- 您现在的位置：买卖IC网 > PDF目录383110 > IP82C54-12 (HARRIS SEMICONDUCTOR) CMOS Programmable Interval Timer PDF资料下载
参数资料
| 型号： | IP82C54-12 |
| 厂商： | HARRIS SEMICONDUCTOR |
| 元件分类： | XO, clock |
| 英文描述： | CMOS Programmable Interval Timer |
| 中文描述： | 3 TIMER(S), PROGRAMMABLE TIMER, PDIP24 |
| 文件页数： | 4/17页 |
| 文件大小： | 142K |
| 代理商： | IP82C54-12 |
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 Con-
trol 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, con-
tains the current contents of the Control Word Register and
status of the output and null count flag. (See detailed expla-
nation 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 “fol-
low” 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 drive the inter-
nal bus. This is how the 16-bit Counter communicates over the
8-bit internal bus. Note that the CE itself cannot be read; when-
ever 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 simulta-
neously. CRM and CRL are cleared when the Counter is pro-
grammed 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
DATA/
BUS
BUFFER
I
OUT 2
GATE 2
CLK 2
OUT 1
GATE 1
CLK 1
OUT 0
GATE 0
CLK 0
WR
RD
D
7
- D
0
A
0
A
1
CS
FIGURE 2. CONTROL WORD REGISTER AND COUNTER
FUNCTIONS
8
CONTROL
WORD
REGISTER
COUNTER
2
COUNTER
1
COUNTER
0
INTERNAL BUS
CONTROL
LOGIC
CONTROL
WORD
REGISTER
STATUS
LATCH
STATUS
REGISTER
CLK n
GATE n
OUT n
OL
M
OL
L
CE
CR
M
CR
L
FIGURE 3. COUNTER INTERNAL BLOCK DIAGRAM
82C54
相关PDF资料 |
PDF描述 |
|---|---|
| IP82C54 | CMOS Programmable Interval Timer |
| IP82C54-10 | CMOS Programmable Interval Timer |
| IP82C59A | CMOS Priority Interrupt Controller |
| IP82C59A-5 | CMOS Priority Interrupt Controller |
| IP82C59A-12 | CMOS Priority Interrupt Controller |
相关代理商/技术参数 |
参数描述 |
|---|---|
| IP82C54Z | 功能描述:计时器和支持产品 W/ANNEAL PERIPH PRG- CNTR 5V 8MHZ RoHS:否 制造商:Micrel 类型:Standard 封装 / 箱体:SOT-23 内部定时器数量:1 电源电压-最大:18 V 电源电压-最小:2.7 V 最大功率耗散: 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装:Reel |
| IP82C55A | 功能描述:外围驱动器与原件 - PCI PERIPH PRG-I/O 5V 8MHZ IND RoHS:否 制造商:PLX Technology 工作电源电压: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:FCBGA-1156 封装:Tray |
| IP82C55A/+ | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Peripheral Interface |
| IP82C55A-5 | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| IP82C55AS2064 | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
发布紧急采购，3分钟左右您将得到回复。