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Rev. 1.20
60
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Rev. 1.20
61
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HT69F30A/HT69F40A/HT69F50A
TinyPower
TM
I/O Flash 8-Bit MCU with LCD & EEPROM
HT69F30A/HT69F40A/HT69F50A
TinyPower
TM
I/O Flash 8-Bit MCU with LCD & EEPROM
Fast Wake-up
To minimise power consumption the device can enter the SLEEP or IDLE0 Mode, where the system
clock source to the device will be stopped. However when the device is woken up again, it can take
a considerable time for the original system oscillator to restart, stabilize and allow normal operation
to resume. To ensure the device is up and running as fast as possible a Fast Wake-up function is
provided, which allows f
SUB
, namely the LIRC oscillator, to act as a temporary clock to first drive the
system until the original system oscillator has stabilised. As the clock source for the Fast Wake-up
function is f
SUB
, the Fast Wake-up function is only available in the SLEEP1 and IDLE0 modes.
When the device is woken up from the SLEEP0 mode, the FastWake-up function has no effect
because the f
SUB
clock is stopped. The FastWake-up enable/disable function is controlled using the
FSTEN bit in the SMOD register.
If the HXT oscillator is selected as the NORMAL Mode system clock and if the Fast Wake-up
function is enabled, then it will take one to two t
SUB
clock cycles of the LIRC oscillator for the
system to wake-up. The system will then initially run under the f
SUB
clock source until 1024 HXT
clock cycles have elapsed, at which point the HTO flag will switch high and the system will switch
over to operating from the HXT oscillator.
If the ERC/HIRC or EC/LIRC oscillator is used as the system oscillator, then it will take15~16 clock
cycles of the ERC/HIRC oscillator or 1~2 clock cycles of the LIRC osrillator respectively to wake
up the system from the SLEEP or IDLE0 Mode. The Fast Wake-up bit, FSTEN will have no effect
in these cases.
System
Oscillator
FSTEN
Bit
Wake-up Time
(SLEEP0 Mode)
Wake-up Time
(SLEEP1 Mode)
Wake-up Time
(IDLE0 Mode)
Wake-up Time
(IDLE1 Mode)
HXT
0
1024 HXT �y�les
1024 HXT �y�les
1~2 HXT �y�les
1
1024 HXT �y�les
1~2 f
SUB
�y�les
(System �uns with f
SUB
first for 1024 HXT
�y�les and then swit�hes ove� to �un with
the HXT �lo�k )
1~2 HXT �y�les
ERC
x
1�~16 ERC �y�les
1�~16 ERC �y�les
1~2 ERC �y�les
HIRC
x
1�~16 HIRC �y�les
1�~16 HIRC �y�les
1~2 HIRC �y�les
EC
x
1~2 EC �y�les
1~2 EC �y�les
1~2 EC �y�les
LIRC
x
1~2 LIRC �y�les
1~2 LIRC �y�les
1~2 LIRC �y�les
LXT
x
1024 LXT �y�les
1024 LXT �y�les
1~2 LXT �y�les
Wake-up Times
Note that if the Watchdog Timer is disabled, which means that the f
SUB
clock drived from the LXT
or LIRC oscillator is off, then there will be no Fast Wake-up function available when the device
wakes-up from the SLEEP0 Mode.
Operating Mode Switching
The device can switch between operating modes dynamically allowing the user to select the best
performance/power ratio for the present task in hand. In this way microcontroller operations that
do not require high performance can be executed using slower clocks thus requiring less operating
current and prolonging battery life in portable applications.
In simple terms, Mode Switching between the NORMAL Mode and SLOW Mode is executed
using the HLCLK bit and CKS2~CKS0 bits in the SMOD register while Mode Switching from the
NORMAL/SLOW Modes to the SLEEP/IDLE Modes is executed via the HALT instruction. When
a HALT instruction is executed, whether the device enters the IDLE Mode or the SLEEP Mode is
determined by the condition of the IDLEN bit in the SMOD register and FSYSON in the SMOD1
register.