SC18IS602_602B_603_4

© NXP B.V. 2008. All rights reserved.

Product data sheet

Rev. 04 — 11 March 2008

6 of 25

NXP Semiconductors

SC18IS602/602B/603

the Function ID. There is no restriction on the number or combination of Slave Selects that

can be enabled for an SPI message. If more than one SSn pin is enabled at one time, the

user should be aware of possible contention on the data outputs of the SPI slave devices.

[1]

SS3 does not exist in the SC18IS603.

[2]

SS2 does not exist in the SC18IS602 and SC18IS603. Only SC18IS602B supports this function.

the slave address and Function ID. For example, if the message shown in Figure 7 is

will automatically send this same number of bytes to the SPI bus. As the data is

transmitted from the MOSI pin, it is also read from the MISO pin and saved in the data

buffer. Therefore, the old data in the buffer is overwritten. The data in the buffer can then

be read back.

be completed by reading the data buffer. Section 8 gives an example of an SPI read.

7.1.4 Read from buffer

A read from the data buffer requires no Function ID. The slave address with the R/W bit

master. The buffer contents are not modified during the read process.

A typical write and read from an SPI EEPROM is shown in Section 8.

Table 3.

Function ID 01h to 0Fh

7

6

5

4

3

2

1

0

0000

SS3[1]

SS2[2]

SS1

SS0

Fig 7.

Fig 8.

SPI message

A

S

002aac448

A

P

FUNCTION

ID

W

SLAVE ADDRESS

write to buffer

DATA 1

A

A

DATA n

A

002aac451

SPI data

DATA 1

DATA n

Fig 9.

Read from buffer

A

S

002aac449

P

R

SLAVE ADDRESS

DATA 1

A

A

DATA n

NA