Stereo System User Manual

4-48 DSP56012 User’s Manual MOTOROLA
Parallel Host Interface
Host Interface (HI)
Figure 4-25 Bits Used for Host-to-DSP Transfer
0 0 Interrupt Mode (DMA Off) 0 1 24 Bit DMA Mode 1 0 16 Bit DMA Mode
11
8 Bit DMA Mode
$2
INTERRUPT STATUS REGISTER (ISR) (READ ONLY)
$0
HOST
DSP56012
TXDE—TRANSMIT DATA REGISTER EMPTY 1 = INDICATES THE TRANSMIT BYTE REGISTERS (TXH, TXM, TXL) ARE EMPTY. 0 = CLEARED BY WRITING TO TXL; TXDE CAN BE USED TO ASSERT THE HOREQ
PIN.
TRDY—TRANSMITTER READY = TXDE • HRDF 1 = BOTH THE TRANSMIT BYTE REGISTERS AND THE HOST RECEIVE DATA REGISTERS ARE EMPTY. 0 = ONE OR BOTH REGISTERS ARE FULL.
X:$FFE9
HOST STATUS REGISTER (HSR) (READ ONLY)
HRDF—HOST RECEIVE DATA FULL 1 = THE HOST RECEIVE REGISTER (HORX) CONTAINS DATA FROM THE HOST PROCESSOR. 0 = HORX IS EMPTY. DMA —INDICATES THE HOST PROCESSOR HAS ENABLED THE DMA MODE 1 = DMA ON. 0 = HOST MODE.
HOST CONTROL REGISTER (HCR) (READ/WRITE)
HRIE—HOST RECEIVE INTERRUPT ENABLE ENABLES INTERRUPT AT P:$0030 DSP INTERRUPT IS CAUSED BY HRDF = 1 1 = INTERRUPT P:$0030 ENABLED. 0 = INTERRUPT P:$0030 DISABLED.
TREQ—TRANSMIT REQUEST ENABLE USED TO ENABLE INTERRUPTS THAT COME FROM TXDE TO THE HOST VIA THE HOREQ
PIN.
1 = TXDE INTERRUPTS PASS TO HOREQ
.
0 = TXDE INTERRUPTS ARE MASKED.
INTERRUPT CONTROL REGISTER (ICR) (READ/WRITE)
X:$FFE8
HOREQ 0 HF3 TRDY TXDE
70
HF3DMA
65432 1
HF2 DMA
HF1 HF0 HTDE HRDF
70
00
65432 1
HCP
INIT HF1 HF0 TREQ RREQ
70
HM0HM1
65432 1
0 HOREQ
HF1 HF0 TREQ RREQ
70
HM0HM1
65432 1
TREQ
MODES
AA0333