Harris Semiconductor IP82C54-12, IP82C54-10 Datasheet

4-1

Semiconductor

March 1997

82C54

CMOS Programmable Interval Timer

Features

• 8MHz to 12MHz Clock Input Frequency

• Compatible with NMOS 8254

- Enhanced Version of NMOS 8253

• Three Independent 16-Bit Counters

• Six Programmable Counter Modes

• Status Read Back Command

• Binary or BCD Counting

• Fully TTL Compatible

• Single 5V Power Supply

• Low Power

- ICCSB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10µA

- ICCOP . . . . . . . . . . . . . . . . . . . . . . . . . .10mA at 8MHz

• Operating Temperature Ranges

- C82C54 . . . . . . . . . . . . . . . . . . . . . . . . . .0

C to +70oC

- I82C54 . . . . . . . . . . . . . . . . . . . . . . . . . -40

C to +85oC

- M82C54 . . . . . . . . . . . . . . . . . . . . . . . -55

C to +125oC

Description

The Harris 82C54 is a high performance CMOS Programmable Interval Timer manufactured using an adv anced 2 micron CMOS process.

The 82C54 has three independently programmable and functional 16-bit counters, each capable of handling clock input frequencies of up to 8MHz (82C54) or 10MHz (82C54-10) or 12MHz (82C54-12).

The high speed and industry standard conﬁguration of the 82C54 make it compatible with the Harris 80C86, 80C88, and 80C286 CMOS microprocessors along with many other industry standard processors. Six programmable timer modes allow the 82C54 to be used as an event counter, elapsed time indicator, programmable one-shot, and many other applications. Static CMOS circuit design insures low power operation.

The Harris advanced CMOS process results in a signiﬁcant reduction in power with performance equal to or greater than existing equivalent products.

Pinouts

82C54 (PDIP, CERDIP, SOIC)

TOP VIEW

82C54 (PLCC/CLCC)

TOP VIEW

1 2 3 4 5 6 7 8

9 10 11 12

15 14 13

D7 D6 D5 D4 D3 D2 D1

D0 CLK 0 OUT 0

GATE 0

GND

VCC

RD CS A1 A0

OUT 2

CLK 1 GATE 1 OUT 1

CLK 2

GATE 2

GND

OUT 1

GATE 1

CLK 1

OUT 0

GATE 0

VCC

CS A1 A0 CLK2

GATE 2

OUT 2

1234

5 6 7 8

9 10 11

12 13 14 15 16 17 18

262728

D3 D2 D1 D0

CLK 0

CAUTION: These devices are sensitive to electrostatic discharge. Users should follow proper IC Handling Procedures. Copyright

File Number 2970.1

4-2

Functional Diagram

Ordering Information

PART NUMBERS

TEMPERATURE

RANGE PACKAGE PKG. NO.8MHz 10MHz 12MHz

CP82C54 CP82C54-10 CP82C54-12 0oC to +70oC 24 Lead PDIP E24.6 IP82C54 IP82C54-10 IP82C54-12 -40oC to +85oC 24 Lead PDIP E24.6 CS82C54 CS82C54-10 CS82C54-12 0oC to +70oC 28 Lead PLCC N28.45 IS82C54 IS82C54-10 IS82C54-12 -40oC to +85oC 28 Lead PLCC N28.45 CD82C54 CD82C54-10 CD82C54-12 0oC to +70oC 24 Lead CERDIP F24.6 ID82C54 ID82C54-10 ID82C54-12 -40oC to +85oC 24 Lead CERDIP F24.6 MD82C54/B MD82C54-10/B MD82C54-12/B -55oC to +125oC 24 Lead CERDIP F24.6 MR82C54/B MR82C54-10/B MR82C54-12/B -55oC to +125oC 28 Lead CLCC J28.A SMD # 8406501JA - 8406502JA -55oC to +125oC 24 Lead CERDIP F24.6 SMD# 84065013A - 84065023A -55oC to +125oC 28 Lead CLCC J28.A CM82C54 CM82C54-10 CM82C54-12 0oC to +70oC 24 Lead SOIC M24.3

Pin Description

SYMBOL

DIP PIN

NUMBER TYPE DEFINITION

D7 - D0 1 - 8 I/O DATA: Bi-directional three-state data bus lines, connected to system data bus.

CLK 0 9 I CLOCK 0: Clock input of Counter 0. OUT 0 10 O OUT 0: Output of Counter 0.

GATE 0 11 I GATE 0: Gate input of Counter 0.

GND 12 GROUND: Power supply connection.

OUT 1 13 O OUT 1: Output of Counter 1.

GATE 1 14 I GATE 1: Gate input of Counter 1.

CLK 1 15 I CLOCK 1: Clock input of Counter 1.

GATE 2 16 I GATE 2: Gate input of Counter 2.

OUT 2 17 O OUT 2: Output of Counter 2.

CONTROL

WORD

READ/ WRITE LOGIC

DAT A/

BUS

BUFFER

COUNTER

INTERNAL BUS

CONTROL

LOGIC

CONTROL

WORD

STATUS

LATCH

STATUS

CLK n

GATE n

OUT n

OUT 2

GATE 2

CLK 2

OUT 1

GATE 1

CLK 1

OUT 0

GATE 0

CLK 0

- D

COUNTER INTERNAL BLOCK DIAGRAM

82C54

4-3

Functional Description

General

The 82C54 is a programmable interval timer/counter designed for use with microcomputer systems. It is a general purpose, multi-timing element that can be treated as an array of I/O ports in the system software.

The 82C54 solves one of the most common problems in any microcomputer system, the generation of accurate time delays under software control. Instead of setting up timing loops in software, the programmer conﬁgures the 82C54 to match his requirements and programs one of the counters for the desired delay. After the desired delay, the 82C54 will interrupt the CPU. Software overhead is minimal and variable length delays can easily be accommodated.

Some of the other computer/timer functions common to microcomputers which can be implemented with the 82C54 are:

• Real time clock

• Event counter

• Digital one-shot

• Programmable rate generator

• Square wave generator

• Binary rate multiplier

• Complex waveform generator

• Complex motor controller

Data Bus Buffer

This three-state, bi-directional, 8-bit buffer is used to interface the 82C54 to the system bus (see Figure 1).

Read/Write Logic

The Read/Write Logic accepts inputs from the system bus and generates control signals for the other functional blocks of the 82C54. A1 and A0 select one of the three counters or the Control Word Register to be read from/written into. A “low” on the RD input tells the 82C54 that the CPU is reading one of the counters. A “low” on the

WR input tells the 82C54 that the CPU

is writing either a Control Word or an initial count. Both

RD and WR are qualiﬁed by CS; RD and WR are ignored unless the 82C54 has been selected by holding

CS low.

CLK 2 18 I CLOCK 2: Clock input of Counter 2.

A0, A1 19 - 20 I ADDRESS: Select inputs for one of the three counters or Control Word Register for read/write

operations. Normally connected to the system address bus.

CS 21 I CHIP SELECT: A low on this input enables the 82C54 to respond to RD and WR signals. RD and

WR are ignored otherwise. RD 22 I READ: This input is low during CPU read operations. WR 23 I WRITE: This input is low during CPU write operations.

24 VCC: The +5V power supply pin. A 0.1µF capacitor between pins VCC and GND is recommended

for decoupling.

Pin Description

(Continued)

SYMBOL

DIP PIN

NUMBER TYPE DEFINITION

A1 A0 SELECTS

0 0 Counter 0 0 1 Counter 1 1 0 Counter 2 1 1 Control Word Register

CONTROL

WORD

COUNTER

INTERNAL BUS

OUT 2

GATE 2

CLK 2

OUT 1

GATE 1

CLK 1

OUT 0

GATE 0

CLK 0

- D

FIGURE 1. DATA BUS BUFFER AND READ/WRITE LOGIC

FUNCTIONS

DAT A/

BUS

BUFFER

READ/ WRITE LOGIC

82C54

4-4

Control Word Register

The Control Word Register (Figure 2) is selected by the Read/Write Logic when A1, A0 = 11. If the CPU then does a write operation to the 82C54, the data is stored in the Control Word Register and is interpreted as a Control Word used to deﬁne the Counter operation.

The Control Word Register can only be written to; status information is available with the Read-Back Command.

Counter 0, Counter 1, Counter 2

These three functional blocks are identical in operation, so only a single Counter will be described. The internal block diagram of a signal counter is shown in Figure 3. The counters are fully independent. Each Counter may operate in a different Mode.

The Control Word Register is shown in the ﬁgure; it is not part of the Counter itself, but its contents determine how the Counter operates.

The status register, shown in the ﬁgure, when latched, contains the current contents of the Control Word Register and status of the output and null count ﬂag. (See detailed explanation of the Read-Back command.)

The actual counter is labeled CE (for Counting Element). It is a 16-bit presettable synchronous down counter.

OLM and OLL are two 8-bit latches. OL stands for “Output Latch”; the subscripts M and L for “Most signiﬁcant byte” and “Least signiﬁcant byte”, respectively. Both are normally referred to as one unit and called just OL. These latches normally “follow” the CE, but if a suitable Counter Latch Command is sent to the 82C54, the latches “latch” the present count until read by the CPU and then return to “following” the CE. One latch at a time is enabled by the counter’ s Control Logic to driv e the internal bus. This is how the 16-bit Counter communicates over the 8-bit internal bus. Note that the CE itself cannot be read; whenever you read the count, it is the OL that is being read.

Similarly, there are two 8-bit registers called CRM and CRL (for “Count Register”). Both are normally referred to as one unit and called just CR. When a new count is written to the Counter, the count is stored in the CR and later transferred to the CE. The Control Logic allows one register at a time to be loaded from the internal bus. Both bytes are transferred to the CE simultaneously. CRM and CRL are cleared when the Counter is programmed for one byte counts (either most signiﬁcant byte only or least signiﬁcant byte only) the other byte will be zero. Note that the CE cannot be written into; whenever a count is written, it is written into the CR.

The Control Logic is also shown in the diagram. CLK n, GATE n, and OUT n are all connected to the outside world through the Control Logic.

82C54 System Interface

The 82C54 is treated by the system software as an array of peripheral I/O ports; three are counters and the fourth is a control register for MODE programming.

Basically, the select inputs A0, A1 connect to the A0, A1 address bus signals of the CPU. The

CS can be derived directly from the address bus using a linear select method or it can be connected to the output of a decoder.

READ/ WRITE LOGIC

DAT A/

BUS

BUFFER

INTERNAL BUS

OUT 2

GATE 2

CLK 2

OUT 1

GATE 1

CLK 1

OUT 0

GATE 0

CLK 0

- D

FIGURE 2. CONTROL WORD REGISTER AND COUNTER

FUNCTIONS

CONTROL

WORD

COUNTER

INTERNAL BUS

CONTROL

LOGIC

CONTROL

WORD

STATUS

LATCH

STATUS

CLK n

GATE n

OUT n

FIGURE 3. COUNTER INTERNAL BLOCK DIAGRAM

82C54

4-5

Operational Description

General

After power-up, the state of the 82C54 is undeﬁned. The Mode, count value, and output of all Counters are undeﬁned.

How each Counter operates is determined when it is programmed. Each Counter must be programmed before it can be used. Unused counters need not be programmed.

Programming the 82C54

Counters are programmed by writing a Control Word and then an initial count.

All Control Words are written into the Control Word Register, which is selected when A1, A0 = 11. The Control Word speciﬁes which Counter is being programmed.

By contrast, initial counts are written into the Counters, not the Control Word Register. The A1, A0 inputs are used to select the Counter to be written into. The format of the initial count is determined by the Control Word used.

FIGURE 4. 82C54 SYSTEM INTERFACE

Write Operations

The programming procedure for the 82C54 is very ﬂexible. Only two conventions need to be remembered:

1.For Each Counter, the Control Word must be written before the initial count is written.

2.The initial count must follow the count format speciﬁed in the Control Word (least signiﬁcant byte only, most signiﬁcant byte only, or least signiﬁcant byte and then most signiﬁcant byte).

Since the Control Word Register and the three Counters have separate addresses (selected by the A1, A0 inputs), and each Control Word speciﬁes the Counter it applies to (SC0, SC1 bits), no special instruction sequence is required. Any programming sequence that follows the con v entions abo v e is acceptab le .

Control Word Format

A1, A0 = 11;

CS = 0; RD = 1; WR = 0

D7 D6 D5 D4 D3 D2 D1 D0

SC1 SC0 RW1 RW0 M2 M1 M0 BCD

ADDRESS BUS (16)

CONTROL BUS

DATA BUS (8)

I/OR I/OW

A1 A0

COUNTER

OUTGATECLK

COUNTER

OUTGATECLK OUTGATECLK

D0 - D7

82C54

SC - Select Counter

SC1 SC0

0 0 Select Counter 0 0 1 Select Counter 1 1 0 Select Counter 2 1 1 Read-Back Command (See Read Operations)

RW - Read/Write

RW1 RW0

0 0 Counter Latch Command (See Read Operations) 0 1 Read/Write least significant byte only. 1 0 Read/Write most significant byte only. 1 1 Read/Write least significant byte first, then most

significant byte.

M - Mode

M2 M1 M0

0 0 0 Mode 0

0 0 1 Mode 1 X 1 0 Mode 2 X 1 1 Mode 3

1 0 0 Mode 4

1 0 1 Mode 5

BCD - Binary Coded Decimal

0 Binary Counter 16-bit 1 Binary Coded Decimal (BCD) Counter (4 Decades)

NOTE: Don’t Care bits (X) should be 0 to insure compatibility with

future products.

Possible Programming Sequence

A1 A0

Control Word - Counter 0 1 1 LSB of Count - Counter 0 0 0 MSB of Count - Counter 0 0 0 Control Word - Counter 1 1 1 LSB of Count - Counter 1 0 1 MSB of Count - Counter 1 0 1 Control Word - Counter 2 1 1 LSB of Count - Counter 2 1 0 MSB of Count - Counter 2 1 0

Possible Programming Sequence

A1 A0

Control Word - Counter 0 1 1 Control Word - Counter 1 1 1 Control Word - Counter 2 1 1 LSB of Count - Counter 2 1 0

82C54

4-6

A new initial count may be written to a Counter at any time without affecting the Counter’s programmed Mode in any way. Counting will be affected as described in the Mode deﬁnitions. The new count must follow the prog r ammed count format.

If a Counter is programmed to read/write two-byte counts, the following precaution applies. A progr am must not tr ansf er control between writing the ﬁrst and second byte to another routine which also writes into that same Counter. Otherwise, the Counter will be loaded with an incorrect count.

Read Operations

It is often desirable to read the value of a Counter without disturbing the count in progress. This is easily done in the 82C54.

There are three possible methods for reading the Counters. The ﬁrst is through the Read-Back command, which is

explained later . The second is a simple read operation of the Counter, which is selected with the A1, A0 inputs. The only requirement is that the CLK input of the selected Counter must be inhibited by using either the GATE input or external logic. Otherwise, the count may be in process of changing when it is read, giving an undeﬁned result.

Counter Latch Command

The other method for reading the Counters involves a special software command called the “Counter Latch Command”. Like a Control Word, this command is written to the Control Word Register, which is selected when A1, A0 = 11. Also, like a Control Word, the SC0, SC1 bits select one of the three Counters, but two other bits, D5 and D4, distinguish this command from a Control Word.

The selected Counter’s output latch (OL) latches the count when the Counter Latch Command is received. This count is held in the latch until it is read by the CPU (or until the Counter is reprogrammed). The count is then unlatched automatically and the OL returns to “following” the counting element (CE). This allows reading the contents of the Counters “on the ﬂy” without affecting counting in progress. Multiple Counter Latch Commands may be used to latch more than one Counter. Each latched Counter’s OL holds its count until read. Counter Latch Commands do not affect the programmed Mode of the Counter in any way.

If a Counter is latched and then, some time later, latched again before the count is read, the second Counter Latch Command is ignored. The count read will be the count at the time the ﬁrst Counter Latch Command was issued.

With either method, the count must be read according to the programmed format; speciﬁcally, if the Counter is programmed for two byte counts, two bytes must be read. The two bytes do not have to be read one right after the other ; read or write or programming operations of other Counters may be inserted between them.

Another feature of the 82C54 is that reads and writes of the same Counter may be interleaved; for example, if the Counter is programmed for two byte counts, the following sequence is valid.

LSB of Count - Counter 1 0 1 LSB of Count - Counter 0 0 0 MSB of Count - Counter 0 0 0 MSB of Count - Counter 1 0 1 MSB of Count - Counter 2 1 0

Possible Programming Sequence

A1 A0

Control Word - Counter 2 1 1 Control Word - Counter 1 1 1 Control Word - Counter 0 1 1 LSB of Count - Counter 2 1 0 MSB of Count - Counter 2 1 0 LSB of Count - Counter 1 0 1 MSB of Count - Counter 1 0 1 LSB of Count - Counter 0 0 0 MSB of Count - Counter 0 0 0

Possible Programming Sequence

A1 A0

Control Word - Counter 1 1 1 Control Word - Counter 0 1 1 LSB of Count - Counter 1 0 1 Control Word - Counter 2 1 1 LSB of Count - Counter 0 0 0 MSB of Count - Counter 1 0 1 LSB of Count - Counter 2 1 0 MSB of Count - Counter 0 0 0 MSB of Count - Counter 2 1 0

NOTE: In all four examples, all counters are programmed to

Read/Write two-byte counts. These are only four of many programming sequences.

Possible Programming Sequence (Continued)

A1 A0

A1, A0 = 11; CS = 0; RD = 1; WR = 0

D7 D6 D5 D4 D3 D2 D1 D0

SC1SC000XXXX

SC1, SC0 - specify counter to be latched

SC1 SC0 COUNTER

00 0 01 1 10 2 1 1 Read-Back Command

D5, D4 - 00 designates Counter Latch Command, X - Don’t Care. NOTE: Don’t Care bits (X) should be 0 to insure compatibility with

future products.

82C54

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