
OctalLIU
TM
PEF 22508 E
Pin Descriptions
Data Sheet
20
Rev. 1.0, 2005-06-02
H15
WR
I
PU
Write Enable
Intel bus mode.
This signal indicates a write operation. When CS is
active the OctalLIU
TM loads an internal register with
data provided on the data bus.
RW
I
PU
Read/Write Select
Motorola bus mode.
This signal distinguishes between read and write
operation.
R5
DBW
I
PU
Data Bus Width select
Bus interface mode
A low signal on this input selects the 8-bit bus interface
mode. A high signal on this input selects the 16-bit bus
interface mode. In this case word transfer to/from the
internal registers is enabled. Byte transfers are
implemented by using A0 and BHE/BLE.
H13
BHE
I
PU
Bus High Enable
Intel bus mode.
If 16-bit bus interface mode is enabled, this signal
indicates a data transfer on the upper byte of the data
bus D(15:8). In 8-bit bus interface mode this signal has
no function and should be tied to VDD or left open.
BLE
I
PU
Bus Low Enable
Motorola bus mode.
If 16-bit bus interface mode is enabled, this signal
indicates a data transfer on the lower byte of the data
bus D(7:0). In 8-bit bus interface mode this signal has
no function and should be tied to VDD or left open.
H12
CS
I
PU
Chip Select
Low active chip select.
H11
INT
O
–
Interrupt Request
Interrupt request.
INT serves as general interrupt request for all interrupt
sources. These interrupt sources can be masked via
registers IMR(7:0). Interrupt status is reported via
registers GIS (Global Interrupt Status) and ISR(7:0).
Output characteristics (push-pull active low/high, open
drain) are determined by programming register IPC.
G14
READY
O
–
Data Ready
Only if Intel bus mode is selected.
Asynchronous handshake signal to indicate successful
read or write cycle.
DTACK
O
–
Data Acknowledge
Only if Motorola bus mode is selected.
Asynchronous handshake signal to indicate successful
read or write cycle.
Line Interface Receiver
Table 1
I/O Signals (cont’d)
Pin No. Ball
No.
Name
Pin Type Buffer
Type
Function