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| 型號(hào)： | PSD301L |
| 英文描述： | Field Programmable Microcontroller Peripherals(可編程邏輯,16K位SRAM,19個(gè)可編程I/O,通用PLD有12個(gè)輸入) |
| 中文描述： | 現(xiàn)場(chǎng)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(gè)可編程輸入/輸出，通用PLD的有12個(gè)輸入） |
| 文件頁數(shù)： | 1/23頁 |
| 文件大?。?/td> | 118K |
| 代理商： | PSD301L |
3-19
Programmable Peripheral
Application Note 048
Designing with Flash Memory
By Dan Friedman – WSI
Introduction
Reason for
Using Flash
Memory
Methods of
Programming
Flash Memory has gained a wide popularity as a choice of use in embedded system
solutions. Many designers, who are using Microcontrollers, are using Flash Memory for
program store and sometimes also for data store. The ability to reprogram Flash Memory in
the system has allowed designers to change the program code in production or out in the
field without a large expense of doing so. What many designers are not aware of is the
complexity of designing with Flash Memory for In-System Programming (ISP). One
important point to remember when reprogramming Flash Memory: the programming
algorithm cannot be executed out of the same Flash Memory device that is being
programmed. It must be executed out of a separate memory device such as an EPROM or
SRAM device. At the time of this publication, there are no cost effective Flash Memory
devices that can perform this dual function. This Application Note will address the issues of
designing Flash Memory into a system and show an easy solution using WSI’s PSD device
as a Flash Support Chip (FSP). The next few sections discuss the design issues of using
Flash Memory. A summary of these issues are shown in Table 1.
The two main reasons why designers use Flash Memory is to have the ability to cost
effectively change the program code in the field, and to load the latest version of program
code into the system just prior to shipping the product. Other designers may also use
segmented Flash Memory to store variables or calibration data. Flash Memory is also
used in manufacturing for running test programs. This can help decrease the cost of
manufacturing a product.
The designer must determine the method of programming a Flash Memory the first time
and reprogramming the Flash Memory in-system after the first time. The technique of
performing these two functions may be very different.
The Flash Memory can be initially programmed by an EPROM programmer, or programmed
in the system using a Boot EPROM or ROM, or programmed in the system using a
Microcontroller with a JTAG Port. If the system boots up out of the boot sector of the Flash
Memory, this boot sector must be initially programmed either by an external EPROM
programmer prior to the Flash Memory being assembled on the board or by an MCU with a
JTAG Port. Since most low cost Microcontrollers do not have a JTAG Port, there is an
added cost of programming Flash Memory on an EPROM Programmer prior to being
assembled on the board.
When reprogramming the Flash Memory in-circuit, a serial port or JTAG port must be used.
If a serial port is used, the data is downloaded to SRAM prior to being programmed into the
Flash Memory. Next, the Microcontroller must execute the programming algorithms to
reprogram the Flash Memory with the data that was downloaded from the serial port. If the
system does not have a separate boot EPROM or ROM to execute the programming
algorithms, the programming algorithms must be copied from the boot sector of the Flash
Memory into the SRAM. The programming algorithms must then be executed from the
SRAM while programming the Flash Memory. A common mistake designers make is
thinking that they can execute the programming algorithms out of the same Flash Memory
they are trying to program.
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相關(guān)PDF資料 |
PDF描述 |
|---|---|
| PSD302R | Field Programmable Microcontroller Peripherals(可編程邏輯,無SRAM,19個(gè)可編程I/O,通用PLD有16個(gè)輸入) |
| PSD303L | Field Programmable Microcontroller Peripherals(可編程邏輯,16K位SRAM,19個(gè)可編程I/O,通用PLD有16個(gè)輸入) |
| PSD303 | Field Programmable Microcontroller Peripherals(可編程邏輯,16K位SRAM,19個(gè)可編程I/O,通用PLD有16個(gè)輸入) |
| PSD311L | Field Programmable Microcontroller Peripherals(可編程邏輯,16K位SRAM,19個(gè)可編程I/O,通用PLD有12個(gè)輸入) |
| PSD311 | Field Programmable Microcontroller Peripherals(可編程邏輯,16K位SRAM,19個(gè)可編程I/O,通用PLD有12個(gè)輸入) |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| PSD301L-15J | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Field-Programmable Peripheral |
| PSD301L-15JI | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Field-Programmable Peripheral |
| PSD301L-15LI | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Field-Programmable Peripheral |
| PSD301L-15LM | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Field-Programmable Peripheral |
| PSD301L-15U | 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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