EM78P5841N 데이터 시트보기 (PDF) - ELAN Microelectronics
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EM78P5841N Datasheet PDF : 68 Pages
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EM78P5840N/41N/42N
8-Bit Microcontrollers
7.2.11 RA (PLL, Main Clock Selection, Watchdog Timer, DT2H)
Page 0 (PLL Enable Bit, Main Clock Selection Bits, Watchdog Timer Enable Bit)
Bit 7
0
R/W-0
Bit 6
PLLEN
R/W-0
Bit 5
CLK2
R/W-0
Bit 4
CLK1
R/W-0
Bit 3
CLK0
R/W-0
Bit 2
-
-
Bit 1
-
-
Bit 0
WDTEN
R/W-0
Bit 0 (WDTEN): Watchdog control bit
"0" : Disable watchdog
"1" : Enable watchdog
The WDTC instruction can be used to clear the watchdog counter. The
watchdog counter is a free-running on-chip RC oscillator. The WDT will
keep on running even after the oscillator driver has been turned off (i.e.,
in Sleep mode). During normal operation or Sleep mode, a WDT
time-out (if enabled) will cause the device to reset. The WDT can be
enabled or disabled any time during Green mode or Normal mode.
Without the presacler, the WDT time-out period is approximately 18 ms.
Bit 1 ~ Bit 2 (undefined): These bits are not used
Bit 3 ~ Bit 5 (CLK0 ~ CLK2): Main clock selection bits in Crystal mode. These three
bits are NOT used in IRC and ERIC mode.
In Crystal Mode:
Different frequencies for the main clock can be chosen with the CLK0,
CLK1 and CLK2 bits. All available clock selections are listed below:
PLLEN CLK2 CLK1 CLK0 Sub Clock Main Clock
CPU Clock
1
0
0
0
32.768kHz 3.582MHz 3.582MHz (Normal mode
1
0
0
1
32.768kHz 3.582MHz 3.582MHz (Normal mode
1
0
1
0
32.768kHz 3.582MHz 3.582MHz (Normal mode
1
0
1
1
32.768kHz 3.582MHz 3.582MHz (Normal mode
1
1
0
0
32.768kHz 14.3MHz 14.3MHz (Normal mode)
1
1
0
1
32.768kHz 14.3MHz 14.3MHz (Normal mode)
1
1
1
0
32.768kHz 14.3MHz 14.3MHz (Normal mode)
1
1
1
1
32.768kHz 14.3MHz 14.3MHz (Normal mode)
0 don’t care don’t care don’t care 32.768kHz don’t care 32.768kHz (Green mode
Bit 6 (PLLEN): PLL's power control bit is the CPU mode control register. This bit is
only used under Crystal mode. Under RC mode, this bit will be
ignored.
"0" : Disable PLL
"1" : Enable PLL
14 •
Product Specification (V1.0) 04.25.2006
(This specification is subject to change without further notice)
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