HT49RA1_14 Datasheet, PDF (14/57 Pages) Holtek Semiconductor Inc – Remote Type 8-Bit MCU with LCD

HT49RA1/HT49CA1
b7
b0
L V D O Q O S C L V D C R T 2 R T 1 R T 0 R e a l T im e C lo c k C o n tr o l R e g is te r
R T C In te r r u p t P e r io d
R T2 R T1 R T0
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
P e r io d
2 ⁸/fS
2 ⁹/fS
2 ¹⁰/fS
2 ¹¹/fS
2 ¹²/fS
2 ¹³/fS
2 ¹⁴/fS
2 ¹⁵/fS
L o w V o lta g e D e te c to r C o n tr o l
1 : e n a b le
0 : d is a b le
R T C O s c illa to r Q u ic k - s ta r t
1 : d is a b le
0 : e n a b le
L o w V o lta g e D e te c to r O u tp u t
1 : lo w v o lta g e d e te c te d
0 : n o r m a l v o lta g e
N o t im p le m e n te d , r e a d a s " 0 "
RTCC Register
RTCC register bits, time-out values from 2⁸/f_S to 2¹⁵/f_S
can be generated. The RTCC register also controls the
quick start up function of the RTC oscillator. This oscilla-
tor, which has a fixed frequency of 32768Hz, can be
made to start up at a quicker rate by setting bit 4, known
as the QOSC bit to ²0². This bit will be set to a ²0² value
when the device is powered on, however, as some extra
power is consumed, the QOSC bit should be set to ²1²
after about 2 seconds to reduce power consumption.
Interrupt Control Register - INTC0, INTC1
These 8-bit registers, known as INTC0 and INTC1, con-
trol the operation of both the external and internal inter-
rupts. By setting various bits within these registers using
standard bit manipulation instructions, the enable/dis-
able function of the external interrupts and each of the
internal interrupts can be independently controlled. A
master interrupt bit within these registers, the EMI bit,
acts like a global enable/disable and is used to set all of
the interrupt enable bits on or off. This bit is cleared
when an interrupt routine is entered to disable further in-
terrupt and is set by executing the ²RETI² instruction.
LCDC Register - LCDC
The LCDC register is used as the control register for the
LCD panel. The LCDEN bit is the overall on/off control
for the LCD driver and can be used to power down the
driver and thus used to conserve power when the LCD is
not used. As four segment lines are also pin-shared with
four Port PD lines, bits SEGPT0~SEGPT3 in the LCDC
register are used to determine which function is chosen,
either LCD segment line or normal I/O line. This register
also contains a bit to control the RTC on/off enable. The
RTC on/off control is however also dependent upon
which clock is chosen as the internal fs clock source.
The accompanying table shows the overall RTC control
operation.
LCDEN and RTCEN may decide LCD and RTC On/Off condition on normal operation.
f_S Clock
Source
f_SYS/4
WDT OSC
RTC OSC
(WDT enable)
RTC OSC
(WDT disable)
LCD/RTC Control Bits
LCDEN, RTCEN=0, 0 LCDEN, RTCEN=0, 1 LCDEN, RTCEN=1, 0 LCDEN, RTCEN=1, 1
LCD off, RTC off
LCD off, RTC off
LCD on, RTC off
LCD on, RTC off
LCD off, RTC off
LCD off, RTC off
LCD on, RTC off
LCD on, RTC off
LCD off, RTC on
LCD off, RTC on
LCD on, RTC on
LCD on, RTC on
LCD off, RTC off
LCD off, RTC on
LCD on, RTC on
LCD on, RTC on
Rev. 1.10
14
March 30, 2014