eorex
Base Timer
(Preliminary)
EU1010 / EU1011
Base timer is optioned from [BASE1, BASE0] and it will cause a period timer base interrupt enabled
(TBINT=1) & (TBEN=1). But the real time counter have the same clock source and it is optioned by
UCCLK.7($03H.7=CKSEL).
BASE1
0
0
1
1
BASE0
0
1
0
1
T
BASE
T
T
/2
T
T
/4
T
T
/8
T
T
/16
MCU clock selection
With a built-in internal RC oscillator, the MCU frequency is 4MHz
±3%
@4.5V. MCU system clock
offers 4MHz, 2MHz, 1MHz, 512KHz or 256KHz by MCU clock options bit; RCSEL2~0. Please refer to
the following table.
Address
Name
03H
UCCLK
bit7
#
#
0
bit6
bit5
bit4
RTC1
W
0
bit3
bit2
bit1
bit0
BASE1 BASE0
W
0
W
0
RTC0 RCSEL2 RCSEL1 RCSEL0
W
0
W
0
W
0
W
0
Read or Write
Default Value
The MCU system clock could be switched by setting RCSEL2~0. First, pre-set RCSEL2~0 register and
then execute “HALT” instruction. After then, MCU wake-up from HALT mode, MCU system frequency is
already changed to the new setting frequency.
RCSEL2
0
0
0
0
1
RCSEL1
0
0
1
1
#
RCSEL0
0
1
0
1
#
Frequency of MCU system clock
256KHz
512KHz
1MHz
2MHz
4MHz
Aug.2007
7/21
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