C8051F901-GU Silicon Laboratories Inc, C8051F901-GU Datasheet - Page 185

• Manufacturer Part Number: C8051F901-GU
• Description: IC MCU 8BIT 8KB FLASH 24QSOP
• Manufacturer: Silicon Laboratories Inc
• Series: C8051F9xxr

Specifications of C8051F901-GU

• Program Memory Type: FLASH
• Program Memory Size: 8KB (8K x 8)
• Package / Case: 24-QSOP
• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 25MHz
• Connectivity: SMBus (2-Wire/I²C), SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Number Of I /o: 16
• Ram Size: 768 x 8
• Voltage - Supply (vcc/vdd): 0.9 V ~ 3.6 V
• Data Converters: A/D 15x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Processor Series: C8051F9x
• Core: 8051
• Data Ram Size: 768 B
• Interface Type: UART
• Maximum Clock Frequency: 25 MHz
• Number Of Timers: 4
• Operating Supply Voltage: 0.9 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: C8051F912DK
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit
• Package: 24QSOP
• Device Core: 8051
• Family Name: C8051F90x
• Maximum Speed: 25 MHz
• Data Bus Width: 8 Bit
• Number Of Programmable I/os: 16
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-1847-5

19.4. Special Function Registers for Selecting and Configuring the System Clock
The clocking sources on C8051F91x-C8051F90x devices are enabled and configured using the OSCICN,
OSCICL, OSCXCN and the SmaRTClock internal registers. See Section “20. SmaRTClock (Real Time
Clock)” on page 188 for SmaRTClock register descriptions. The system clock source for the MCU can be
selected using the CLKSEL register. To minimize active mode current, the oneshot timer which sets Flash
read time should by bypassed when the system clock is greater than 10 MHz. See the FLSCL register
description for details.
The clock selected as the system clock can be divided by 1, 2, 4, 8, 16, 32, 64, or 128. When switching
between two clock divide values, the transition may take up to 128 cycles of the undivided clock source.
The CLKRDY flag can be polled to determine when the new clock divide value has been applied. The clock
divider must be set to "divide by 1" when entering Suspend or Sleep Mode.
The system clock source may also be switched on-the-fly. The switchover takes effect after one clock
period of the slower oscillator.
SFR Definition 19.1. CLKSEL: Clock Select
SFR Page = All Pages; SFR Address = 0xA9
Name
Reset
Type
6:4
2:0
Bit
Bit
7
3
CLKRDY
CLKSEL[2:0] System Clock Select.
CLKDIV[2:0]
CLKRDY
Unused
R
Name
7
0
R/W
System Clock Divider Clock Ready Flag.
0: The selected clock divide setting has not been applied to the system clock.
1: The selected clock divide setting has been applied to the system clock.
System Clock Divider Bits.
Selects the clock division to be applied to the undivided system clock source.
000: System clock is divided by 1.
001: System clock is divided by 2.
010: System clock is divided by 4.
011: System clock is divided by 8.
100: System clock is divided by 16.
101: System clock is divided by 32.
110: System clock is divided by 64.
111: System clock is divided by 128.
Unused.
Read = 0b. Must Write 0b.
Selects the oscillator to be used as the undivided system clock source.
000: Precision Internal Oscillator.
001: External Oscillator.
011: SmaRTClock Oscillator.
100: Low Power Oscillator.
All other values reserved.
6
0
CLKDIV[2:0]
R/W
5
1
R/W
Rev. 1.0
4
1
C8051F91x-C8051F90x
R/W
Function
3
0
R/W
2
1
CLKSEL[2:0]
R/W
1
0
R/W
0
0
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