Stereo System User Manual

Parallel Host Interface

Host Interface (HI)

MOTOROLA DSP56012 User’s Manual 4-37

4.4.7 Servicing the HI

The HI can be serviced by using one of the following protocols:

• Polling

• Interrupts, which can be either:

– non-DMA

– DMA

From the host processor viewpoint, the service consists of making a data transfer,

since this is the only way to reset the appropriate status bits.

4.4.7.1 HI—Host Processor Data Transfer

The HI looks like Static RAM to the host processor. Accordingly, in order to transfer

data with the HI, the host processor:

1. asserts the Host Address (HOA[2:0]) to select the register to be read or written;

2. asserts HR/W

to select the HI for the current access, and

Figure 4-14 Host Processor Transfer Timing

HOA0–HOA2

H[7:0]

DSP56012

HOA0–HOA2

H[7:0]

HOREQ

HACK

Write ReadData

Latched

In Host

AA0322.11

HEN

HR/W

HEN

HR/W