SC18IM700_2

© NXP B.V. 2007. All rights reserved.

Product data sheet

Rev. 02 — 10 August 2007

6 of 22

NXP Semiconductors

SC18IM700

7.1.4 Read from 18IM internal register

The host issues the internal register read command by sending an R character followed

by the registers to be read. The frame is then terminated with a P character.

Once the command is issued, SC18IM700 will access its internal registers and returns the

contents of these registers to the host.

7.1.5 Write to GPIO port

The host issues the output port write command by sending an O character followed by the

data to be written to the output port. This command enables the host to quickly set any

GPIO pins programmed as output without having to write to the SC18IM700 internal

IOState register.

7.1.6 Read from GPIO port

The host issues the input port read command by sending an I character. This command

enables the host to quickly read any GPIO pins programmed as input without having to

read the SC18IM700 internal IOState register.

Once the command is issued, SC18IM700 will read its internal IOState register and

returns its content to the host.

7.1.7 Repeated START: read after write

The SC18IM700 also supports ‘read after write’ command as specified in the NXP

write command without having to issue a STOP condition between the two commands.

The host issues a write command as normal, then immediately issues a read command

without sending a STOP (P) character after the write command.

Fig 6.

Read from 18IM internal register

002aac051

R CHAR.

REGISTER 0

REGISTER N

P CHAR.

18IM responds

DATA 0

DATA N

Fig 7.

Write to output port

002aac052

O CHAR.

DATA

P CHAR.

Fig 8.

Read from output port

002aac053

I CHAR.

18IM responds

DATA

P CHAR.