BS2824 Holtek Semiconductor Inc., BS2824 Datasheet - Page 32

• Manufacturer Part Number: BS2824
• Description: Touch Key Mcu
• Manufacturer: Holtek Semiconductor Inc.

BS2824/BS2854/BS2868
Touch Key MCU
Rev. 1.00
Mode Switching
Touch Key Circuits Power Down
Operating Mode Control
The devices are switched between one mode and another using a combination of the CLKMOD bit
in the CTRL0 register and the HALT instruction. The CLKMOD bit chooses whether the system
runs in either the Normal or Slow Mode by selecting the system clock to be sourced from either a
high or low frequency oscillator. The HALT instruction forces the system into either the Idle or
Sleep Mode, depending upon whether the LXT oscillator is running or not. The HALT instruction
operates independently of the CLKMOD bit condition.
When a HALT instruction is executed and the LXT oscillator is not running, the system enters the
Sleep mode the following conditions exist:
Although the microcontroller is powered down using the HALT instruction the Touch Key Circuits
are powered down and enter the standby state in an independent way and are not influenced by the
HALT instruction or the microcontroller operation mode. Basically if no touch action is encountered
on the touch key inputs for a certain period of time then the touch key circuits will enter a standby
state. Details are provided in the Touch Key Functional Description section.
BS2824, BS2854
BS2868
The system oscillator will stop running and the application program will stop at the HALT
instruction.
The Data Memory contents and registers will maintain their present condition.
The WDT will be cleared and resume counting if the WDT clock source is selected to come from
the WDT or LXT oscillator. The WDT will stop if its clock source originates from the system
clock.
The I/O ports will maintain their present condition.
In the status register, the Power Down flag, PDF, will be set and the Watchdog time-out flag, TO,
will be cleared.
Normal
Slow
Sleep
Normal
Slow
Idle
Sleep
Operating
Operating
Mode
Mode
Stop
Stop
Stop
Stop
HXT
HXT
Run
Run
Configuration
OSC1/OSC2
ERC
ERC
Stop
Stop
Stop
Stop
Run
Run
32
OSC1/OSC2 Configuration
HIRC
HIRC
Stop
Stop
Stop
Stop
Run
Run
XT1/XT2 Configuration
LXTEN=0
HIRC
Stop
Stop
Stop
Stop
Run
Run
Run
HIRC + LXT
LXT
unimplemented
LXTEN=1
Stop
LXT
Run
Run
Run
Run
Run
Run
January 27, 2010