6 output ports (r ports), 1 configuration of output ports, 2 high impedance control – Epson S1C88650 User Manual

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S1C88650 TECHNICAL MANUAL

EPSON

5 PERIPHERAL CIRCUITS AND THEIR OPERATION (Output Ports)

5.6 Output Ports (R ports)

5.6.1 Configuration of output ports

The S1C88650 is equipped with 26 bits of output
ports (R00–R07, R10–R17, R20–R25, R30–R33).
Depending on the bus mode setting, the configura-
tion of the output ports may vary as shown in the
table below.

Table 5.6.1.1 Configuration of output ports

Terminal

R00

R01

R02

R03

R04

R05

R06

R07

R10

R11

R12

R13

R14

R15

R16

R17

R20

R21

R22

R23

R24

R25

R30

R31

R32

R33

Bus mode

Expansion

Single chip

Address A0

Address A1

Address A2

Address A3

Address A4

Address A5

Address A6

Address A7

Address A8

Address A9

Address A10

Address A11

Address A12

Address A13

Address A14

Address A15

Address A16

Address A17

Address A18

Address A19

RD signal

WR signal

Output port R30/CE0 signal

Output port R31/CE1 signal

Output port R32/CE2 signal

Output port R33/BACK signal

Output port R00

Output port R01

Output port R02

Output port R03

Output port R04

Output port R05

Output port R06

Output port R07

Output port R10

Output port R11

Output port R12

Output port R13

Output port R14

Output port R15

Output port R16

Output port R17

Output port R20

Output port R21

Output port R22

Output port R23

Output port R24

Output port R25

Output port R30

Output port R31

Output port R32

Output port R33

Only the configuration of the output ports in single
chip mode will be discussed here. With respect to
bus control, see "5.2 System Controller and Bus
Control".
Figure 5.6.1.1 shows the basic structure of the
output ports.

Data bus

Rxx

Address

Data register

Address

High impedance
control register

Fig. 5.6.1.1 Structure of output ports

In expansion mode, the data registers and high
impedance control registers of the output ports
used for bus function can be used as general
purpose registers with read/write capabilities. This
will not in any way affect bus signal output.
The output specification of each output port is as
complementary output with high impedance
control in software possible.

5.6.2 High impedance control

The output port can be high impedance controlled
in software.
This makes it possible to share output signal lines
with an other external device.

A high impedance control register is set for each
series of output port terminals as shown below.
Either complementary output and high impedance
state can be selected with this register.

Table 5.6.2.1 High impedance control registers

Output port terminal

HZR0L

HZR0H

HZR1L

HZR1H

HZR20

HZR21

HZR22

HZR23

HZR24

HZR25

HZR30

HZR31

HZR32

HZR33

R00–R03

R04–R07

R10–R13

R14–R17

R20

R21

R22

R23

R24

R25

R30

R31

R32

R33

When a high impedance control register HZRxx is
set to "1", the corresponding output port terminal
becomes high impedance state and when set to "0",
it becomes complementary output.

5.6.3 DC output

As Figure 5.6.1.1 shows, when "1" is written to the
output port data register, the output terminal
switches to HIGH (V

) level and when "0" is

written it switches to LOW (V

) level. When

output is in a high impedance state, the data
written to the data register is output from the
terminal at the instant when output is switched to
complementary.