. Select the Multiplier input source via the MULSEL bits.
3. Enable the Multiplier with the MULEN bit (CLKMUL | = 0x80).
4. Delay for >5 µs.
5. Initialize the Multiplier with the MULINIT bit (CLKMUL | = 0xC0).
6. 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 stabilized.
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).
MULSEL: Clock Multiplier Input Select
This bit selects the clock supplied to the Clock Multiplier.
MULINIT MULRDY
R/W
Bit6
SFR Definition 10.4. CLKMUL: Clock Multiplier Control
MULSEL
0
1
Bit5
R
R/W
Bit4
—
Internal Oscillator
Selected Clock
External Clock
Rev. 1.1
R/W
Bit3
—
R/W
Bit2
—
R/W
Bit1
—
C8051F326/7
MULSEL 00000000
R/W
Bit0
SFR Address
Reset Value
0xB9
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