DSP56371 데이터 시트보기 (PDF) - Freescale Semiconductor

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DSP56371

high density CMOS device with 5.0-volt compatible inputs and outputs.

Freescale Semiconductor 

Signal/Connection Descriptions

Table 7. Serial Host Interface Signals (Continued)

Signal

Name

SS

HA2

Signal

Type

Input

Input

State

during

Reset

Signal Description

Tri-stated

SPI Slave Select—This signal is an active low Schmitt-trigger input when

configured for the SPI mode. When configured for the SPI Slave mode, this

signal is used to enable the SPI slave for transfer. When configured for the SPI

master mode, this signal should be kept deasserted (pulled high). If it is

asserted while configured as SPI master, a bus error condition is flagged. If SS

is deasserted, the SHI ignores SCK clocks and keeps the MISO output signal in

the high-impedance state.

I2C Slave Address 2—This signal uses a Schmitt-trigger input when

configured for the I2C mode. When configured for the I2C Slave mode, the HA2

signal is used to form the slave device address. HA2 is ignored in the I2C

master mode.

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

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

HREQ

Input or

Output

Internal Pull up resistor.

This input is 5 V tolerant.

Tri-stated Host Request—This signal is an active low Schmitt-trigger input when

configured for the master mode but an active low output when configured for the

slave mode.

When configured for the slave mode, HREQ is asserted to indicate that the SHI

is ready for the next data word transfer and deasserted at the first clock pulse of

the new data word transfer. When configured for the master mode, HREQ is an

input. When asserted by the external slave device, it will trigger the start of the

data word transfer by the master. After finishing the data word transfer, the

master will await the next assertion of HREQ to proceed to the next transfer.

This signal is tri-stated during hardware, software, personal reset, or when the

HREQ1–HREQ0 bits in the HCSR are cleared. There is no need for an external

pull-up in this state.

Internal Pull up resistor.

This input is 5 V tolerant.

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DSP56371 Technical Data

Freescale Semiconductor

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