Rev. 1.71
118
April 11, 2017
Rev. 1.71
119
April 11, 2017
HT66F002/HT66F0025/HT66F003/HT66F004
Cost-Effective A/D Flash MCU with EEPROM
HT66F002/HT66F0025/HT66F003/HT66F004
Cost-Effective A/D Flash MCU with EEPROM
Every interrupt has the capability of waking up the microcontroller when it is in SLEEP or IDLE
Mode, the wake up being generated when the interrupt request flag changes from low to high. If it is
required to prevent a certain interrupt from waking up the microcontroller then its respective request
flag should be first set high before enter SLEEP or IDLE Mode.
As only the Program Counter is pushed onto the stack, then when the interrupt is serviced, if the
contents of the accumulator, status register or other registers are altered by the interrupt service
program, their contents should be saved to the memory at the beginning of the interrupt service
routine.
To return from an interrupt subroutine, either a RET or RETI instruction may be executed. The RETI
instruction in addition to executing a return to the main program also automatically sets the EMI
bit high to allow further interrupts. The RET instruction however only executes a return to the main
program leaving the EMI bit in its present zero state and therefore disabling the execution of further
interrupts.
SCOM Function for LCD – HT66F004
The HT66F004 device has the capability of driving external LCD panels. The common pins for
LCD driving, SCOM0~SCOM3, are pin shared with certain pin on the I/O ports. The LCD signals
are generated using the application program.
LCD peration
An external LCD panel can be driven using this device by configuring the I/O pins as common pins.
The LCD driver function is controlled using the SCOMC register which in addition to controlling
the overall on/off function also controls the bias voltage setup function. This enables the LCD COM
driver to generate the necessary V
DD
/2 voltage levels for LCD 1/2 bias operation.
The SCOMEN bit in the SCOMC register is the overall master control for the LCD driver. The
LCD SCOMn pin is selected to be used for LCD driving by the corresponding pin-shared function
selection bits. Note that the Port Control register does not need to first setup the pins as outputs to
enable the LCD driver operation.
LCD COM Bias