
EM78P221/2N
8-Bit Microcontroller with OTP ROM
8
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Product Specification (V1.0) 10.19.2007
(This specification is subject to change without further notice)
6.2 Registers Description
6.2.1 A
(Accumulator)
Internal data transfer operation, or instruction operand holding usually involves the
temporary storage function of the Accumulator. The Accumulator is not an
addressable register.
6.2.2 CONT (Control Register)
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
INTE INT TS
TE PSTE PST2 PST1 PST0
Bit 7 (INTE):
INT signal edge
0
= interrupt occurs at the rising edge on the INT0 and INT1 pin
1
= interrupt occurs at the falling edge on the INT0 and INT1 pin
Bit 6 (INT):
Interrupt enable flag
0
= masked by DISI or hardware interrupt
1
= enabled by the ENI/RETI instructions
This bit is readable only.
Bit 5 (TS):
TCC signal source
0
= internal instruction cycle clock. If P56 is used as I/O pin, TS must be 0.
1
= transition on the TCC pin
Bit 4 (TE):
TCC signal edge
0
= increment if the transition from low to high takes place on the TCC pin
1
= increment if the transition from high to low takes place on the TCC pin.
Bit 3 (PSTE):
Prescaler enable bit for TCC
0
= prescaler disable bit. TCC rate is 1:1
1
= prescaler enable bit. TCC rate is set as Bit 2 ~ Bit 0.
Bit 2 ~ Bit 0 (PST2 ~ PST0)
: TCC prescaler bits
PST2
PST1
PST0
TCC Rate
0 0 0 1:2
0 0 1 1:4
0 1 0 1:8
0 1 1
1:16
1 0 0
1:32
1 0 1
1:64
1 1 0
1:128
1 1 1
1:256
Note:
Tcc time-out period [1/Fosc x prescaler x (256 -Tcc cnt) x 1]
Fosc: Oscillator (Crystal, ERC, IRC) frequency