C8051F530-TB Silicon Laboratories Inc, C8051F530-TB Datasheet - Page 142

• Manufacturer Part Number: C8051F530-TB
• Description: BOARD PROTOTYPE W/C8051F530
• Manufacturer: Silicon Laboratories Inc
• Type: MCUr

Specifications of C8051F530-TB

• Contents: Board
• Processor To Be Evaluated: C8051F52xA and C8051F53xA
• Interface Type: USB
• Lead Free Status / RoHS Status: Vendor undefined / Vendor undefined
• For Use With/related Products: C8051F530
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

C8051F52x/F52xA/F53x/F53xA
14.3. System Clock Selection
The internal oscillator requires little start-up time and may be selected as the system clock immediately fol-
lowing the OSCICN write that enables the internal oscillator. External crystals and ceramic resonators typ-
ically require a start-up time before they are settled and ready for use. The Crystal Valid Flag (XTLVLD in
register OSCXCN) is set to 1 by hardware when the external oscillator is settled. To avoid reading a false
XTLVLD in crystal mode, the software should delay at least 1 ms between enabling the external
oscillator and checking XTLVLD. RC and C modes typically require no startup time.
The CLKSL bit in register CLKSEL selects which oscillator source is used as the system clock. CLKSL
must be set to 1 for the system clock to run from the external oscillator; however the external oscillator may
still clock certain peripherals (timers, PCA) when another oscillator is selected as the system clock. The
system clock may be switched on-the-fly between the internal oscillator and external oscillator, as long as
the selected clock source is enabled and has settled.
SFR Definition 14.5. CLKSEL: Clock Select
142
Bits7–6: Unused. Read = 00b; Write = don’t care.
Bits5–4: Reserved. Read = 00b; Must write 00b.
Bit3:
Bits2–1: Reserved. Read = 00b; Must write 00b.
Bit0:
Bit7
R
-
Unused. Read = 0b; Write = don’t care.
CLKSL: System Clock Select
0: Internal Oscillator (as determined by the IFCN bits in register OSCICN).
1: External Oscillator.
Bit6
R
-
Reserved Reserved
R/W
Bit5
R/W
Bit4
Rev. 1.3
Bit3
R
-
Reserved Reserved
R/W
Bit2
R/W
Bit1
SFR Address:
CLKSL
R/W
Bit0
00000000
Reset Value
0xA9