CDP6402, CDP6402C
TABLE 2. FUNCTION PIN DEFINITION
PIN
1
2
3
4
SYMBOL
V
DD
N/C
GND
RRD
Positive Power Supply
No Connection
Ground (V
SS
)
A high level on RECEIVER REGISTER DISABLE forces the receiver holding register ouputs RBR1-RBR8 to
a high impedance state.
The contents of the RECEIVER BUFFER REGISTER appear on these three-state outputs. Word formats less
than 8 characters are right justified to RBR1.
DESCRIPTION
5
RBR8
6
7
8
9
10
11
12
13
RBR7
RBR6
RBR5
RBR4
RBR3
RBR2
RBR1
PE
A high level on PARITY ERROR indicates that the received parity does not match parity programmed by control
bits. The output is active until parity matches on a succeeding character. When parity is inhibited, this output
is low.
A high level on FRAMING ERROR indicates the first stop bit was invalid. FE will stay active until the next valid
character’s stop bit is received.
A high level on OVERRUN ERROR indicates the data received flag was not cleared before the last character
was transferred to the receiver buffer register. The Error is reset at the next character’s stop bit if DRR has been
performed (i.e., DRR; active low).
A high level on STATUS FLAGS DISABLE forces the outputs PE, FE, OE, DR, TBRE to a high impedance
state.
The RECEIVER REGISTER CLOCK is 16X the receiver data rate.
A low level on DATA RECEIVED RESET clears the data received output (DR), to a low level.
A high level on DATA RECEIVED indicates a character has been received and transferred to the receiver buffer
register.
Serial data on RECEIVER REGISTER INPUT is clocked into the receiver register.
A high level on MASTER RESET (MR) clears PE, FE, OE and DR, and sets TRE, TBRE, and TRO. TRE is
actually set on the first rising edge of TRC after MR goes high. MR should be strobed after power-up.
A high level on TRANSMITTER BUFFER REGISTER EMPTY indicates the transmitter buffer register has
transferred its data to the transmitter register and is ready for new data.
A low level on TRANSMITTER BUFFER REGISTER LOAD transfers data from inputs TBR1-TBR8 into the
transmitter buffer register. A low to high transition on TBRL requests data transfer to the transmitter register. If
the transmitter register is busy, transfer is automatically delayed so that the two characters are transmitted end
to end.
A high level on TRANSMITTER REGISTER EMPTY indicates completed transmission of a character including
stop bits.
See Pin 5 - RBR8
14
FE
15
OE
16
SFD
17
18
19
RRC
DRR
DR
20
21
RRl
MR
22
TBRE
23
TBRL
24
TRE
5-80
HARRIS [ HARRIS CORPORATION ]
