Datasheet

 1997 Microchip Technology Inc. DS30444E - page 97

PIC16C9XX

13.2 LCD Interrupts

The LCD timing generation provides an interrupt that

deﬁnes the LCD frame timing. This interrupt can be

used to coordinate the writing of the pixel data with the

start of a new frame. Writing pixel data at the frame

boundary allows a visually crisp transition of the image.

This interrupt can also be used to synchronize external

events to the LCD. For example, the interface to an

external segment driver, such as a Microchip AY0438,

can be synchronized for segment data update to the

LCD frame.

A new frame is deﬁned to begin at the leading edge of

the COM0 common signal. The interrupt will be set

immediately after the LCD controller completes

accessing all pixel data required for a frame. This will

occur at a certain ﬁxed time before the frame boundary

as shown in Figure 13-9. The LCD controller will begin

to access data for the next frame within T

FWR after the

interrupt.

FIGURE 13-9: EXAMPLE WAVEFORMS IN 1/4 MUX DRIVE

COM0

COM1

COM2

COM3

Frame

Boundary

Frame

Boundary

1 Frame

LCD

Interrupt

occurs

Controller accesses

next frame data

TFINT

TFWR

TFWR = TFRAME/(LMUX1:LMUX0 + 1)

FINT = (TFWR /2 - (2TCY + 40 ns)) → min.

FWR /2 - (1TCY + 40 ns)) → max.