Chapter 1 Hardware Structure
External Timer Clock Input
Each device in the LCD Type MCUseries contains either one, two or three timers depending upon
which one is chosen. Each timer has an external input pin, which in the case of devices with a sin-
gle timer, is known as TMR. In the case of devices with two timers, their external timer input pins
are known as TMR0 and TMR1. For the HT49RU80/HT49CU80 devices, which contain three tim-
ers, their external timer pins are known as TMR0, TMR1 and TMR2. For all devices with a single
timer, the external input pin TMR is pin-shared with input pin PB2. For devices with two timers, the
external input pins TMR0 and TMR1 are pin-shared with input pins PB2 and PB3 respectively. For
the HT49RU80/HT49CU80 devices, their three timer pins are pin-shared with pins PB2, PB3 and
PB4. For these pin-shared pins to function as timer inputs, the corresponding control bits in the
timer control register must be correctly set. These external timer input pins can be used as normal
data input pins for applications that do not require external timer inputs. For such applications, the
timer mode control bits in the timer control register must select the timer mode, which has an inter-
nal clock source, to prevent the input pin from interfering with the timer operation.
UART Pins
The HT49RU80/HT49CU80 devices contain an internal Universal Asynchronous Receiver/Trans-
mitter UART function, which requires two external pins for their serial connection to external de-
vices. These pins known as TX and RX are pin-shared with I/O pins PC0 and PC1 respectively.
COM/SEG Outputs
The COM and SEG pins are used to directly drive the common and segment pins on the LCD. How-
ever, each device also has a pin which can be setup as either a segment or common driver, which
depending upon which device is chosen, are known as COM3/SEG18, COM3/SEG32, COM3/
SEG40 and COM3/SEG47. The chosen common or segment function of these pins is determined
by the duty configuration option. If the 1/4 duty configuration option is chosen, then the pin will be
setup as a COM3 driver. If the 1/2 or 1/3 duty configuration option is chosen, then the corresponding
SEG function will be selected. In the HT49RU80/HT49CU80 devices, a configuration option exists
to permit Port D to be used as either SEG outputs or standard CMOS data outputs.
V
D D
D a ta B it
D a ta B u s
D
C K
S
Q
Q
P u ll- H ig h O p tio n
C M O S /N M O S
O p tio n
W e a k
P u ll- u p
W r ite D a ta R e g is te r
C h ip R e s e t
P F D ( P A 3 o n ly )
B Z ( P A 1 o n ly )
B Z ( P A 0 o n ly )
M
U
P A 0 /B Z
P A 1 /B Z
P A 2
P A 3 /P F D
X
P F D o r B Z O p tio n
R e a d D a ta R e g is te r
S y s te m
W a k e -u p
W a k e - u p O p tio n
PA0~PA3 Input/Output Ports
45
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