1999 Jun 15

8

Philips Semiconductors

Product specification

Infrared remote control transmitter RC5

PCA8521

Table 3

ROM bit description

Pulse output

The bits of the remote control word, as indicated by the addressed ROM locations, are loaded into a shift register every

bit-time this register is shifted. The output is used to generate a logic 0 or a logic 1 in the biphase (Manchester) coding,

modulated with a frequency of 36 kHz. The duty factor of the modulation pulses may be selected (optionally) to be 25%

or 33.3%. The output of the pulse generator controls the output driver that can provide a maximum current of 45 mA.

BITS

FUNCTION

M0L to M5L

Command bits 0 to 5.

M6L

Field bit. This bit indicates whether command codes 0 to 63 are used (field bit is at logic 1) or

command codes 64 to 127 are used (field bit is at logic 0).

M7L

Inhibit bit. When this bit is at logic 1 no transmission will take place. When this bit is at logic 0

the appropriate code-word will be transmitted.

M0H to M4H

System bits 0 to 4.

M5H to M7H

Bank select. Will be stored in BS0 to BS2 when the ‘multi-system’ option is selected. With

single system bits M5H to M7H are don't care.

Fig.4 Timer schematic diagram.

handbook, full pagewidth

MBH035

432 kHz

or

4 MHz

OSCILLATOR

S

Q

CLK

R

Q

CLR

start input

no key

end control

CLK1

CLK2

INV

STOP

432 kHz

4 MHz

DIVIDE BY 111

DIVIDE BY 12

CONTROL

TIMER

DIVIDE-BY-4096

pulse

C0

C11