
I-44
EPSON
S1C88348/317/316/308 TECHNICAL HARDWARE
5 PERIPHERAL CIRCUITS AND THEIR OPERATION (System Controller and Bus Control)
5.2.2 Address decoder (CE output) settings
As explained in Section 3.6.4, the S1C883xx is
equipped with address decoders that can output a
maximum of four chip enable signals (CE0–CE3) to
external devices.
The output terminals and output circuits for CE0–
CE3 are shared with output ports R30–R33. At
initial reset, they are set as output port terminals.
For this reason, when operating in a mode other
than single chip mode, the ports to be used as CE
signal output terminals must be set as such.
This setting is performed through software which
writes "1" to registers CE0–CE3 corresponding the
CE signals to be used.
Table 5.2.2.1 shows the address range assigned to
the four chip enable (CE) signals.
The arrangement of memory space for external
devices does not necessarily have to be continuous
from a subordinate address and any of the chip
enable signals can be used to assign areas in
memory. However, in the MPU mode, program
memory must be assigned to CE0.
In the expanded 512K mode, the address range of
each of the CE signals is fixed. In the expanded 64K
mode, the four address ranges, which match the
amount of memory in use, are selected with
registers CEMD0 and CEMD1.
These signals are only output when the appointed
external memory area is accessed and are not
output when internal memory is accessed.
Table 5.2.2.1 Address settings of CE0–CE3
1
0
1
0
–
00C000H–00EFFFH
006000H–007FFFH
CE3
(1) Expanded 64K mode + MCU mode (S1C88316)
(2) Expanded 64K mode + MCU mode (S1C88308)
(3) Expanded 64K mode + MPU mode (S1C88348/317/316/308)
CE0
CE1
CE2
CE3
200000H–27FFFFH
080000H–0FFFFFH
100000H–17FFFFH
180000H–1FFFFFH
000000H–00EFFFH, 010000H–07FFFFH
080000H–0FFFFFH
100000H–17FFFFH
180000H–1FFFFFH
Address range
CE signal
(4) Expanded 512K minimum/maximum modes (S1C88348/317/316/308)
MCU mode
MPU mode
CEMD0
–
008000H-00BFFFH
004000H–005FFFH
–
008000H–00EFFFH
004000H–007FFFH
00A000H–00BFFFH
004000H–00EFFFH
004000H–007FFFH
–
008000H–009FFFH
CE2
CE1
CE0
64K bytes
32K bytes
16K bytes
8K bytes
Chip size
1
0
CEMD1
1
0
1
0
–
00C000H–00EFFFH
006000H–007FFFH
CE3
CEMD0
–
008000H–00BFFFH
004000H–005FFFH
–
008000H–00EFFFH
004000H–007FFFH
002000H–003FFFH
002000H–00EFFFH
002000H–007FFFH
002000H–003FFFH
008000H–009FFFH
CE2
CE1
CE0
64K bytes
32K bytes
16K bytes
8K bytes
Chip size
1
0
CEMD1
1
0
1
0
–
00C000H–00EFFFH
006000H–007FFFH
CE3
CEMD0
–
008000H–00BFFFH
004000H–005FFFH
–
008000H–00EFFFH
004000H–007FFFH
002000H–003FFFH
000000H–00EFFFH
000000H–007FFFH
000000H–003FFFH
000000H–001FFFH
CE2
CE1
CE0
64K bytes
32K bytes
16K bytes
8K bytes
Chip size
1
0
CEMD1
Notes: "Expanded 64K mode + MCU mode" cannot be selected in the S1C88348/317.
The CE terminal status when the HALT or SLP instruction is executed in the external program
memory is different depending on the model as follows:
S1C88348/317
The CE terminal goes HIGH when the CPU enters HALT or SLEEP status.
S1C88316/308
The CE terminal does not change its status when the CPU enters HALT or SLEEP status, so
the external ROM access status will be maintained.