TS87C54X2-LCA データシートの表示（PDF） - Atmel Corporation

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TS87C54X2-LCA

8-bit CMOS Microcontroller 16/32 Kbytes ROM/OTP

Atmel Corporation 

TS80C54X2/C58X2

TS87C54X2/C58X2

6.4.3 Given Address

Each device has an individual address that is specified in SADDR register; the SADEN register is a mask byte

that contains don’t-care bits (defined by zeros) to form the device’s given address. The don’t-care bits provide the

flexibility to address one or more slaves at a time. The following example illustrates how a given address is formed.

To address a device by its individual address, the SADEN mask byte must be 1111 1111b.

For example:

SADDR

SADEN

Given

0101 0110b

1111 1100b

0101 01XXb

The following is an example of how to use given addresses to address different slaves:

Slave A:

SADDR

SADEN

Given

1111 0001b

1111 1010b

1111 0X0Xb

Slave B:

SADDR

SADEN

Given

1111 0011b

1111 1001b

1111 0XX1b

Slave C:

SADDR

SADEN

Given

1111 0010b

1111 1101b

1111 00X1b

The SADEN byte is selected so that each slave may be addressed separately.

For slave A, bit 0 (the LSB) is a don’t-care bit; for slaves B and C, bit 0 is a 1. To communicate with slave A

only, the master must send an address where bit 0 is clear (e.g. 1111 0000b).

For slave A, bit 1 is a 1; for slaves B and C, bit 1 is a don’t care bit. To communicate with slaves B and C, but

not slave A, the master must send an address with bits 0 and 1 both set (e.g. 1111 0011b).

To communicate with slaves A, B and C, the master must send an address with bit 0 set, bit 1 clear, and bit 2

clear (e.g. 1111 0001b).

6.4.4 Broadcast Address

A broadcast address is formed from the logical OR of the SADDR and SADEN registers with zeros defined as

don’t-care bits, e.g.:

SADDR

0101 0110b

SADEN

1111 1100b

Broadcast =SADDR OR SADEN 1111 111Xb

The use of don’t-care bits provides flexibility in defining the broadcast address, however in most applications, a

broadcast address is FFh. The following is an example of using broadcast addresses:

Slave A:

SADDR

1111 0001b

SADEN

1111 1010b

Broadcast 1111 1X11b,

Slave B:

SADDR

1111 0011b

SADEN

1111 1001b

Broadcast 1111 1X11B,

Slave C:

SADDR=

1111 0010b

SADEN

1111 1101b

Broadcast 1111 1111b

For slaves A and B, bit 2 is a don’t care bit; for slave C, bit 2 is set. To communicate with all of the slaves, the

master must send an address FFh. To communicate with slaves A and B, but not slave C, the master can send

and address FBh.

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Rev. C - 15 January, 2001

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