em78f644nso28s ELAN Microelectronics Corp, em78f644nso28s Datasheet - Page 105

• Manufacturer Part Number: em78f644nso28s
• Description: Flash Series 8-bit Microcontroller
• Manufacturer: ELAN Microelectronics Corp

1
Product Specification (V1.0) 05.05.2010
(This specification is subject to change without further notice)
VDD=5V, WDT time-out period = 16.5ms ± 8%, VDD=3V, WDT time-out period = 18ms ± 8%.
TCC Pin
WDTE
TE
WDT
Fosc
The watchdog timer is a free running on-chip RC oscillator. The WDT will keep on
running even after the oscillator driver has been turned off (i.e., in Sleep mode).
During the normal operation or the Sleep mode, a WDT time-out (if enabled) will
cause the device to reset. The WDT can be enabled or disabled at any time during
the Normal mode by software programming. Refer to WDDTE bit of Bank0 R11
register (Section 6.3.14). Without prescaler, the WDT time-out period is
approximately 18 ms
6.5 I/O Ports
6.5.1 I/O for EM78F644N/642/641/544/542/541N
The I/O registers, Ports 5, 6, 7, and 8, are bidirectional tri-state I/O ports. Port 6 or 7
can be pulled high internally by software. Moreover, Port 6 can also have an open-
drain output by software. Input status change interrupt (or wake-up) function on Port
6 P50~P53, P60 ~ P63, and Port 7 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 ~ IOC8).
The I/O registers and I/O control registers are both readable and writable.
0
1
MUX
WDT time out
8 Bit Counter
TS
8 to 1 MUX
Figure 6-11 TCC and WDT Block Diagram
1
(one oscillator start-up timer period).
EM78F648/644/642/641/548/544/542/541N
8 Bit Counter
PST2~PST0
8 to 1 MUX
Prescaler
PSW2~PSW0
Prescaler
2 cycles
SYNC
8-Bit Microcontroller
TCC overflow
TCCDATA
Data Bus
interrupt
• 95