SAA5288 查看數據表（PDF） - Philips Electronics

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SAA5288

TV microcontroller with full screen On Screen Display (OSD)

Philips Electronics 

Philips Semiconductors

TV microcontroller with full screen

On Screen Display (OSD)

Preliminary specification

SAA5288

7.3.5 6-BIT PWM DACS

Eight 6-bit DACs are available to allow direct control of analogue sections of the television.

Each low resolution 6-bit DAC is controlled by its associated Special Function Register (PWM0 to PWM7). The PWM

outputs are alternative functions of Port 2 and P3.4. The PWE bit in the SFR for the port corresponding to the PWM

should be set to logic 1 for correct operation of the PWM, e.g. if PWM0 is to be used, P2.1 should be set to logic 1 setting

the port pin to high-impedance.

7.3.5.1 Pulse Width Modulator Registers (PWM0 to PWM7)

Table 3 Pulse Width Modulator Registers (see Table 10 for addresses)

7

6

PWE

−

5

4

3

2

1

0

PV5

PV4

PV3

PV2

PV1

PV0

Table 4 Description of PWMn bits (n = 0 to 7)

BIT

SYMBOL

DESCRIPTION

7

PWE If PWE is set to a logic 1, the corresponding PWM is active and controls its assigned

port pin. If PWE is set to la logic 0, the port pin is controlled by the corresponding bit in

the port SFR.

6

−

not used

5

PV5

The output of the PWM is a pulse of period 21.33 µs with a pulse HIGH time determined

4

PV4

by the binary value of these 6-bits multiplied by 0.33 µs. PV5 is the most significant bit.

3

PV3

2

PV2

1

PV1

0

PV0

1997 Jun 24

9

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