Stereo System User Manual

4-58 DSP56012 User’s Manual MOTOROLA
Parallel Host Interface
Host Interface (HI)
Figure 4-33 Data Transfer from DSP to Host
VIEW FROM HOST
X:$FFE8
HOST CONTROL REGISTER (HCR)
1. WHEN HTDE = 1, THEN HOTX IS EMPTY. 2. DSP56012 can POLL HTDE.
7. THE TRANSFER SETS RXDF FOR THE HOST TO POLL.
HTDE
HOST TRANSMIT DATA EMPTY
HTIE
HOST TRANSMIT INTERRUPT ENABLE
P:$007E
AVAILABLE FOR HOST COMMAND
FAST INTERRUPT
OR
LONG INTERRUPT
P:$0000
HOST TRANSMIT DATA VECTOR
P:$0032
5. READ OF RXL BY HOST CLEARS RXDF IN ISR. 6. WHEN RXDF = 0 AND HTDE = 0, THEN TRANSFER OCCURS.
RXH
RXM
RXL
70
$5 $6
LAST READ $7
RECEIVE BYTE
REGISTERS (RBR)
$2
RXDF
RECEIVE
DATA FULL
$0
RREQ
RECEIVE
REQUEST ENABLE
8. IF RREQ = 1, THEN HOREQ PIN IS ASSERTED TO INTERRUPT HOST.
HOREQ
PIN
VIEW FROM HOST
3. IF HTIE = 1, AND INTERRUPTS ARE ENABLED, THEN INTERRUPT
PROCESSING BEGINS.
4. DSP56012 WRITES DATA TO HOTX, WHICH CLEARS HTDE IN HSR.
X:$FFEB
HOST TRANSMIT D ATA REGISTER (HOTX)
INTERRUPT STATUS REGISTER (ISR)
HOREQ
HF3 HF2 TXDE 1
70
0DMA
65432 1
TRDY
$X:$FFE9
HOST STATUS REGISTER (HSR)
DMA
HF1 HF0 1 HRDF
70
00
65432 1
HCP
0
HF3 HF2 1 HRIE
70
00
65432 1
HCIE
INIT HF1 HF0 TREQ 1
70
HM0HM1
65432 1
0
HIGH BYTE
LOW BYTE
23 0
MIDDLE BYTE
INTERRUPT CONTROL REGISTER (ICR)
AA0340K