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 D ATA VECT OR
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
DATA
REGISTER (HOTX)
INTERRUPT
STATUS
REGISTER (ISR)
HOREQ HF3 HF2 TXDE 1
70
0DMA
654321
TRDY
$X:$FFE9 HOST STATUS
REGISTER (HSR)
DMA HF1 HF0 1 HRDF
70
00
654321
HCP
0HF3 HF2 1 HRIE
70
00
654321
HCIE
INIT HF1 HF0 TREQ 1
70
HM0HM1
654321
0
HIGH BYTE LOW BYTE
23 0
MIDDLE BYTE
INTERRUPT
CONTROL
REGISTER (ICR)
AA0340K