EM78P258N
8-Bit Microprocessor with OTP ROM
6.2.17 IOCA1 (High Time Register)
The 8-bit High-time register controls the inactive or High period of the pulse.
The decimal value of its contents determines the number of oscillator cycles and
verifies that the IR OUT pin is inactive. The inactive period of IR OUT can be calculated
as follows:
NOTE
■ High time width = {[1+decimal high-time value (IOCA1)] * High time Scale(IOCB1) } / FT
■ FT is system clock: FT=Fosc/1(CLK=2)
FT=Fosc/2(CLK=4)
When an interrupt is generated by the High time down counter underflow (when
enabled), the next instruction will be fetched from address 012H (High time).
6.2.18 IOCB1 High/Low Time Scale Control Register)
7
6
5
4
3
2
1
0
HTSE
HTS2
HTS1
HTS0
LTSE
LTS2
LTS1
LTS0
Bit 7 (HTSE):
High-time scale enable bit.
0 = scale disable bit, High-time rate is 1:1
1 = scale enable bit, High-time rate is set as Bit 6~Bit 4.
Bit 6 ~ Bit 4 (HTS2 ~ HTS0): High-time scale bits:
HTS2
HTS1
HTS0
High-Time Rate
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
1:2
1:4
1:8
1:16
1:32
1:64
1:128
1:256
Bit 3 (LTSE):
Low-time scale enable bit.
0 = scale disable bit, Low-time rate is 1:1
1 = scale enable bit, Low-time rate is set as Bit 2~Bit 0.
Bit 2 ~ Bit 0 (LTS2 ~ LTS0): Low-time scale bits:
LTS2
LTS1
LTS0
Low-Time Rate
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
1:2
1:4
1:8
1:16
1:32
1:64
1:128
1:256
24 •
Product Specification (V1.0) 06.16.2005
(This specification is subject to change without further notice)
ELAN [ ELAN MICROELECTRONICS CORP ]
