Parallel Host Interface
Host Interface (HI)

MOTOROLA DSP56012 User’s Manual 4-63

Figure 4-37 Host to DSP DMA Procedure

WRITE ICR
HOST PROCESSOR
X:$FFE8 HOST CONTROL
REGISTER (HCR)
P:$007E AVAILABLE FOR HOST COMMAND
FAST INTERRUPT
OR
LONG INTERRUPT
P:$0000
HOST TRANSMIT D ATA VECT OR
P:$0032
1. PROGRAM DMA CONTROLLER.
—START ADDRESS
—BYTE COUNT
—TRANSFER DIRECTION
—START DMA CHANNEL
TXH
TXM
TXL
TXH
TXM
TXL
•
•
•
TXH
TXM
TXL
01
10
11
01
10
11
01
10
11
DSP56012DMA CONTROLLER
2. INITIALIZE DSP56012 HOST INTERFACE.
—MODE 24 BIT DMA
—HOST T O DSP
—USE INIT BIT TO:
SET TXDE
CLEAR HRDF
LOAD DMA COUNTER
5. HOST IS FREE TO PERFORM
OTHER TASKS (i.e., DSP TO HOST
TRANSFER ON A POLLED BASIS).
8. TERMINATE DMA CHANNEL.
9. TERMINATE DSP DMA MODE BY
CLEARING HM1, HM0, AND TREQ.
7. DMA CONTROLLER INTERRUPTS HOST
WHEN TRANSFERS ARE DONE.
HOREQ
PIN
6. DMA CONTROLLER PERFORMS READS.
$0
INTERRUPT
CONTROL
REGISTER (ICR)
4. ASSERT HOREQ TO START DMA TRANSFER.
interrupt VECTOR TABLE
3. TELL DSP56012
—WHERE TO STORE DATA (i.e., PROGRAM
ADDRESS REGISTER R7).
—ENABLE INTERRUPT HRIE (CAN BE
DONE WITH A HOST COMMAND).
1 HF1 HF0 1 0
70
10
654321
0
INIT HM1 HM0 TREQ RREQ
0HF3 HF2 HTIE 1
70
00
654321
HCIE
HRIE
AA0343.11

Note: When using the SAI and DAX

peripherals, do not use interrupt vector

addresses P:$0040–$004A, $0050,

$0052, and $0056.