C8051F961-A-GM Silicon Labs, C8051F961-A-GM Datasheet - Page 291

• Manufacturer Part Number: C8051F961-A-GM
• Description: 8-bit Microcontrollers - MCU 128KB, DC-DC, LCD AES, QFN40
• Manufacturer: Silicon Labs

Specifications of C8051F961-A-GM

• Rohs: yes
• Core: 8051
• Processor Series: C8051
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 25 MHz
• Program Memory Size: 128 KB
• Data Ram Size: 8448 B
• On-chip Adc: Yes
• Operating Supply Voltage: 2.5 V to 3.3 V
• Operating Temperature Range: - 40 C to + 85 C
• Package / Case: QFN-40
• Mounting Style: SMD/SMT
• Number Of Programmable I/os: 34
• Number Of Timers: 4

23.4. Special Function Registers for Selecting and Configuring the System Clock
The clocking sources on C8051F96x devices are enabled and configured using the OSCICN, OSCICL,
OSCXCN and the SmaRTClock internal registers. See Section “24. SmaRTClock (Real Time Clock)” on
page 295 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 23.1. CLKSEL: Clock Select
SFR Page = 0x0 and 0xF; 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
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.
Read = 0b. Must Write 0b.
Selects the oscillator to be used as the undivided system clock source.
000: Precision Internal Oscillator.
001: External Oscillator.
010: Low Power Oscillator divided by 8.
011: SmaRTClock Oscillator.
100: Low Power Oscillator.
All other values reserved.
6
0
CLKDIV[2:0]
R/W
5
0
Rev. 0.5
4
1
R/W
Function
3
0
2
0
CLKSEL[2:0]
C8051F96x
R/W
1
1
0
0
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