em78p131a ELAN Microelectronics Corp, em78p131a Datasheet - Page 22

• Manufacturer Part Number: em78p131a
• Description: 8-bit Microcontroller With Otp Rom
• Manufacturer: ELAN Microelectronics Corp

EM78P131A
8-Bit Microcontroller with OTP ROM
18 •
following a wake-up. If ENI is executed before SLEP, the instruction will begin to
execute from Address 008H after a wake-up. If DISI is executed before SLEP, the
operation will restart from the succeeding instruction right next to SLEP after a
wake-up.
Only one of Cases 2 and 3 can be enabled before going into Sleep mode. That is,
[a] if Port 6 Input Status Change Interrupt is enabled before SLEP, WDT must be
[b] if WDT is enabled before SLEP, Port 6 Input Status Change Interrupt must be
If Port 6 Input Status Change Interrupt is used to wake-up the EM78P131A (Case [a]
above), the following instructions must be executed before SLEP:
MOV A, @xxxx1110b
CONTW
WDTC
MOV A, @0xxxxxxxb
IOW RE
MOV R6, R6
MOV A, @00000x1xb
IOW RF
ENI (or DISI)
SLEP
disabled by software. However, the WDT bit in the option register remains enabled.
Hence, the EM78P131A can be awakened only by Case 1 or Case 3.
disabled. Hence, the EM78P131A can be awakened only by Case 1 or Case 2.
Refer to Section 5.6, Interrupt for further details.
1. After waking up from sleep mode, WDT is automatically enabled. The WDT
2. To avoid a reset from occurring when the Port 6 Input Status Changed Interrupt
enable/disable operation after waking up from sleep mode should be appropriately
defined in the software.
enters into an interrupt vector or is used to wake-up the MCU, the WDT prescaler
must be set above 1:1 ratio.
; Enable (or disable) global interrupt
; Select the WDT prescaler, it must be
; Clear WDT and prescaler
; Disable WDT
; Read Port 6
; Enable Port 6 input change interrupt
; Sleep
; set over 1:1
(This specification is subject to change without further notice)
NOTE
Product Specification (V1.2) 09.16.2009