Expansion Bus Interface Signals - Texas Instruments TMS320C3x User Manual

Table 9–2. Expansion Bus Interface Signals
†
Signal Type
MSTRB O/Z
IOSTRB O/Z
XR/W O/Z
XRDY I
XA (12–0) O
XD (31–0) I/O/Z
† I
Input
O Output
Z High impedance
‡ NA means not affected.
Description
Expansion bus memory access strobe
Expansion bus peripheral-access strobe
Specifies memory (active high) or write (active
low) mode
Indicates external expansion interface is ready
to be accessed
Expansion address bus. When the expansion
bus address lines are not in high-impedance
state due to HOLD signal, they keep the last
external expansion bus access.
Expansion data bus. These signals go to high-
impedance between write accesses.
TMS320C30 and TMS320C31 External-Memory Interface
Memory Interface Signals
Value
Idle Status
After Reset
1 1
1 1
1 1
‡
NA Ignored
HI Address of last external
expansion bus access
HIZ HIZ
9-5