PCF8584 datasheet(6/40 Pages) PHILIPS

6 / 40 page

1997 Oct 21

Philips Semiconductors

Product speciﬁcation

I2C-bus controller

PCF8584

FUNCTIONAL DESCRIPTION

6.1

General

The PCF8584 acts as an interface device between

standard high-speed parallel buses and the serial I2C-bus.

On the I2C-bus, it can act either as master or slave.

Bidirectional data transfer between the I2C-bus and the

parallel-bus microcontroller is carried out on a byte-wise

basis, using either an interrupt or polled handshake.

Interface to either 80XX-type (e.g. 8048, 8051, Z80) or

68000-type buses is possible. Selection of bus type is

automatically performed (see Section 6.2).

Fig.2 Pin configuration.

handbook, halfpage

CLK

SDA or SDA OUT

SCL or SCL IN

DB0

DB1

DB2

VSS

VDD

DB7

DB6

DB5

DB4

DB3

PCF8584

MLA012 - 1

IACK or SDA IN

INT or SCL OUT

RESET / STROBE

RD (DTACK)

WR (R/W)

(1)

(1) Pin mnemonics between parenthesis indicate the 68000 mode

pin designations.

Table 1

Control signals utilized by the PCF8584 for

microcontroller/microprocessor interfacing

The structure of the PCF8584 is similar to that of the

I2C-bus interface section of the Philips’

MABXXXX/PCF84(C)XX-series of microcontrollers, but

with a modified control structure. The PCF8584 has five

internal register locations. Three of these (own address

used for initialization of the PCF8584. Normally they are

only written once directly after resetting of the PCF8584.

The remaining two registers function as double registers

(data buffer/shift register S0, and control/status

transmission/reception. By using these double registers,

which are separately write and read accessible, overhead

for register access is reduced. Register S0 is a

combination of a shift register and data buffer.

the I2C-bus.

for bus access and/or monitoring.

6.2

Interface Mode Control (IMC)

Selection of either an 80XX mode or 68000 mode

interface is achieved by detection of the first WR-CS signal

sequence. The concept takes advantage of the fact that

the write control input is common for both types of

interfaces. An 80XX-type interface is default. If a

HIGH-to-LOW transition of WR (R/W) is detected while CS

is HIGH, the 68000-type interface mode is selected and

the DTACK output is enabled. Care must be taken that WR

and CS are stable after reset.

TYPE

R/W

DTACK

IACK

8048/

8051

yes

68000

yes

Z80

yes

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