HT82K68 Holtek Semiconductor Inc, HT82K68 Datasheet - Page 16

• Manufacturer Part Number: HT82K68
• Description: Multimedia Keyboard Encoder OTP
• Manufacturer: Holtek Semiconductor Inc

To enable the counting operation, the timer
ON bit (TON; bit 4 of TMRC) should be set to 1.
In the case of timer counter OFF condition,
writing data to the timer counter preload reg-
ister will also reload that data to the timer
counter. But if the timer counter is turned on,
data written to it will only be kept in the
timer counter preload register. The timer coun-
ter will still operate until overflow occurs. When
the timer counter (reading TMR) is read, the
clock will be blocked to avoid errors. As clock
blocking may results in a counting error, this
must be taken into consideration by the program-
mer.
Label
TON
TM0
TM1
¾
¾
Bits
0~3
4
5
6
7
Unused bits, read as "0"
To enable/disable timer counting
(0= disabled; 1= enabled)
Unused bits, read as "0"
10= Timer mode (internal clock)
Preliminary
TMRC register
Timer counter
16
Input/output ports
There are 32 bidirectional input/output lines in
the HT82K68E, labeled from PA to PE, which
are mapped to the data memory of [12H], [14H],
[16H], [18H] and [1AH] respectively. All these
I/O ports can be used for input and output opera-
tions. 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, 16H, 18H or 1AH). For output op-
eration, all data is latched and remains un-
changed until the output latch is rewritten.
Function
HT82K68E
August 8, 2000