SC18IS602B

All information provided in this document is subject to legal disclaimers.

© NXP B.V. 2010. All rights reserved.

Product data sheet

Rev. 5 — 3 August 2010

13 of 25

NXP Semiconductors

SC18IS602B

7.2 SPI interface

The SPI interface can support Mode 0 through Mode 3 of the SPI specification and can

operate up to 1.8 Mbit/s. The SPI interface uses at least four pins: SPICLK, MOSI, MISO,

and Slave Select (SSn).

SSn are the slave select pins. In a typical configuration, an SPI master selects one SPI

device as the current slave.

There are actually four SSn pins (SS0, SS1, SS2 and SS3) to allow the SC18IS602B to

communicate with multiple SPI devices.

The SC18IS602B generates the SPICLK (SPI clock) signal in order to send and receive

data. The SCLK, MOSI, and MISO are typically tied together between two or more SPI

devices. Data flows from the SC18IS602B (master) to slave on the MOSI pin (Pin 6) and

the data flows from slave to SC18IS602B (master) on the MISO pin (Pin 5).

8.

The following example describes a typical sequence of events required to read the

contents of an SPI-based EEPROM. This example assumes that the SC18IS602B is

configured to respond to address 50h. A START condition is shown as ‘ST’, while a STOP

condition is ‘SP’. The data is presented in hexadecimal format.

1. The first message is used to configure the SPI port for mode and frequency.

ST,50,F0,02,SP

SPI frequency 115 kHz using Mode 0

2. An SPI EEPROM first requires that a Write Enable command be sent before data can

be written.

ST,50,04,06,SP

EEPROM write enable using SS2, assuming the Write Enable is

06h

3. Clear the interrupt. This is not required if using a polling method rather than interrupts.

ST,50,F1,SP

Clear interrupt

4. Write the 8 data bytes. The first byte (Function ID) tells the SC18IS602B which Slave

Select output to use. This example uses SS2 (shown as 04h). The first byte sent to

the EEPROM is normally 02h for the EEPROM write command. The next one or two

bytes represent the subaddress in the EEPROM. In this example, a two-byte

subaddress is used. Bytes 00 and 30 would cause the EEPROM to write to

subaddress 0030h. The next eight bytes are the eight data bytes that will be written to

subaddresses 0030h through 0037h.

ST,50,04,02,00,30,01,02,03,04,05,06,07,08,SP

Write 8 bytes using SS2

5. When an interrupt occurs, do a Clear Interrupt or wait until the SC18IS602B responds

ST,50,F1,SP

Clear interrupt