DATASHEET
82C52
CMOS Serial Controller Interface
The Intersil 82C52 is a high performance programmable
Universal Asynchronous Receiver/Transmitter (UART) and
Baud Rate Generator (BRG) on a single chip. Utilizing the
Intersil advanced Scaled SAJI IV CMOS process, the 82C52
will support data rates up to 1M baud asynchronously with a
16X clock (16MHz clock frequency).
The on-chip Baud Rate Generator can be programmed for any
one of 72 different baud rates using a single industry standard
crystal or external frequency source. A unique pre-scale divide
circuit has been designed to provide standard RS-232-C baud
rates when using any one of three industry standard crystals
(1.8432MHz, 2.4576MHz, or 3.072MHz).
A programmable buffered clock output (CO) is available and
can be programmed to provide either a buffered oscillator or
16X baud rate clock for general purpose system usage.
FN2950
Rev 4.00
November 25, 2015
Features
• Single Chip UART/BRG
• DC to 16MHz (1M Baud) Operation
• Crystal or External Clock Input
• On-Chip Baud Rate Generator - 72 Selectable Baud Rates
• Interrupt Mode with Mask Capability
• Microprocessor Bus Oriented Interface
• 80C86 Compatible
• Single +5V Power Supply
• Low Power Operation . . . . . . . . . . . . . . . . . . . . 1mA/MHz Typ
• Modem Interface
• Line Break Generation and Detection
• Operating Temperature Range:
- C82C52 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0°C to +70°C
- I82C52. . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40°C to +85°C
- M82C52. . . . . . . . . . . . . . . . . . . . . . . . . . . -55°C to +125°C
• Pb-Free Plus Anneal Available (RoHS Compliant)
•
Ordering Information
1M BAUD
PART MARKING
TEMP
RANGE (°C)
0 to +70
PDIP
PACKAGE
PKG. DWG. #
E28.6
CP82C52
CP82C52
(No longer available or supported
Recommended Replacement:
CP82C52Z)
CP82C52Z (Note)
IP82C52
CS82C5296
CS82C52Z*
(Note)
IS82C52
IS82C52Z*
(Note)
ID82C52
MD82C52/B
8501501XA
MR82C52/B
85015013A
*Add "96" suffix for tape and reel.
85015013A
CP82C52Z
IP82C52
CS82C52
CS82C52Z
IS82C52
IS82C52Z
ID82C52
MD82C52/B
8501501XA
0 to +70
-40 to +85
0 to +70
0to +70
-40 to +85
-40 to +85
-40 to +85
-55 to +125
PDIP (Pb-Free)**
PDIP
PLCC (Tape & Reel)
PLCC
(Pb-Free)
PLCC
PLCC
(Pb-Free)
CERDIP
E28.6
E28.6
N28.45
N28.45
N28.45
N28.45
F28.6
F28.6
SMD#
-55 to +125
CLCC
SMD#
F28.6
J28.A
J28.A
**Pb-free PDIPs can be used for through hole wave solder processing only. They are not intended for use in Reflow solder processing applications.
NOTE: Intersil Pb-free plus anneal products employ special Pb-free material sets; molding compounds/die attach materials and 100% matte tin plate
termination finish, which are RoHS compliant and compatible with both SnPb and Pb-free soldering operations. Intersil Pb-free products are MSL
classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020.
FN2950 Rev 4.00
November 25, 2015
Page 1 of 21
82C52
Pinouts
82C52 (PDIP, CERDIP)
TOP VIEW
D1
RD 1
WR 2
D0 3
D1 4
D2 5
D3 6
D4 7
D5 8
D6 9
D7 10
A0 11
A1 12
IX 13
OX 14
28 CSO
27 VCC
26 DR
25 SDI
24 INTR
23 RST
22 TBRE
21 CO
20 RTS
19 DTR
18 DSR
17 CTS
16 GND
15 SDO
D6
D7
A0
9
10
11
12
A1
13
IX
82C52 (PLCC, CLCC)
TOP VIEW
CSO
WR
VCC
27
4
D2
D3
D4
D5
5
6
7
8
3
2
1
28
DR
26
25
24
23
22
21
20
19
SDI
INTR
RST
TBRE
RD
D0
CO
RTS
DTR
14
OX
15
SDO
16
GND
17
CTS
18
DSR
22
26
Block Diagram
3 - 10
D0-D7
DATA
BUS
BUFFER
UART
CONTROL AND
STATUS
REGISTERS
INTERNAL DATA BUS
TBRE
DR
RD
WR
A0
A1
CSO
IX
OX
CO
1
2
11
12
28
13
14
21
READ/WRITE
CONTROL
LOGIC
TRANSMITTER
BUFFER
REGISTER
TRANSMITTER
REGISTER
P
S
15
SDO
PROGRAM-
MABLE
BOUD RATE
GENERATOR
RST
INTR
23
24
CONTROL
LOGIC
RECEIVER
BUFFER
REGISTER
RECEIVER
REGISTER
P
S
25
SDI
18
MODEM
CONTROL AND
STATUS
REGISTERS
17
19
20
DSR
CTS
DTR
RTS
FN2950 Rev 4.00
November 25, 2015
Page 2 of 21
82C52
Pin Description
SYMBOL
RD
WR
D0-D7
PIN
NO.
1
2
3-10
TYPE
I
I
I/O
ACTIVE
LEVEL
Low
Low
High
DESCRIPTION
READ: The RD input causes the 82C52 to output data to the data bus (D0-D7). The data output
depends upon the state of the address inputs (A0-A1). CS0 enables the RD input.
WRITE: The WR input causes data from the data bus (D0-D7) to be input to the 82C52. Addressing
and chip select action is the same as for read operations.
DATA BITS 0-7: The Data Bus provides eight, three-state input/output lines for the transfer of data,
control and status information between the 82C52 and the CPU. For character formats of less than 8
bits, the corresponding D7, D6 and D5 are considered “don't cares” for data WRITE operations and
are 0 for data READ operations. These lines are normally in a high impedance state except during
read operations. D0 is the Least Significant Bit (LSB) and is the first serial data bit to be received or
transmitted.
ADDRESS INPUTS: The address lines select the various internal registers during CPU bus
operations.
CRYSTAL/CLOCK: Crystal connections for the internal Baud Rate Generator. IX can also be used
as an external clock input in which case OX should be left open.
High
SERIAL DATA OUTPUT: Serial data output from the 82C52 transmitter circuitry. A Mark (1) is a logic
one (high) and Space (0) is logic zero (low). SD0 is held in the Mark condition when CTS is false,
when RST is true, when the Transmitter Register is empty, or when in the Loop Mode.
GROUND: Power supply ground connection.
CLEAR TO SEND: The logical state of the CTS line is reflected in the CTS bit of the Modem Status
Register. Any change of state in CTS causes INTR to be set true when INTEN and MIEN are true. A
false level on CTS will inhibit transmission of data on the SD0 output and will hold SD0 in the Mark
(high) state. If CTS goes false during transmission, the current character being transmitted will be
completed. CTS does not affect Loop Mode operation.
DATA SET READY: The logical state of the DSR line is reflected in the Modem Status Register. Any
change of state of DSR will cause INTR to be set if INTEN and MIEN are true. The state of this signal
does not affect any other circuitry within the 82C52.
DATA TERMINAL READY: The DTR signal can be set (low) by writing a logic 1 to the appropriate bit
in the Modem Control Register (MCR). This signal is cleared (high) by writing a logic 0 in the DTR bit
in the MCR or whenever a reset (RST = high) is applied to the 82C52.
REQUEST TO SEND: The RTS signal can be set (low) by writing a logic 1 to the appropriate bit in
the MCR. This signal is cleared (high) by writing a logic 0 to the RTS bit in the MCR or whenever a
reset (RST = high) is applied to the 82C52.
CLOCK OUT: This output is user programmable to provide either a buffered IX output or a buffered
Baud Rate Generator (16X) clock output. The buffered IX (Crystal or external clock source) output is
provided when the Baud Rate Select Register (BRSR) bit 7 is set to a zero. Writing a logic one to
BRSR bit 7 causes the CO output to provide a buffered version of the internal Baud Rate Generator
clock which operates at sixteen times the programmed baud rate. On reset D7 (CO select) is reset to
0.
High
TRANSMITTER BUFFER REGISTER EMPTY: The TBRE output is set (high) whenever the
Transmitter Buffer Register (TBR) has transferred its data to the Transmit Register. Application of a
reset (RST) to the 82C52 will also set the TBRE output. TBRE is cleared (low) whenever data is
written to the TBR.
RESET: The RST input forces the 82C52 into an “Idle” mode in which all serial data activities are
suspended. The Modem Control Register (MCR) along with its associated outputs are cleared. The
UART Status Register (USR) is cleared except for the TBRE and TC bits, which are set. The 82C52
remains in an “Idle” state until programmed to resume serial data activities. The RST input is a
Schmitt triggered input.
INTERRUPT REQUEST: The INTR output is enabled by the INTEN bit in the Modem Control
Register (MCR). The MIEN bit selectively enables modem status changes to provide an input to the
INTR logic. Figure 9 in Design Information shows the overall relationship of these interrupt control
signals.
A0, A1
IX, OX
SDO
11, 12
13, 14
15
I
I/O
O
High
GND
CTS
16
17
I
Low
Low
DSR
18
I
Low
DTR
19
O
Low
RTS
20
O
Low
CO
21
O
TBRE
22
O
RST
23
I
High
INTR
24
O
High
FN2950 Rev 4.00
November 25, 2015
Page 3 of 21
82C52
Pin Description
SYMBOL
SDI
PIN
NO.
25
(Continued)
ACTIVE
LEVEL
High
DESCRIPTION
SERIAL DATA INPUT: Serial data input to the 82C52 receiver circuits. A Mark (1) is high, and a
Space (0) is low. Data inputs on SDI are disabled when operating in the loop mode or when RST is
true.
DATA READY: A true level indicates that a character has been received, transferred to the RBR, and
is ready for transfer to the CPU. DR is reset on a data READ of the Receiver Buffer Register (RBR)
or when RST is true.
V
CC
: +5V positive power supply pin. A 0.1F decoupling capacitor from V
CC
(Pin 27) to GND (Pin
16) is recommended.
CHIP SELECT: The chip select input acts as an enable signal for the RD and WR input signals.
TYPE
I
DR
26
O
High
V
CC
CS0
27
28
I
High
Low
FN2950 Rev 4.00
November 25, 2015
Page 4 of 21
82C52
Reset
During and after power-up, the 82C52 Reset Input (RST)
must be held high for at least two IX clock cycles in order to
initialize and drive the 82C52 circuits to an idle mode until
proper programming can be done. A high on RST causes
the following events to occur
• Resets the internal Baud Rate Generator (BRG) circuit
clock counters and bit counters. The Baud Rate Select
Register (BRSR) is not affected (except for bit 7 which is
reset to 0).
• Clears the UART Status Register (USR) except for
Transmission Complete (TC) and Transmit Buffer Register
Empty (TBRE) which are set. The Modem Control
Register (MCR) is also cleared. All of the discrete lines,
memory elements and miscellaneous logic associated
with these register bits are also cleared or turned off. Note
that the UART Control Register (UCR) is not affected.
Following removal of the reset condition (RST = low), the
82C52 remains in the idle mode until programmed to its
desired system configuration.
Programming The 82C52
The complete functional definition of the 82C52 is
programmed by the systems software. A set of control words
(UCR, BRSR and MCR) must be sent out by the CPU to
initialize the 82C52 to support the desired communication
format. These control words will program the character
length, number of stop bits, even/odd/no parity, baud rate,
etc. Once programmed, the 82C52 is ready to perform its
communication functions.
The control registers can be written to in any order. However,
the MCR should be written to last because it controls the
interrupt enables, modem control outputs and the receiver
enable bit. Once the 82C52 is programmed and operational,
these registers can be updated any time the 82C52 is not
immediately transmitting or receiving data.
Table 1. Shows the control signals required to access 82C52
internal registers.
UART Control Register (UCR)
The UCR is a write only register which configures the UART
transmitter and receiver circuits. Data bits D7 and D6 are not
used but should always be set to a logic zero (0) in order to
insure software compatibility with future product upgrades.
During the Echo Mode, the transmitter always repeats the
received word and parity, even when the UCR is
programmed with different or no parity. See Figure 1.
Word
Length
Select
TABLE 1.
CS0
0
0
0
0
0
0
0
0
A1
0
0
0
0
1
1
1
1
A0
0
0
1
1
0
0
1
1
WR
0
1
0
1
0
1
0
1
RD
1
0
1
0
1
0
1
0
OPERATION
Data Bus
Transmitter Buffer
Register (TBR)
Receiver Buffer Register
(RBR)
Data Bus
Data Bus
UART Control
Register (UCR)
UART Status Register
(USR)
Data Bus
Data Bus
Modem Control
Register (MCR)
MCR
Data Bus
Data Bus
Bit Rate Select
Register (BRSR)
Modem Status Register
(MSR)
Data Bus
D7 D6 D5 D4 D3 D2 D1 D0
Stop Bit
Select
0 = 1 Stop Bits
1 = 1.5 Stop Bits (Tx)
and 1 Stop Bit (Rx)
If 5 Data Bits Selected
1 = 2 Stop Bits for 6, 7
or 8 Data Bits Selected
000 = Tx and Rx Even
001 = Tx and Rx Odd
010 = Tx Even, Rx
Odd
011 = Tx Odd, Rx
Even
100 = Tx Even, Rx
Check Disabled
101 = Tx Odd, Rx
Check Disabled
11X = Generation and
Check Disabled
00 = 5 Bits
01 = 6 Bits
10 = 7 Bits
11 = 8 Bits
Parity
Control
Reserved Set to 00 for Future
Product Upgrade
Compatibility
FIGURE 1. UCR
Baud Rate Select Register (BRSR)
The 82C52 is designed to operate with a single crystal or
external clock driving the IX input pin. The Baud Rate Select
Register is used to select the divide ratio (one of 72) for the
internal Baud Rate Generator circuitry. The internal circuitry
is separated into two separate counters, a Prescaler and a
Divisor Select. The Prescaler can be set to any one of four
division rates,
1, 3, 4,
or
5.
FN2950 Rev 4.00
November 25, 2015
Page 5 of 21
