Motorola DSP56012 - Manual (Page 102)

4-22 DSP56012 User’s Manual MOTOROLA
Parallel Host Interface
Host Interface (HI)
transfers. The 32-bit MC68020 host processor can use its dynamic bus sizing feature
to address the HI using standard MOVE word (16-bit), long-word (32-bit) or
quad-word (64-bit) instructions. The HOREQ and HACK handshake flags are
provided for polled or interrupt-driven data transfers with the host processor.
Because the DSP interrupt response is sufficiently fast, most host microprocessors
can load or store data at their maximum programmed I/O (non-DMA) instruction
rate without testing the handshake flags for each transfer. If the full handshake is not
needed, the host processor can treat the DSP as fast memory, and data can be
transferred between the host processor and the DSP at the fastest host processor data
rate. DMA hardware can be used without host processor intervention, using the
handshake flags to transfer data.
4.4.5.2 Host Command
One of the most innovative features of the HI is the host command feature. With this
feature, the host processor can issue vectored interrupt requests to the DSP56012. The
host can select any one of sixty-four DSP56012 interrupt routines to be executed by
writing to a vector address register in the HI. This flexibility allows the host
programmer to execute up to sixty-four preprogrammed functions inside the
DSP56012. For example, host interrupts can allow the host processor to read or write
DSP56012 registers (X, Y, or program memory locations), force interrupt handlers
(e.g., SHI, SAI, DAX, IRQA, IRQB interrupt routines), and perform control and
debugging operations, if interrupt routines are implemented in the DSP56012 to
perform these tasks.