BS67F340 Datasheet, PDF (233/281 Pages) Holtek Semiconductor Inc – Enhanced Touch A/D Flash MCU with LCD Driver

BS67F340/BS67F350/BS67F360/BS67F370
Enhanced Touch A/D Flash MCU with LCD Driver
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. When the TKST bit is set from low to high in the auto scan mode, the first reference
oscillator internal capacitor value will be read from a specific location of the dedicated touch key
data memory and loaded into the corresponding TKMnROH/TKMnROL registers. Then the 16-bit
C/F counter value will be written into the last location of the corresponding touch key module data
memory. After this the selected key will 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 the next TKMnROH/TKMnROL 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. After four keys are scanned, the TKRCOV bit will be
set high and the TKBUSY bit will be set low. At the end of the auto scan mode, the first reference
oscillator internal capacitor value will again be read from the touch key data memory and loaded
into the corresponding TKMnROH/TKMnROL registers. Then the 16-bit C/F counter value will
again be written into the relevant touch key data memory.
Touch Key Data Memory
Each of the devices provides two dedicated Data Memory area for the touch key auto scan mode.
One area is used to store the 16-bit C/F counter values of the touch key module 0~n and located
in Data Memory Sector 5. The other area is used to store the reference oscillator internal capacitor
values of the touch key module 0~n and located in Data Memory Sector 6.
Rev. 1.40
233
December 15, 2016