Holtek BS83A04C Manual page 75

BS83A04C
4-Key Enhanced Touch I/O Flash MCU
TKST
Module 0
TKBUSY
TKRCOV
Touch Key Data
Memory Access
: Set Touch Key interrupt request flag
: Read 2N bytes from Touch Key Data Memory to TKM0ROH/TKM0ROL registers
: Write 2N bytes from TKM016DH/TKM016DL registers to Touch Key Data Memory
Touch Key Auto Scan Mode Timing Diagram – TSC=1
In the auto scan mode the key oscillator and reference oscillator will automatically be enabled when
the TKST bit is set from low to high and disabled automatically when the TKBUSY bit changes
from high to low. If the TSC bit is cleard to low, time slot 0~3 are active. When the TKST bit is
set from low to high in the auto scan mode, the internal capacitor value of the reference oscillator
for the selected key to be scanned in the time slot 0 will first be read from a specific location of
the dedicated touch key data memory and loaded into the corresponding TKM0ROH/TKM0ROL
registers. Then the 16-bit C/F counter value will be written into the corresponding location of the
time slot 3 scanned key in the touch key data memory. After this, the selected key will start to be
scanned in time slot 0. At the end of the time slot 0 key scan operation, the reference oscillator
internal capacitor value for the next selected key will be read from the touch key data memory and
loaded into the TKM0ROH/TKM0ROL registers. Then the 16-bit C/F counter value of the current
scanned key will be written into the corresponding touch key data memory. The whole auto scan
operation will sequentially be carried out in the above specific way from time slot 0 to time slot 3.
At the end of the time slot 3 key scan operation, the reference oscillator internal capacitor value for
the time slot 0 selected key will again be read from the touch key data memory and loaded into the
TKM0ROH/TKM0ROL registers. Then the 16-bit C/F counter value will be written into the relevant
location of the time slot 3 scanned key in the touch key data memory. After all selected keys are
scanned, the TKRCOV bit will be set high and the TKBUSY bit will be cleared to zero as well as
an auto scan mode operation is completed. If the TSC bit is set high, only time slot 0 is active, only
time slot 0 is active to execute the touch key related operations and time slot 1~3 are invalid.
Periodic Auto Scan Mode
In addition to those actions mentioned in the auto scan mode, the periodic auto scan mode
provides periodic auto scan and C/F counter upper/lower threshold comparison functions. When
the TKMOD1~TKMOD0 bits are set to 10 or 11, the periodic auto scan mode is selcted to scan
the module keys automatically and periodically. Note that this mode is generally used in the IDLE
mode, in order to monitor the touch key state and minimise power consumption.
Rev. 1.00
Key Auto Scan Cycle
Time slot 0
Clear to zero by software
75
Time slot 0
March 24, 2020