ht82m9be Holtek Semiconductor Inc., ht82m9be Datasheet - Page 16

• Manufacturer Part Number: ht82m9be
• Description: Ht82m99e/ht82m99a -- Usb Mouse Encoder 8-bit Mcu
• Manufacturer: Holtek Semiconductor Inc.

also depends on the control register. If the control regis-
ter bit is 1 , the input will read the pad state. If the con-
trol register bit is 0 , the contents of the latches will
move to the internal bus. The latter is possible in the
CMOS/NMOS/PMOS configurations can be selected
(NMOS and PMOS are available for PA only). These
control registers are mapped to locations 13H 15H and
17H.
After a chip reset, these input/output lines remain at high
levels or in a floating state (depending on the
pull-high/low options). Each bit of these input/output
latches can be set or cleared by SET [m].i and CLR
[m].i (m=12H, 14H or 16H) instructions.
Some instructions first input data and then follow the
output operations. For example, SET [m].i , CLR
[m].i , CPL [m] , CPLA [m] read the entire port states
into the CPU, execute the defined operations
(bit-operation), and then write the results back to the
latches or the accumulator.
Each line of PA0~PA7, PB4 and PB7 has the capability
of waking-up the device.
There are pull-high/low options available for I/O lines.
Once the pull-high/low option of an I/O line is selected,
the I/O line have pull-high/low resistor. Otherwise, the
pull-high/low resistor is absent. It should be noted that a
non-pull-high/low I/O line operating in input mode will
cause a floating state.
It is recommended that unused or not bonded out I/O
lines should be set as output pins by software instruction
to avoid consuming power under input floating state.
Note: *1: To make sure that the system oscillator has stabilized, the SST provides an extra delay of 1024 system
Rev. 1.60
read-modify-write instruction. For output function,
*2: A low voltage has to exist for more than 1ms, after that 1ms delay, the device enters a reset mode.
clock pulses before entering the normal operation.
Low Voltage Reset
16
Low Voltage Reset - LVR
The microcontroller contains a low voltage reset circuit
in order to monitor the supply voltage of the device. If the
supply voltage of the device drops to within the range of
0.9V~V
tery, the LVR will automatically reset the device inter-
nally.
The LVR includes the following specifications:
The relationship between V
Note: V
For a valid LVR signal, a low voltage (0.9V~V
exist for more than 1ms. If the low voltage state does
not exceed 1ms, the LVR will ignore it and will not per-
form a reset function.
The LVR uses the OR function with the external
RES signal to perform a chip reset.
tion at 6MHz or 12MHz system clock.
LVR
OPR
such as might occur when changing the bat-
is the voltage range for proper chip opera-
HT82M9BE/HT82M9BA
DD
and V
LVR
is shown below.
April 16, 2008
LVR
) must