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參數(shù)資料
| 型號(hào)： | COP912C |
| 廠商： | National Semiconductor Corporation |
| 元件分類： | 8位微控制器 |
| 英文描述： | 8-Bit Microcontroller(8位微控制器) |
| 中文描述： | 8位微控制器（8位微控制器） |
| 文件頁數(shù)： | 7/20頁 |
| 文件大小： | 275K |
| 代理商： | COP912C |
Functional Description
(Continued)
SP
is the 8-bit stack pointer which points to the subroutine
stack (in RAM).
B, X and SP registers are mapped into the on chip RAM. The
B and X registers are used to address the on chip RAM. The
SP register is used to address the stack in RAM during sub-
routine calls and returns. The SP must be preset by software
upon initialization.
MEMORY
The memory is separated into two memory spaces: program
and data.
PROGRAM MEMORY
Program memory consists of 768 x 8 ROM. These bytes of
ROM may be instructions or constant data. The memory is
addressed by the 15-bit program counter (PC). There are no
“pages” of ROM, the PC counts all 15 bits. ROM can be in-
directly read by the LAlD instruction for table lookup.
DATA MEMORY
The data memory address space includes on chip RAM, I/O
and registers. Data memory is addressed directly by the in-
struction or indirectly through B, X and SP registers. The de-
vice has 64 bytes of RAM. Sixteen bytes of RAM are
mapped as “registers”, these can be loaded immediately,
decremented and tested. Three specific registers: X, B, and
SP are mapped into this space, the other registers are avail-
able for general usage.
Any bit of data memory can be directly set, reset or tested.
I/O and registers (except A and PC) are memory mapped;
therefore, I/O bits and register bits can be directly and indi-
vidually set, reset and tested.
RESET
The RESET input pin when pulled low initializes the micro-
controller. Upon initialization, the ports L and G are placed in
the TRl-STATE mode. The PC, PSW and CNTRL registers
are cleared. The data and configuration registers for ports L
and G are cleared. The external RC network shown in
Figure 3 should be used to ensure that the RESET pin is
held low until the power supply to the chip stabilizes.
OSCILLATOR CIRCUITS
The device can be driven by a clock input which can be be-
tween DC and 5 MHz.
CRYSTAL OSCILLATOR
By selecting CKO as a clock output, CKI and CKO can be
connected to create a crystal controlled oscillator. Table 1
shows the component values required for various standard
crystal values.
R/C OSCILLATOR
By selecting CKI as a single pin oscillator, CKI can make an
R/C oscillator. CKO is available as a general purpose input
and/or HALT control. Table 2shows variation in the oscillator
frequencies as functions of the component (R and C) value.
TABLE 1. Crystal Oscillator Configuration
R1
(k
)
R2
(m
)
C1
(pF)
C2
(pF)
CKI
Freq.
(MHz)
5
4
0.455
0
0
1
1
1
30
30
200
30–36
30–36
100–150
5.6
TABLE 2. RC Oscillator Configuration
(Part-to-Part Variation, T
A
= 25C)
R
(k
)
C
(pF)
CKI Freq.
(MHz)
Intr.
Cycle
(μs)
3.7 to 4.6
7.4 to 9
8.8 to 10.8
3.3
5.6
6.8
82
100
100
2.2 to 2.7
1.1 to 1.3
0.9 to 1.1
Note 5:
3k
≤
R
≤
200 k
, 50 pF
≤
C
≤
200 pF.
HALT MODE
The device is a fully static device. The device enters the
HALT mode by writing a one to the G7 bit of the G data reg-
ister. Once in the HALT mode, the internal circuitry does not
receive any clock signal and is therefore frozen in the exact
state it was in when halted. In this mode the chip will only
draw leakage current.
The device supports two different ways of exiting the HALT
mode. The first method is with a low to high transition on the
CKO (G7) pin. This method precludes the use of the crystal
clock configuration (since CKO is a dedicated output), and
so may be used either with an RC clock configuration (or an
external clock configuration). The second method of exiting
the HALT mode is to pull the RESET low.
Note:
To allow clock resynchronization, it is necessary to program two NOP’s
immediately after the device comes out of the HALT mode. The user
must program two NOP’s following the “enter HALT mode” (set G7
data bit) instruction.
MICROWIRE/PLUS
MICROWIRE/PLUS is a serial synchronous communications
interface. The MICROWIRE/PLUS capability enables the de-
vice to interface with any of National Semiconductor’s
MICROWIRE peripherals (i.e., A/D converters, display driv-
DS012060-5
RC
>
5 x POWER SUPPLY RISE TIME
FIGURE 3. Recommended Reset Circuit
DS012060-6
FIGURE 4. Clock Oscillator Configurations
C
www.national.com
7
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| COP912CH | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:8-Bit Microcontroller |
| COP912CH-XXX/N | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:8-Bit Microcontroller |
| COP912CH-XXX/WM | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:8-Bit Microcontroller |
| COP912C-XXX/N | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:8-Bit Microcontroller |
| COP912C-XXX/WM | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:8-Bit Microcontroller |
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