HD-15531
DECODER
7
8
SYNCHRONOUS
DATA SELECT
SYNCHRONOUS
DATA
13
UNIPOLAR
DATA IN
4
TAKE DATA
DATA
SELECT
GATE
12
11
17
TRANSITION
FINDER
CHARACTER
IDENTIFIER
BIPOLAR
ONE IN
COMMAND SYNC
BIPOLAR
ONE IN
DATA SYNC
5
SERIAL
DATA OUT
9
2
DECODER
CLK
VALID WORD
CLOCK
SELECT
DATA
BIT
RATE
CLK
PARITY
SYNCHRONIZER
16
CHECK
PARITY
SELECT
15
DECODER
CLK SELECT
8
SYNCHRONOUS
CLK
14
DECODER
SHIFT CLK
10
22
SYNCHRONOUS
CLK SELECT
MASTER
RESET
19
3
BIT
COUNTER
DECODER
RESET
TAKE DATA’
20 40 23 36 39
C
C
C
C
C
4
0
1
2
3
Pin Description
PIN
NUMBER TYPE
NAME
SECTION
DESCRIPTION
1
V
Both
Positive supply pin. A 0.1µF decoupling capacitor from V
(pin 1) to GROUND
CC
CC
(pin 21) is recommended.
2
3
O
O
VALID WORD
TAKE DATA’
Decoder Output high indicates receipt of a valid word, (valid parity and no Manchester
errors).
Decoder A continuous, free running signal provided for host timing or data handling. When
data is present on the bus, this signal will be synchronized to the incoming data
and will be identical to TAKE DATA.
4
O
TAKE DATA
Decoder Output is high during receipt of data after identification of a valid sync pulse and
two valid Manchester bits.
5
6
O
I
SERIAL DATA OUT
Decoder Delivers received data in correct NRZ format.
SYNCHRONOUS
DATA
Decoder Input presents Manchester data directly to character identification logic.
SYNCHRONOUS DATA SELECT must be held high to use this input. If not
used, this pin must be held high.
7
I
I
I
I
I
I
I
SYNCHRONOUS
DATA SELECT
Decoder In high state allows the synchronous data to enter the character identification
logic. Tie this input low for asynchronous data.
8
SYNCHRONOUS
CLOCK
Decoder Input provides externally synchronized clock to the decoder, for use when re-
ceiving synchronous data. This input must be tied high when not in use.
9
DECODER CLOCK
Decoder Input drives the transition finder, and the synchronizer which in turn supplies the
clock to the balance of the decoder. Input a frequency equal to 12X the data rate.
10
11
12
13
SYNCHRONOUS
CLOCK SELCT
Decoder In high state directs the SYNCHRONOUS CLOCK to control the decoder char-
acter identification logic. A low state selects the DECODER CLOCK.
BIPOLAR ZERO IN
BIPOLAR ONE IN
UNIPOLAR DATA IN
Decoder A high input should be applied when the bus is in its negative state. This pin must
be held high when the unipolar input is used.
Decoder A high input should be applied when the bus is in its positive state. This pin must
he held low when the unipolar input is used.
Decoder With pin 11 high and pin 12 low, this pin enters unipolar data into the transition
finder circuit. If not used this input must be held low.
3