Motorola DSP56012 4.4.8 Host Interface Application Examples

4-42 DSP56012 User’s Manual MOTOROLA
Parallel Host Interface
Host Interface (HI)
4.4.8 Host Interface Application Examples
The following paragraphs describe examples of initializing the HI, transferring data
with the HI, bootstrapping via the HI, and performing DMA transfers through the
HI.
4.4.8.1 HI Initialization
Initializing the HI takes two steps (see Figure 4-18). The first step is to initialize the
DSP side of the HI, which requires that the options for interrupts and flags be
selected and then the HI be selected (see Figure 4-19 on page 4-43). The second step
is for the host processor to clear the HC bit by writing the CVR, select the data
transfer method-polling, interrupts, or DMA (see Figure 4-25 on page 4-48 and
Figure 4-26 on page 4-50), and write the IVR (in the case of an MC680XX family host
processor). Figure 4-19 on page 4-43 through Figure 4-22 on page 4-46 provide a
general description of how to initialize the HI. Later paragraphs in this section
provide more detailed descriptions of specific examples. These subsections include
some code fragments illustrating how to initialize and transfer data using the HI.
Figure 4-18 HI Initialization Flowchart
Step 1
The DSP CPU initializes the DSP side
of the HI by writing:
1) HCR at X:$FFE8 and
2) PBC at X:$FFE0
STEP 2
The Host Processor initializes the host
side of the HI by writing:
1) ICR at $0 and/or
2) CVR at $1 and/or
3) IVR at $3 AA0326k