EM78P156EL
OTP ROM
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).
CLK(=Fosc/2 or Fosc/4)
0
TCC
Pin
1
TE
0
WDT
1
WTE
(in IOCE)
M
U
X
TS
M
U
X
PAB
1
M
U
X
0
PAB
Data Bus
SYNC
2 cycles
TCC (R1)
TCC overflow interrupt
8-bit Counter
8-to-1 MUX
0
1
MUX
WDT time-out
M
U
X
PAB
PSR0~PSR2
IOCA
Initial
value
PAB
4.4 I/O Ports
Fig. 5 Block Diagram of TCC and WDT
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 R-option mode, the current/power
consumption by Rex should be taken into the consideration to promote energy conservation.
The I/O registers and I/O control registers are both readable and writable. The I/O interface circuits for
Port 5 and Port 6 are shown in the following Figures 6, 7(a), 7(b), 7(C)and Figure 8.
1 <Note>: Vdd = 5V, set up time period = 16.8ms ± 30%
Vdd = 3V, set up time period = 18ms ± 30%
This specification is subject to change without prior notice.
16
07.29.2004 (V1.3)