84C44X datasheet(18/38 Pages) PHILIPS

18 / 38 page

October 1994

Philips Semiconductors

Product speciﬁcation

8-bit microcontrollers with OSD and VST

84C44X; 84C64X; 84C84X

12 ON SCREEN DISPLAY

12.1

Features

• Display format: 2 rows × 16 characters

• Software controlled vertical and horizontal display

position

• 64 different (mask programmable) characters in ROM

• Black box background

• Four programmable display character sizes

• Four programmable character dot matrix sizes:

– 6

× 9 and 6 × 13

– 8

× 9 and 8 × 13

• Half-dot rounding for the whole screen

• 4 from 7 colours possible on screen

• Clock generator for on screen display function with:

– RC oscillator

– LC oscillator,

for the various types of PCA84C44X; 84C64X; 84C84X.

12.2

Horizontal display position control

The horizontal position counter is incremented every OSD

cycle after the programmed level of HSYNCN occurs at the

HSYNCN pin. The counter is reset when the opposite

polarity of the HSYNCN pulse is reached.

12.3

Vertical display position control

The vertical position counter is incremented every

HSYNCN cycle and is reset by the VSYNCN signal.

12.4

Clock generator

There are two types of oscillators available for the various

types. The oscillator is triggered on the trailing edge of

HSYNCN when the OSD logic is enabled and stops on the

following leading edge of HSYNCN.

The OSD oscillator must be externally adjusted to the

desired frequency (decreasing the OSD frequency gives

broader characters). Before the oscillation frequency can

be adjusted HSYNCN must be HIGH (if HLVL = 1).

Oscillation stops by setting the HSYNCN pin LOW when

HLVL = 1.

12.4.1

RC OSCILLATOR

The RC oscillator is available in the types:

PCA84C440; 84C443; 84C640; 84C643;

84C840; 84C843.

The external RC network is connected between

pin 28 and VSS (see Fig.19).

12.4.2

LC OSCILLATOR

The LC oscillator is available in the types:

PCA84C441; 84C444; 84C641; 84C644;

84C841; 84C844.

The external LC network is connected between

pins 28 and 29 (see Fig.20).

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