OP7100
Hardware 45
Asynchronous Serial Communication Interface
The Z180 incorporates an asynchronous serial communication interface
(ACSI) that supports two independent full-duplex channels.
ASCI Status Registers
A status register for each channel provides information about the state of
each channel and allows interrupts to be enabled and disabled.
STAT0
(04H)
7
6
5
4
3
2
1
0
RDRF
OVRN
PE
FE
RIE
/DCD0
TDRE
TIE
R
R
R
R
R / W
R
R
R / W
STAT1
(05H)
7
6
5
4
3
2
1
0
RDRF
OVRN
PE
FE
RIE
CTS1E
TDRE
TIE
R
R
R
R
R / W
R
R
R / W
/DCD0 (Data Carrier Detect)
This bit echoes the state of the
/DCD0
input pin for Channel 0. However,
when the input to the pin switches from high to low, the data bit switches
low only after STAT0 has been read. The receiver is held to reset as long
as the input pin is held high. This function is not generally useful because
an interrupt is requested as long as
/DCD0
is a 1. This forces the program-
mer to disable the receiver interrupts to avoid endless interrupts. A better
design would cause an interrupt only when the state of the pin changes.
This pin is tied to ground in the CM7000.
TIE (Transmitter Interrupt Enable)
This bit masks the transmitter interrupt. If set to 1, an interrupt is requested
whenever TDRE is 1. The interrupt is not edge-triggered. Set this bit to 0
to stop sending. Otherwise, interrupts will be requested continuously as
soon as the transmitter data register is empty.
TDRE (Transmitter Data Register Empty)
A 1 means that the channel is ready to accept another character. A high
level on the
/CTS
pin forces this bit to 0 even though the transmitter is
ready.
Summary of Contents for OP7100
Page 1: ...OP7100 Serial Graphic Display User s Manual 019 0065 070831 O ...
Page 10: ...OP7100 x About This Manual ...
Page 16: ...OP7100 16 Overview ...
Page 74: ...OP7100 74 Software ...
Page 82: ...OP7100 82 Graphics Programming ...
Page 88: ...OP7100 88 Installation ...
Page 98: ...OP7100 98 Specifications ...
Page 108: ...OP7100 108 Memory I O Map and Interrupt Vectors ...
Page 112: ...112 Serial Interface Board 2 OP7100 ...
Page 113: ...OP7100 Backup Battery 113 APPENDIX E BACKUP BATTERY ...
Page 116: ...OP7100 116 Backup Battery ...
Page 124: ...OP7100 124 Index ...
Page 126: ...XX0000 Schematics ...