BS85B12-3 Datasheet, PDF (116/182 Pages) Holtek Semiconductor Inc – Touch Key Flash Type 8-Bit MCU with LCD/LED Driver

BS85B12-3/BS85C20-3
Touch Key Flash MCU with LCD/LED Driver
Touch Key Interrupt
Each touch key module, which consists of four touch keys, has two independent interrupts, one for
each of the, 16-bit C/F counter and time slot counter.
The time slot counter interrupt has its own interrupt vector while the 16-bit C/F counter interrupts are
contained within the Multi-function interrupts and therefore do not have their own vector. Care must
be taken during programming as the 16-bit C/F counter interrupt flags contained within the
Multi-function interrupts will not be automatically reset upon entry into the interrupt service routine
but rather must be reset manually by the application program. More details regarding the touch key
interrupts are located in the interrupt section of the datasheet.
Programming Considerations
After the relevant registers are setup, the touch key detection process is initiated the changing the
MnST bit from low to high. This will enable and synchronise all relevant oscillators. The MnRCOV
flag, which is the time slot counter flag will go high and remain high until the counter overflows. When
this happens an interrupt signal will be generated.
When the external touch key size and layout are defined, their related capacitances will then determine
the sensor oscillator frequency.
Rev. 1.00
110
February 1, 2011