DSP56364P View Datasheet(PDF) - Motorola => Freescale

Part Name

Description

Manufacturer

DSP56364P

24-Bit Audio Digital Signal Processor

Motorola => Freescale 

Freescale Semiconductor, Inc.

Signal/Connection Descriptions

Serial Host Interface

1.7 SERIAL HOST INTERFACE

The SHI has five I/O signals that can be configured to allow the SHI to operate in either SPI or I2C mode.

Table 1-9 Serial Host Interface Signals

Signal

Name

Signal

Type

State during

Reset

Signal Description

SCK

Input or

output

SCL

Input or

output

MISO

Input or

output

SDA

Input or

open-drain

output

Tri-stated

Tri-stated

Tri-stated

Tri-stated

SPI Serial Clock—The SCK signal is an output when the SPI is configured as

a master and a Schmitt-trigger input when the SPI is configured as a slave.

When the SPI is configured as a master, the SCK signal is derived from the

internal SHI clock generator. When the SPI is configured as a slave, the SCK

signal is an input, and the clock signal from the external master synchronizes

the data transfer. The SCK signal is ignored by the SPI if it is defined as a

slave and the slave select (SS) signal is not asserted. In both the master and

slave SPI devices, data is shifted on one edge of the SCK signal and is sam-

pled on the opposite edge where data is stable. Edge polarity is determined by

the SPI transfer protocol.

I2C Serial Clock—SCL carries the clock for I2C bus transactions in the I2C

mode. SCL is a Schmitt-trigger input when configured as a slave and an

open-drain output when configured as a master. SCL should be connected to

VCC through a pull-up resistor.

This signal is tri-stated during hardware, software, and individual reset. Thus,

there is no need for an external pull-up in this state.

This input is 5 V tolerant.

SPI Master-In-Slave-Out—When the SPI is configured as a master, MISO is

the master data input line. The MISO signal is used in conjunction with the

MOSI signal for transmitting and receiving serial data. This signal is a

Schmitt-trigger input when configured for the SPI Master mode, an output

when configured for the SPI Slave mode, and tri-stated if configured for the

SPI Slave mode when SS is deasserted. An external pull-up resistor is not

required for SPI operation.

I2C Data and Acknowledge—In I2C mode, SDA is a Schmitt-trigger input

when receiving and an open-drain output when transmitting. SDA should be

connected to VCC through a pull-up resistor. SDA carries the data for I2C

transactions. The data in SDA must be stable during the high period of SCL.

The data in SDA is only allowed to change when SCL is low. When the bus is

free, SDA is high. The SDA line is only allowed to change during the time SCL

is high in the case of start and stop events. A high-to-low transition of the SDA

line while SCL is high is a unique situation, and is defined as the start event. A

low-to-high transition of SDA while SCL is high is a unique situation defined as

the stop event.

This signal is tri-stated during hardware, software, and individual reset. Thus,

there is no need for an external pull-up in this state.

This input is 5 V tolerant.

MOTOROLA

DSP56364 Advance Information

1-9

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