em78p257 ELAN Microelectronics Corp, em78p257 Datasheet - Page 38

• Manufacturer Part Number: em78p257
• Description: 8-bit Microcontroller
• Manufacturer: ELAN Microelectronics Corp

This specification is subject to change without prior notice.
Address
2. /RESET Configure
3. The status of RST, T, and P of STATUS register
X: not used.
t: check Table 6
Refer to Fig.11 When the RESET bit in the OPTION word is programmed to 0, the external /RESET is enabled.
When programmed to 1, the internal /RESET is enabled, tied to the internal Vdd and the pin is defined as P71.
Voltage Detector
A RESET condition is initiated by one of the following events:
The values of RST, T, and P, as listed in Table 7 below. are used to check how the processor wakes up.
Table 8 shows the events which may affect the status of RST, T, and P.
Power-On Reset
Oscillator
ENWDTB
1. A power-on condition.
2. A high-low-high pulse on the /RESET pin, or
3. Watchdog timer time-out.
Name
/RESET
Wake-Up from Pin
Reset Type
U: unknown or don’t care.
Change
WDT
WDT Timeout
Fig. 11 Block Diagram of Reset of Controller
VDD
Bit 7
P
D
Bit 6
P
CLK
38
CLR
Q
Bit 5
P
P: previous value before reset.
Setup time
Bit 4
P
Bit 3
P
Bit 2
P
Reset
EM78P257
CLK
07.27.2004 (V1.4)
OTP ROM
Bit 1
P
Bit 0
P