HT45R06 Holtek Semiconductor, HT45R06 Datasheet - Page 15

• Manufacturer Part Number: HT45R06
• Description: A/D Type 8-Bit OTP MCU
• Manufacturer: Holtek Semiconductor

In the case of timer/event counter OFF condition, writing
data to the timer/event counter preload register will also
reload that data to the timer/event counter. But if the
timer/event counter is turned on, data written to it will
only be kept in the timer/event counter preload register.
The timer/event counter will still operate until overflow
occurs. When the timer/event counter (reading TMR) is
read, the clock will be blocked to avoid errors. As clock
blocking may result in a counting error, this must be
taken into consideration by the programmer.
The bits 0~2 of the TMRC can be used to define the
pre-scaling stages of the internal clock sources of the
timer/event counter. The definitions are as shown. The
overflow signal of the timer/event counter can be used
to generate PFD signals for buzzer driving.
Input/Output Ports
There are 13 bidirectional input/output lines in the
microcontroller, labeled from PA, PB and PD, which are
mapped to the data memory of [12H], [14H] and [18H]
respectively. All of these I/O ports can be used for input
Rev. 1.00
Timer/Event Counter
Input/Output Ports
15
and output operations. For input operation, these ports
are non-latching, that is, the inputs must be ready at the
T2 rising edge of instruction MOV A,[m] (m=12H, 14H
or 18H). For output operation, all the data is latched and
remains unchanged until the output latch is rewritten.
Each I/O line has its own control register (PAC, PBC,
PDC) to control the input/output configuration. With this
control register, CMOS output or Schmitt trigger input
with or without pull-high resistor structures can be re-
configured dynamically under software control. To func-
tion as an input, the corresponding latch of the control
register must write 1 . The input source also depends
on the control register. If the control register bit is 1 ,
the input will read the pad state. If the control register bit
is 0 , the contents of the latches will move to the inter-
nal bus. The latter is possible in the read-modify-write
instruction.
For output function, CMOS is the only configuration.
These control registers are mapped to locations 13H,
15H and 19H.
HT45R06
May 24, 2005