IBM EM78P259N/260N manual 16 IOC91 Low Time Register, IOCA1 High Time Register

EM78P259N/260N

8-Bit Microprocessor with OTP ROM

6.2.16 IOC91 (Low Time Register)

The 8-bit Low time register controls the active or Low segment of the pulse.

The decimal value of its contents determines the number of oscillator cycles and verifies that the IR OUT pin is active. The active period of IR OUT can be calculated as follows:

NOTE

■Low time width = { [1+decimal low time value (IOC91)] * Low 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 Low time down counter underflow (if enabled), the next instruction will be fetched from Address 015H (Low time).

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 determine 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 (if enabled), the next instruction will be fetched from Address 012H (High time).

6.2.18 IOCB1 High/Low Time Scale Control Register)

Bit 7	Bit 6	Bit 5	Bit 4	Bit 3	Bit 2	Bit 1	Bit 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.

Product Specification (V1.2) 05.18.2007 • 25

(This specification is subject to change without further notice)