EM78156E
8-Bit Microcontroller with MASK ROM
internal clock, TCC will increase by 1 at every instruction cycle (without prescaler).
Referring to Fig. 5, CLK=Fosc/2 or CLK=Fosc/4 application is determined by the
CODE Option bit CLK status. CLK=Fosc/2 is used if CLK bit is "0", and
CLK=Fosc/4 is used if CLK bit is "1". If TCC signal source comes from external
clock input, TCC is increased by 1 at every falling edge or rising edge of TCC pin.
ꢀ
The watchdog timer is a free running on-chip RC oscillator. The WDT will keep on
running even when the oscillator driver has been turned off (i.e. in sleep mode).
During normal operation or sleep mode, a WDT time-out (if enabled) will cause the
device to reset. The WDT can be enabled or disabled any time during normal
mode by software programming. Refer to WDTE bit of IOCE register. Without
prescaler, the WDT time-out period is approximately 18 ms1 (default).
Data Bus
CLK(=Fosc/2 or Fosc/4)
0
1
0
TCC
Pin
M
U
X
M
U
X
SYNC
2 cycles
TCC (R1)
1
TE
TCC overflow interrupt
TS
PAB
0
1
M
U
X
8-bit Counter
M
U
X
IOCA
WDT
WTE
PAB
PAB
(in IOCE)
8-to-1 MUX
Initial
value
PSR0~PSR2
0
1
MUX
WDT time-out
PAB
Fig. 5 Block Diagram of TCC and WDT
4.4 I/O Ports
The I/O registers, both Port 5 and Port 6, are bi-directional tri-state I/O ports. Port 6 can
be pulled high internally by software. In addition, Port 6 can also have open-drain
output by software. Input status change interrupt (or wake-up) function on Port 6. P50
~ P52 and P60 ~ P63 pins can be pulled down by software. Each I/O pin can be
defined as "input" or "output" pin by the I/O control register (IOC5 ~ IOC6). P50~P51
are the R-option pins enabled by setting the ROC bit in the IOCE register to 1. When
the R-option function is used, it is recommended that P50~P51 are used as output pins.
When R-option is in enable state, P50~P51 must be programmed as input pins. Under
1 <Note>: Vdd = 5V, set up time period = 16.8ms ± 30%
Vdd = 3V, set up time period = 18ms ± 30%
12 •
Product Specification (V1.3) 07.29.2004
(This specification is subject to change without further notice)
ELAN [ ELAN MICROELECTRONICS CORP ]
