Motorola DSP56012 - Manual (Page 130)

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
0
DMA
6
5
432
1
00
HF1
HF0
HTDE
0
70
0
0 6
5
432
1
HCP
INIT
HF1
HF0
1
RREQ
70
0
0 6
5
432
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
0
0 6
5
432
1
HCIE
7.
WHEN DSP56012 READS HORX, THEN HRDF = 0.
6.
IF DSP56012 HAS OLD DATA IN HORX, THEN HRDF = 1.
70
AA0334