C8051F327-GM Silicon Laboratories Inc, C8051F327-GM Datasheet - Page 94

• 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

C8051F326/7
12.4. USB Clock Configuration
USB0 is capable of communication as a Full or Low Speed USB function. Communication speed is
selected via the SPEED bit in SFR USB0XCN. When operating as a Low Speed function, the USB0 clock
must be 6 MHz. When operating as a Full Speed function, the USB0 clock must be 48 MHz. Clock options
are described in Section “10. Oscillators” on page 71. The USB0 clock is selected via SFR CLKSEL (see
Figure 10.5 on Page 77). The USB transceiver must be enabled before enabling Clock Recovery.
Clock Recovery circuitry uses the incoming USB data stream to adjust the internal oscillator; this allows
the internal oscillator (and 4x Clock Multiplier) to meet the requirements for USB clock tolerance. Clock
Recovery should be used in the following configurations:
When operating USB0 as a Low Speed function with Clock Recovery, software must write ‘1’ to the
CRLOW bit to enable Low Speed Clock Recovery. Clock Recovery is typically not necessary in Low Speed
mode.
Single Step Mode can be used to help the Clock Recovery circuitry to lock when high noise levels are pres-
ent on the USB network. This mode is not required (or recommended) in typical USB environments.
94
Bit7:
Bit6:
Bit5:
Bits4–0: Reserved. Read = Variable. Must Write = 01001b.
CRE
R/W
Bit7
Communication Speed
USB Register Definition 12.5. CLKREC: Clock Recovery Control
CRE: Clock Recovery Enable.
This bit enables/disables the USB clock recovery feature.
0: Clock recovery disabled.
1: Clock recovery enabled.
CRSSEN: Clock Recovery Single Step.
This bit forces the oscillator calibration into ‘single-step’ mode during clock recovery.
0: Normal calibration mode.
1: Single step mode.
CRLOW: Low Speed Clock Recovery Mode.
This bit must be set to ‘1’ if clock recovery is used when operating as a Low Speed USB
device.
0: Full Speed Mode.
1: Low Speed Mode.
CRSSEN
R/W
Low Speed
Bit6
Full Speed
CRLOW
R/W
Bit5
R/W
Bit4
Internal Oscillator/2
4x Clock Multiplier
USB Clock
Rev. 1.1
R/W
Bit3
Reserved
R/W
Bit2
4x Clock Multiplier Input
R/W
Internal Oscillator
Bit1
N/A
R/W
Bit0
USB Address:
00001001
Reset Value
0x0F