NXP Semiconductors

SC18IM704

002aac055

NUMBER

OF BYTES

S CHAR. TARGET ADR.

+ W

S CHAR.

NUMBER

OF BYTES

TARGET ADR.

+ W

DATA 0

DATA 0

DATA N

P CHAR.

DATA N

Figure 10. Repeated START: write after write

7.1.9 Power-down mode

SC18IM704 can be placed in a low-power mode. In this mode the internal oscillator is

stopped and SC18IM704 will no longer respond to the host messages. Enter the Power-

down mode by sending the power-down character Z (0x5A) followed by the two defined

bytes, which are 0x5A and followed by 0xA5. If the exact message is not received, the

device will not enter the power-down state.

Upon entering the power-down state, UART Rx pin is used to exit Deep Power-down

mode. The bridge remains in the Deep Power-down mode as long as the Rx pin remains

HIGH. Any character sent brings the bridge out of Deep Power-down mode but ignores

the character.

002aac056

Z CHAR.

0x5A

0xA5

P CHAR.

Figure 11. Power-down mode

7.1.10 Read version function ID

A read version command was included with SC18IM704 as a diagnostic tool when

bringing up the bridge to verify communication. To retrieve the version, the host must

send a ASCII ‘V’ followed by an ASCII ‘P’ character. The ‘704 will respond with a null

terminated version string. An example response:

• 0x53 0x43 0x31 0x38 0x49 0x4D 0x37 0x30 0x34 0x20 0x31 0x2E0 0x30 0x2E 0x31

0x00

Which corresponds with the ascii string “SC18IM704 1.0.1”.

The response will always be 16 characters with the last character being a 0x00 null

terminator.

connected to the bus, and it has the following features:

• Bidirectional data transfer between controllers and targets

• Multi-controller bus (no central controller)

• Arbitration between simultaneously transmitting controllers without corruption of serial

data on the bus

• Serial clock synchronization allows devices with different bit rates to communicate via

one serial bus

• Serial clock synchronization can be used as a handshake mechanism to suspend and

resume serial transfer.

SC18IM704

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© NXP B.V. 2021. All rights reserved.

Product data sheet

Rev. 1.0 — 22 September 2021

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