5-3
Pin Description
PIN
NUMBER TYPE SYMBOL NAME DESCRIPTION
1 I BZl Bipolar Zero Input Used in conjunction with pin 2, Bipolar One Input (BOl), to input Manchester II
encoded data to the decoder, BZI and BOl are logical complements. When using
pin 3, Unipolar Data Input (UDI) for data input, BZI must be held high.
2 I BOl Bipolar One Input Used in conjunction with pin 1, Bipolar Zero Input (BZI), to input Manchester II
encoded data to the decoder, BOI and BZI are logical complements. When using
pin 3, Unipolar Data Input (UDI) for data input, BOl must be held low.
3 I UDI Unipolar Data Input An alternate to bipolar input (BZl, BOl), Unipolar Data Input (UDl) is used to input
Manchester II encoded data to the decoder. When using pin 1 (BZl) and pin 2
(BOl) for data input, UDI must be held low.
4 I/O SD/CDS Serial Data/Com-
mand Data Sync
In the converter mode, SD/CDS is an input used to receive serial NRZ data. NRZ
data is accepted synchronously on the falling edge of encoder clock output
(ECLK). In the repeater mode, SD/CDS is an output indicating the status of last
valid sync pattern received. A high indicates a command sync and a low indicates
a data sync pattern.
5 O SDO Serial Data Out The decoded serial NRZ data is transmitted out synchronously with the decoder
clock (DCLK). SDO is forced low when RST is low.
6OSRST Serial Reset In the converter mode, SRST follows RST. In the repeater mode, when RST goes
low, SRST goes low and remains low after RST goes high. SRST goes high only
when RST is high, the reset bit is zero, and a valid synchronization sequence is
received.
7ONVM Nonvalid Manchester A low on NVM indicates that the decoder has received invalid Manchester data
and present data on Serial Data Out (SDO) is invalid. A high indicates that the
sync pulse and data were valid and SDO is valid. NVM is set low by a low on RST,
and remains low after RST goes high until valid sync pulse followed by two valid
Manchester bits is received.
8 O DCLK Decoder Clock The decoder clock is a 1X clock recovered from BZl and BOl, or UDI to synchro-
nously output received NRZ data (SDO).
9IRST Reset In the converter mode, a low on RST forces SDO, DCLK, NVM, and SRST low.
A high on RST enables SDO and DCLK, and forces SRST high. NVM remains
low after RST goes high until a valid sync pulse followed by two Manchester bits
is received, after which it goes high. In the repeater mode, RST has the same ef-
fect on SDO, DCLK and NVM as in the converter mode. When RST goes low,
SRST goes low and remains low after RST goes high. SRST goes high only
when RST is high, the reset bit is zero and a valid synchronization sequence is
received.
10 I GND Ground Ground
11 O C
O
Clock Output Buffered output of clock input I
X
. May be used as clock signal for other peripherals.
12 I I
X
Clock Input I
X
is the input for an external clock or, if the internal oscillator is used, I
X
and O
X
are used for the connection of the crystal.
13 O O
X
Clock Drive If the internal oscillator is used, O
X
and I
X
are used for the connection of the crys-
tal.
14 I MS Mode Select MS must be held low for operation in the converter mode, and high for operation
in the repeater mode.
15 I CTS Clear to Send In the converter mode, a high disables the encoder, forcing outputs BOO, BZO high
and ECLK low. A high to low transition of CTS initiates transmission of a Command
sync pulse. A low on CTS enables BOO, BZO, and ECLK. In the repeater mode,
the function of CTS is identical to that of the converter mode with the exception that
a transition of CTS does not initiate a synchronization sequence.
16 O ECLK Encoder Clock In the converter mode, ECLK is a 1X clock output used to receive serial NRZ data
to SD/CDS. In the repeater mode, ECLK is a 2X clock which is recovered from
BZl and BOl data by the digital phase locked loop.
HD-6409
