UM8253 Datasheet PDF - UMC
Part Number | UM8253 | |
Description | Programmable Interval Timer | |
Manufacturers | UMC | |
Logo | ||
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UM8253/ UM8253-5
Features
• MCS-85™ compatible UM8253-5
• 3 independent 16-bit counters
• DC to 2.6 MHz
• Programmable counter modes
• Count binary or BCD
• Single +5V supply
General Description
The UM8253 is a programmable counter timer device
designed for use as an microcomputer peripheral. It uses
NMOS technology with a single +5V supply and is packaged
in a 24-pin plastic DIP.
It is organized as 3 independent 16-bit counters, each with
a count rate of up to 2.6 MHz. All modes of operation
are software programmable.
*MCS-85™ is the trademark of Intel microsystem.
Pin Configuration
Block Diagram
07
06
Os
04
03
O2
0,
00
ClK 0
OUT 0
GATE 0
GNO
VCC
WR
RO
CS
Al
Ao
ClK 2
OUT.2
GATE 2
ClK 1
GATE 1
OUT 1
.07-00
Ao
AI
Cs
READ/
WRITE
LOGIC
7-143
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Functional Description
General
The UM8253 is a programmable interval timer/counter
specifically designed for use with microcomputer systems.
Its function is that of a general purpose, multiming element
that can be treated as an array of I/O ports in the system
software.
The UM8253 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 systems software, the programmer
configures the UM8253 to match his requirements, initializes
one of the counters of the UM8253 with the desired
quantity, then upon command the UM8253 will count out
the delay and interrupt the UPU when it has completed its
tasks. It is easy to see that the software overhead is
minimal and that multiple delays can easily be maintained
by assignment of priority levels.
Other counterltimer functions that are non-delay in nature
but also common to most microcomputers can be
implemented with the UM8253.
• Programmable Rate Generator
• Event Counter
• Binary Rate Multiplier
• Real Time Clock
• Digital One-Shot
• Complex Motor Controller
UMS253 / UMS253-5
WR (Write)
A "low" on this input informs the UM8253 that the CPU
is outputting data in the form of mode information or
loading counters.
Ao ,Al
These inputs are normally connected to the address bus.
Their function is to select one of the three counters to be
operated on and to address the control word register for
mode selection.
Data Bus Buffer
This 3-state, bi-directional, 8-bit buffer is used to interface
the UM8253 to the system data bus. Data is transmitted
or received by the buffer upon execution of input or OUT
put CPU instructions. The Data Bus Buffer has three basic
functions.
1. Programming the MODES of the UM8253.
2. Loading the count registers.
3. Reading the count values.
Read/Write Logic
The Read/Write Logic accepts inputs from the system bus
and in turn generates control signals for overall device
operation. It is enable or disabled by CS so that no
operation can occur to change the function unless the
device has been selected by the system logic.
RD (Read)
A "low" on this input informs the UM8253 that the
CPU is inputting data in the form of a counters value.
Figure 1..Block Diagram Showing Data Bus Buffer and
Read/Write Logic Functions
CS RD
01
01
01
01
00
00
00
00
1X
01
WR Al
00
00
01
01
10
10
11
11
XX
1X
Ao
0
1
0
1
0
1
0
1
X
X
Load Cou nter No. 0
Load Counter NO.1
Load Counter No.2
Write Mode Word
Read Counter No. 0
Read Counter No.1
Read Counter Nb. 2
No-Operation 3-State
Disable 3-State
No-Operation 3-State
7-147
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Part DetailsOn this page, you can learn information such as the schematic, equivalent, pinout, replacement, circuit, and manual for UM8253 electronic component. |
Information | Total 11 Pages | |
Link URL | [ Copy URL to Clipboard ] | |
Download | [ UM8253.PDF Datasheet ] |
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