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| 型號： | PSD303 |
| 英文描述： | Field Programmable Microcontroller Peripherals(可編程邏輯,16K位SRAM,19個可編程I/O,通用PLD有16個輸入) |
| 中文描述： | 現(xiàn)場可編程微控制器外圍設(shè)備（可編程邏輯，16K的位的SRAM，19余個可編程輸入/輸出，通用PLD的有16個輸入） |
| 文件頁數(shù)： | 1/6頁 |
| 文件大?。?/td> | 60K |
| 代理商： | PSD303 |
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Introduction
Typical laptop/notebook computers operating DOS or Windows have at least two micros on
their boards. One is obviously the 80X86 microprocessor and the other is usually an 8042
or 80C51/31. The 8042 (the original AT standard keyboard controller) or 80C51/31 may also
be called the SCP or System Control Processor because it usually handles much of the
system user interface including keyboard, mouse-trackball, external keyboard, and pen
input controls. In addition it provides the interface to both the PS2 and AT buses, and
because of power consumption concerns, the SCP also usually handles battery/power
management while controlling the backlight and contrast of the display.
Many designers of these control systems have chosen to turn away from the 8042 in favor
of the 80C51 for a few reasons. For example, it is more powerful, provides additional
memory capacity, has more I/O, and is much lower in power than the 8042. Using the
80C51, however, isn't always straightforward because most versions of the 80C51 don't
have the complete SCP 8042-type 80X86 interface necessary for these applications.
Therefore, there have usually been two options considered by hardware engineers.
The first option is to use a standard 80C51 and design an ASIC or discrete multi-chip
implementation of components which incorporate the 80X86 interface for the SCP along
with keyboard control, address decoding, etc.. The 80X86 interface requires a bidirectional
status latch and two directional data latches. In most cases, external memory consisting of
at least 8K bytes of EPROM and 1K byte of SRAM is also needed. In some cases, FLASH
EPROM is used, although until recently, it was associated mainly with the core 80X86
processor.
The second option is to use the 80C51SL-12 controller from Intel in conjunction with a
peripheral device from WSI's PSD3XX family. The 80C51SL-12 is a special version of the
80C51 which has been available for about 2 years, but used extensively in notebook
applications for only about 6 months. It includes the 8042-type 80X86 interface along with
keyboard control and other functions. The 80C51SL has 256 bytes of internal SRAM, has
many I/Os and is housed in a 100-pin PQFP package. For time-to-market reasons, most
versions of the 80C51SL are shipped "ROMless" and used with external EPROM.
Although the 80C51SL has many I/Os, many hardware designers still consider it lacking in
enough I/O resources. It only has 8 user pins and all the rest are dedicated to specific
functions. For instance, there is the standard bus interface, 2 auxiliary serial ports for
external keyboards and mouse, 24-pins dedicated to scanning the keyboard matrix, parallel
mailbox port on the AT bus, 4 analog inputs for A/D conversions, etc.
Programmable Peripheral
Application Note 026
PSD3XX Device Fit for PC Notebook
Applications: Keyboard, Power Management
and Auxiliary Peripherals Control
By Karen Spesard
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相關(guān)代理商/技術(shù)參數(shù) |
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| PSD303-12B | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Field-Programmable Peripheral |
| PSD303-12J | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Field-Programmable Peripheral |
| PSD303-12JI | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Field-Programmable Peripheral |
| PSD303-12LI | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Field-Programmable Peripheral |
| PSD303-12LM | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Field-Programmable Peripheral |
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