Stereo System User Manual

4-50 DSP56012 User’s Manual MOTOROLA
Parallel Host Interface
Host Interface (HI)
Figure 4-26 Data Transfer from Host to DSP
TRANSFER
$2
INTERRUPT STATUS REGISTER (ISR)
$0
VIEW FROM HOST VIEW FROM DSP56012
1. WHEN TXDE = 1, TDR IS EMPTY.
X:$FFE9
HOST STATUS REGISTER (HSR)
X:$FFE8
HOST CONTROL REGISTER (HCR)
TXDE
TRANSMIT DATA REGISTER EMPTY
INTERRUPT CONTROL REGISTER (ICR)
2. HOST can POLL TXDE.
TREQ
TRANSMIT REQUEST ENABLE
3. IF TREQ = 1, THEN HOREQ PIN IS ASSERTED TO INTERRUPT HOST.
HOREQ
PIN
4. HOST WRITES DATA TO TRANSMIT BYTE REGISTERS. 5. WRITE TO TXL CLEARS TXDE IN ISR.
TRANSMIT BYTE
REGISTERS (TBR)
8. WHEN TXDE = 0 AND HRDF = 0, THEN TRANSFER OCCURS.
HRDF
HOST RECEIVE DATA FULL
DMA
X:$FFEB
HOST RECEIVE DATA REGISTER (HORX)
9. THE TRANSFER SETS HRDF FOR THE DSP56012 TO POLL.
HRIE
HOST RECEIVE INTERRUPT ENABLE
P:$0030 HOST RECEIVE DATA VECTOR
FAST INTERRUPT
OR
LONG INTERRUPT
HOREQ HF3 HF2 1 RXDF
70
0DMA
65432 1
00HF1 HF0 HTDE 0
70
00
65432 1
HCP
INIT
HF1 HF0 1 RREQ
70
00
65432 1
0
HM1 HM0
HIGH BYTE
23 0
MIDDLE BYTE LOW BYTE
LAST WRITE
$5 $6 $7
TXH
TXM
TXL
10. IF HRDF = 1 AND INTERRUPTS ARE ENABLED, THEN
interrupt PROCESSING BEGINS.
0 HF3 HF2 HTIE 1
70
00
65432 1
HCIE
7. WHEN DSP56012 READS HORX, THEN HRDF = 0.
6. IF DSP56012 HAS OLD DATA IN HORX, THEN HRDF = 1.
70
AA0334