Motorola DSP56012 4.4.7 Servicing the HI

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
8
3
+5
+5
AA0322.11
HEN
HR/W
HEN
HR/W