
S1C88409 TECHNICAL MANUAL
EPSON
77
CHAPTER 5: PERIPHERAL CIRCUITS AND OPERATION (Output Ports)
Table 5.7.5.1(b) Output port control bits
Address
Function
R/W
Init
0
1
Comment
Name
Bit
00FFD8
–
R32 output port data register
R31 output port data register
R30 output port data register
–
R/W
–
1
–
Low
–
High
"0" when being read
–
R32D
R31D
R30D
D7
D6
D5
D4
D3
D2
D1
D0
00FFD9
–
R42 output port data register
R41 output port data register
R40 output port data register
–
R/W
–
1
–
Low
–
High
"0" when being read
–
R42D
R41D
R40D
D7
D6
D5
D4
D3
D2
D1
D0
00FFD7
R27 output port data register
R26 output port data register
R25 output port data register
R24 output port data register
R23 output port data register
R22 output port data register
R21 output port data register
R20 output port data register
R/W
1
Low
High
R27D
R26D
R25D
R24D
R23D
R22D
R21D
R20D
D7
D6
D5
D4
D3
D2
D1
D0
HZR00–HZR07: R0 port high impedance control
register (00FFD0H)
HZR10–HZR17: R1 port high impedance control
register (00FFD1H)
HZR20–HZR27: R2 port high impedance control
register (00FFD2H)
HZR30–HZR32: R3 port high impedance control
register (00FFD3HD0–D2)
HZR40–HZR42: R4 port high impedance control
register (00FFD4HD0–D2)
Sets the output terminals into a high impedance
state.
When "1" is written: High impedance
When "0" is written: Complementary
Reading: Valid
The HZR register is the high impedance control
register corresponding to each output port.
When a HZR bit is set to "1", the corresponding
output port terminal goes to a high impedance
status and when "0" is set, it becomes a comple-
mentary output.
The high impedance control register of the output
port which is used for bus function can be used as
a general purpose register with the ability to read
and write. It does not affect the bus signal output.
Among R40 to R42, the high-impedance control
register of the port which is used for special
output (TOUT/FOUT, BZ) should be fixed at "0".
At initial reset, the HZR register is set to "1" (high
impedance).
R00D–R07D: R0 port output data register
(00FFD5H)
R10D–R17D: R1 port output data register
(00FFD6H)
R20D–R27D: R2 port output data register
(00FFD7H)
R30D–R32D: R3 port output data register
(00FFD8HD0–D2)
R40D–R42D: R4 port output data register
(00FFD9HD0–D2)
Sets the data output from the output port terminal.
When "1" is written: HIGH level output
When "0" is written: LOW level output
Reading: Valid
RxxD is the data register for each output port.
When "1" is set, the corresponding output port
terminal goes high (VDD) level, and when "0" is set,
it goes low (VSS) level.
The data register of the output port which is used
for the bus function can be used as general pur-
pose register with the ability to read and write. It
does not affect the bus signal output.
Among R40 to R42, the data register of the port
which is used for special output (TOUT/FOUT,
BZ) should be fixed at "1".
At initial reset, all the data bits are set to "1"
(HIGH level output).