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參數(shù)資料
| 型號： | PSD301L |
| 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12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12個輸入） |
| 文件頁數(shù)： | 2/23頁 |
| 文件大?。?/td> | 118K |
| 代理商： | PSD301L |
3-20
Flash Memory – Application Note 048
Methods of
Programming
(cont.)
Manufacturing
Stages of
Programming
System
Programming
Issues
If a JTAG port is available on the MCU, this port can be used to reprogram the Flash
Memory in the same manner as programming the Flash Memory the first time. The boot
code can be downloaded through the JTAG port into local SRAM inside the Microcontroller
while the Microcontroller is being held in reset. The boundary scan registers on the
Microcontroller can also be used to program the Flash Memory in-circuit. Since most low
cost Microcontrollers do not have a JTAG Port, further discussions in this application note
will assume that a JTAG Port is not available.
Flash Memory can be programmed in various stages of the manufacturing process. If no
boot EPROM or ROM is used in the system, the Flash Memory must be programmed on an
EPROM Programmer prior to being assembled onto the board. As a minimum, the boot
sector must be programmed at this time. Manufacturing personnel must be careful not to
assemble the wrong programmed part on the board. This mistake may be costly as it will be
detected in Functional Test where test time and troubleshooting is expensive. The program
code may also change prior to shipping the product. If this occurs, programming at this
stage will be an unnecessary cost added to manufacturing. During in-circuit test, test code
may be loaded into Flash Memory. This may simplify the testability of the system.
Functional Test is the most expensive stage for detecting a bad or incorrectly programmed
Flash Memory. From a manufacturing point of view, the least expensive Flash solution is
having the ability to assemble a blank Flash Memory device on the board and program it
during the in-circuit test phase. This requires a separate boot EPROM or ROM.
There are various system programming issues that must be considered when designing
Flash Memory systems. The most important issue was stated previously: the system
cannot execute the programming algorithms from the same Flash Memory being
programmed. Some designers will store the programming algorithms in the boot sector of
the Flash Memory. When programming the Flash Memory, the system must copy the
algorithms from Flash to SRAM. The system will next execute the algorithms from SRAM to
program the Flash Memory.
Taking a closer look at what is involved in doing this, I will use an 80C31 for an example.
The 80C31 has a separate Program Space and Data Space. Initially the Flash Memory is in
the Program Space and the SRAM is in the Data Space. To copy the algorithms from Flash
Memory to SRAM, the Flash Memory and SRAM must be in the Data Space. The code
executing in the Flash Memory to copy the algorithms must be in the Program Space. Once
the algorithms are in the SRAM, the SRAM must be moved to the Program Space while the
Flash Memory remains in the Data Space. To work around this problem, both the Flash
Memory and SRAM must be in both the Program and Data Space at the same time. This
can be a problem if the sum of memory sizes of the Flash Memory, SRAM, and other I/O
functions exceeds the 64 Kbytes of address space. The solution to this problem requires a
lot of PLD logic for address decoding in both the Operational and Programming Modes
along with a page register to extend the addressing capabilities of the 80C31 in the
Programming Mode.
There are other concerns the designer must consider. What if power fails while the
Microcontroller is executing the programming algorithm from SRAM The programming
state machine built into Flash Memories must reset itself and allow access to the boot
sector when powering the system back up. The system then must have the ability to
reprogram the corrupted Flash Memory. The boot block in the system must be write
protected. If this boot block is corrupted for any reason, the system will be inoperative. The
best protection for the boot block and programming algorithms is to store them in EPROM
or ROM technology. If there is a way to reprogram the boot block, there is a way to corrupt
it. Some sector protect techniques cannot guarantee that the sector will not be corrupted
when the Microcontroller malfunctions and executes the wrong code (maybe unlocking and
corrupting a sector).
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| PSD302R | Field Programmable Microcontroller Peripherals(可編程邏輯,無SRAM,19個可編程I/O,通用PLD有16個輸入) |
| PSD303L | 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) |
| PSD303 | 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) |
| PSD311L | Field Programmable Microcontroller Peripherals(可編程邏輯,16K位SRAM,19個可編程I/O,通用PLD有12個輸入) |
| PSD311 | Field Programmable Microcontroller Peripherals(可編程邏輯,16K位SRAM,19個可編程I/O,通用PLD有12個輸入) |
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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