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EM78P221/2N
8-Bit Microcontroller with OTP ROM
Product Specification (V1.0) 10.19.2007 • 27
(This specification is subject to change without further notice)
The first two cases (1 & 2) will cause the EM78P221/2N to reset. The T and P flags of
R3 can be used to determine the source of the reset (wake-up). Cases 3 & 4 are
considered the continuation of program execution and the global interrupt ("ENI" or
"DISI" being executed) decides whether or not the controller branches to the interrupt
vector following a wake-up. If ENI is executed before SLEP, the instruction will begin to
execute from Address 0x8 after wake-up. If DISI is executed before SLEP, the
execution will restart from the instruction next to SLEP after wake-up. All sleep mode
wake up time is dependent on the oscillator mode, no matter what the oscillator type or
mode is (except when it’s in LXT2 mode). In LXT2 mode, wake-up time is 2 ~ 3 sec.
Only one of Cases 1 to 4 can be enabled before entering into sleep mode. That is:
Case [a] If WDT is enabled before SLEP, all of the RE bit is disabled. Hence, the
EM78P221/2N can be awakened only with Case 1 or Case 2. Refer to the
section on Interrupt (Section 6.6) for further details.
Case [b] If Port 6 Input Status Change is used to wake -up EM78P221/2N and ICWE
bit of Bank 0-RE register is enabled before SLEP, WDT must be disabled.
Hence, the EM78P221/2N can be awakened only with Case 3. Wake-up
time is dependent on the oscillator mode. In RC mode (VDD: 5V, IRC:
4MHz), wake-up time is 10 μs (for stable oscillators). In HXT2 mode (VDD:
5V, Crystal: 4MHz, C1/C2: 30pF), wake-up time is 800μs (for stable
oscillators), and in LXT2 mode, wake-up time is 2 ~ 3 sec.
Case [c] If the Comparator output status change is used to wake-up the EM78P221/ 2N
and the CMPWE bit of the RE register is enabled before SLEP, WDT must be
disabled by software. Hence, the EM78P221/2N can be awakened only with
Case 4.
Wake-up time is dependent on the oscillator mode. In RC mode (VDD: 5V,
IRC: 4MHz), wake-up time is 10μs (for stable oscillators). In HXT2 mode
(VDD: 5V, Crystal: 4MHz, C1/C2: 30 pF), wake-up time is 800μs (for stable
oscillators), and in LXT2 mode, wake-up time is 2 ~ 3 sec.