M66271FP

REJ03F0267-0200 Rev.2.00 Mar 18, 2008

Page 13 of 27

Function of Cycle Steal Control

M66271FP has a function for processing data of a line with more efficient. This function access with the cycle steal

method as taking

WAIT for MPU during the display term with necessity for the display data transfer from built-in

VRAM to LCD.

On other side, don't output

WAIT for keeping throughput of MPU during the horizontal synchronous term with no

necessity for the display data transfer from VRAM to LCD side.

But certainly set a term of accessing with the cycle steal method by CSW register, for controlling an error action near

the end of horizontal synchronous term.

Ex.) Assuming 320

× 240 dots LCD

LP

CP

UD <3:0>

CSE

(Internal signal)

Setting by CR register

Displaying term (Cycle steal method)

(Necessity for data transfer from VRAM to LCD side)

Horizontal synchronous term

(No necessity for data transfer from VRAM to LCD side)

Setting by LPW register

Start WAIT for MPU according to

cycle steal access

Access with bus timing of MPU

without

WAIT for MPU.

Start WAIT for MPU in timing of CSE "H"

according to bus timing of MPU

4-bit transfer

Output every transfer of

a display data

Output when finish transfer

of display data with a line

1 Line

1

1

2

3

78

79

80

Setting by CSW register

Figure 4 Function of Cycle Steal Control

Handling of Oscillator Pin

Crystal oscillator

C1

Rf

C2

Rd

OSC2

OSC1

Open

OSC2

OSC1

Clock

generator

Note: As far as possible, connect C, R and the crystal oscillator at near the pin.

<1> Crystal oscillator

<2> Input from external clock directly

M66271FP

M66271FP

Figure 5 Oscillator Pin