DSP56321 datasheet(15/84 Pages) FREESCALE

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Host Interface (HI08)

DSP56321 Technical Data, Rev. 11

Freescale Semiconductor

1-9

HDS/HDS

HWR/HWR

PB12

Input

Input or Output

Ignored Input

Host Data Strobe—When the HI08 is programmed to interface with a single-

data-strobe host bus and the HI function is selected, this signal is the host data

strobe (HDS) Schmitt-trigger input. The polarity of the data strobe is

programmable but is configured as active-low (HDS) following reset.

Host Write Data—When the HI08 is programmed to interface with a double-

data-strobe host bus and the HI function is selected, this signal is the host write

data strobe (HWR) Schmitt-trigger input. The polarity of the data strobe is

programmable but is configured as active-low (HWR) following reset.

Port B 12—When the HI08 is configured as GPIO through the HI08 Port Control

HI08 Data Direction Register.

HREQ/HREQ

HTRQ/HTRQ

PB14

Output

Input or Output

Ignored Input

Host Request—When the HI08 is programmed to interface with a single host

request host bus and the HI function is selected, this signal is the host request

(HREQ) output. The polarity of the host request is programmable but is

configured as active-low (HREQ) following reset. The host request may be

programmed as a driven or open-drain output.

Transmit Host Request—When the HI08 is programmed to interface with a

double host request host bus and the HI function is selected, this signal is the

transmit host request (HTRQ) output. The polarity of the host request is

programmable but is configured as active-low (HTRQ) following reset. The host

request may be programmed as a driven or open-drain output.

Port B 14—When the HI08 is configured as GPIO through the HI08 Port Control

HI08 Data Direction Register.

HACK/HACK

HRRQ/HRRQ

PB15

Input

Output

Input or Output

Ignored Input

Host Acknowledge—When the HI08 is programmed to interface with a single

host request host bus and the HI function is selected, this signal is the host

acknowledge (HACK) Schmitt-trigger input. The polarity of the host

acknowledge is programmable but is configured as active-low (HACK) after

reset.

Receive Host Request—When the HI08 is programmed to interface with a

double host request host bus and the HI function is selected, this signal is the

receive host request (HRRQ) output. The polarity of the host request is

programmable but is configured as active-low (HRRQ) after reset. The host

request may be programmed as a driven or open-drain output.

Port B 15—When the HI08 is configured as GPIO through the HI08 Port Control

HI08 Data Direction Register.

Notes:

In the Stop state, the signal maintains the last state as follows:

• If the last state is input, the signal is an ignored input.

• If the last state is output, these lines have weak keepers that maintain the last output state even if the drivers are tri-stated.

The Wait processing state does not affect the signal state.

Table 1-10.

Host Interface (Continued)

Signal Name

Type

State During

Reset1,2

Signal Description

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