HOST INTERFACE (HI)
MOTOROLA
PORT B
5 - 35
5.3.5.1
HI Host Processor Data Transfer
The HI looks like static RAM to the host processor. Accordingly, in order to transfer data
with the HI, the host processor:
1. asserts the HI address (HA0, HA1, HA2) to select the register to be read or written
2. asserts HR/W to select the direction of the data transfer
3. strobes the data transfer using HEN. When data is being written to the HI by the
host processor, the positive-going edge of HEN latches the data in the HI register
selected. When data is being read by the host processor, the negative-going edge
of HEN strobes the data onto the data bus H0-H7
Figure 5-15 illustrates this process. The specified timing relationships are given in the
DSP56002 Technical Data Sheet.
5.3.5.2
HI Interrupts Host Request (HREQ)
The host processor interrupts are external and use the HREQ pin. HREQ is normally con-
nected to the host processor maskable interrupt (IPL0, IPL1 or IPL2 in Figure 5-16) input.
The host processor acknowledges host interrupts by executing an interrupt service rou-
2. THE HOST PROCESSOR ASSERTS HACK WITH ITS INTERRUPT
ACKNOWLEDGE CYCLE.
1K
7
0
DSP56002
A1 - A31
FC0 - FC2
AS
IPL2
IPL1
IPL0
D0 - D7
HREQ
HACK
H0 - H7
IACK
LOGIC
$0F
$3
+5 V
INTERRUPT VECTOR NUMBER
INTERRUPT VECTOR REGISTER (IVR)
(READ/WRITE)
MC68000
1. THE DSP56002 ASERTS HREQ TO INTERRUPT THE HOST PROCESSOR.
3. WHEN HREQ AND HACK ARE SIMULTANEOUSLY ASSERTED, THE
CONTENTS OF THE IVR ARE PLACED ON THE HOST DATA BUS.
IACK
INTERRUPT
VECTOR
REGISTER
(IVR)
Figure 5-16 Interrupt Vector Register Read Timing
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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