PRELIMINARY
PCT1789W DATA SHEET
PCT789T-A CONTROL REGISTERS
!!
External Output
(Register 2, W)
Reserved
EXTOUT[7:0]
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Bit Definitions:
Bits
15:8
7:0
Name
Description
Reserved.
Reserved
EXTOUT[7:0]
External output register (default 00h). Directly drives four programmable output
pins.
EXTOUT[7:4]: OUT[7:4].
EXTOUT[3]: mute speaker.
EXTOUT[2]: handset relay control.
EXTOUT[1]: Caller ID relay control.
EXTOUT[0]: OFF-Hook relay control.
External Input
(Register 2, R)
Reserved
10
EXTIN[3:0]
15
14
13
12
11
9
8
7
6
5
4
3
2
1
0
Bit Definitions:
Bits
15:4
3:0
Name
Description
Reserved.
Reserved
EXTIN[3:0]
External input register allows system to monitor four programmable input pins.
EXTIN[3:2]: IN[1:0]
EXTIN[1]: ILC-Sense (or handset detect) input.
EXTIN[0]: ring detect input.
Miscellaneous Control
(Register 3, W)
Reserved
TOC[3:0]
10
FFSZ[7:0]
15
14
13
12
11
9
8
7
6
5
4
3
2
1
0
Bit Definitions:
Bits
15:12
Name
Description
Reserved.
Reserved
TOC[3:0]
11:8
Time-out count register (default 00h). Allows PCT789T-A to generate internal
time-out if errors detected for (N+1)*256*FFSZ*1/Sampling Frequency, where
N=0–15.
7:0
FFSZ[7:0]
FIFO size control register (default 20h). Allows Tx and Rx buffer size to be chosen
up to 128 words deep (the legal number accepted is between 16 and 128). When-
ever the Rx buffer is full, INTA is generated, if enabled.
Error Count
(Register 3, R)
Reserved
14 13
ERRCNT[11:0]
15
12
11
10
9
8
7
6
5
4
3
2
1
0
Bit Definitions:
Bits
15:12
Name
Description
Reserved.
Reserved
PRELIMINARY
PC-TEL, Inc.
38
1789W0DOCDAT06A-0299
ETC [ ETC ]
