4-10 DSP56012 User’s Manual MOTOROLA

Parallel Host Interface
Host Interface (HI)

4.4.1 HI Features

•Speed—6.6 million words/sec (19.8 MBytes/sec) Interrupt Driven Data
Transfer Rate (this is the maximum interrupt rate for the DSP56012 running at
81 MHz)
• Signals (fifteen pins):
– H[7:0]—HI data bus
– HOA[2:0]—HI Address select
– HEN—HI Enable
– HR/W—HI Read/Write select
– HOREQ—HI Request
– HACK —HI Acknowledge
•Interface—DSP CPU side:
– Mapping: three X-memory locations
– Data Word: 24 bits
– Transfer Modes:
• DSP-to-Host
• Host-to-DSP
• Host Command
• Handshaking Protocols
– Software polled
– Interrupt-driven (fast or long interrupts)
– Direct Memory Access (DMA)
• Instructions
– Memory-mapped registers allow the standard MOVE instruction to be
used.
– Special MOVEP instruction provides for I/O service capability using fast inter
rupts.
– Bit addressing instructions (BCHG, BCLR, BSET, BTST, JCLR, JSCLR, JSET,
JSSET) simplify I/O service routines.