
PEB 3445 E
Interface Description
Data Sheet
65
2001-06-29
5.1.2
The Motorola bus mode supports a 16- or 8-bit bus interface with demultiplexed or
multiplexed bus operation. For multiplexed bus operation LA(7:0) must be connected to
LD(7:0). The TE3-MUX uses the port pins LA(7:0) for the 8 bit address and the port pins
LD(15:0) for 16/8 bit data or LD(7:0) in 8-bit interface mode. A read/write access is
initiated by placing an address on the address bus and asserting LCS together with the
command signal LRDWR (see
“Motorola Bus Mode (Demultiplexed Bus Operation)”
on Page 66
). The data cycle begins when the signal LDS is asserted. Data is driven onto
the data bus either by the TE3-MUX (for read cycles) or by the external processor (for
write cycles). After a period of time, which is determined by the access time to the
internal registers valid data is placed on the bus.
In multiplexed bus operation a falling edge of LALE indicates a valid address on
LA(7:0)and the corresponding byte enable signal on LBLE. If operated in demultiplexed
bus mode LALE must be connected to V
DD3
.
Note: LCS need not to be deasserted between two subsequent cycles to the same
device.
Motorola Mode
Read cycles
Input data can be latched and the data strobe signal can be deactivated now. This
causes the TE3-MUX to remove its data from the data bus which is then tri-stated again.
Write cycles
The data strobe signal can be deactivated now. If a subsequent bus cycle is required,
the external processor can place the respective address on the address bus.
Table 6
Data Bus Access 16-bit Motorola Mode
LBLE
0
0
1
1
LA(0)
Register Access
Word access (16 bit)
Byte access (8 bit), even address
Byte access (8 bit), odd address
no data transfer
Data Pins Used
LD(15:0)
LD(15:8)
LD(7:0)
-
0
1
0
1