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參數(shù)資料
| 型號： | uPSD3234 |
| 廠商： | 意法半導體 |
| 英文描述： | Flash Programmable System Device with 8032 Microcontroller Core(嵌入高速“8032微控制器核”的Flash型可編程系統(tǒng)器) |
| 中文描述： | 閃存可編程系統(tǒng)器件與8032微控制器內(nèi)核（嵌入高速“8032微控制器核”的閃存型可編程系統(tǒng)器） |
| 文件頁數(shù)： | 32/54頁 |
| 文件大?。?/td> | 736K |
| 代理商： | UPSD3234 |
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AN1886 - APPLICATION NOTE
32/54
One correct solution is:
XRL UCON0,#0x80 ;toggle TSEQ bit
ANL UCON0,#(uTSEQ0+uRX0E) ;mask
MOV A,nBytes
ORL UCON0,A
Besides the fact that this solution is shorter, all the operational steps are executed independently in one
instruction. The μPSD hardware and software can change the contents of the register with the correct re-
sult.
All the versions of the USB demonstration program, since version 2.0_RP (December 2003), uses the new
construction directly written in the assembler language. The final code will have its proper content without
dependence on compiler settings, etc.
Note: Use any other constructions and C language only once you are sure about the real assembler out-
put.
Question: So How Must I Write My Drivers
One of the most important points is that all program steps that influence the USB part must be done in one
step, by
only
one instruction if possible. Keep in mind that the hardware can change some of the “bidirec-
tional” bits in USB register between the steps when a register is read, updated and written back. The last
step overwrites the new state of the register changed by the hardware.
In assembler, only use MOV, ORL, ANL or XRL instructions. In the C language, use constructions like:
UCON0 &= uRXE0;
UCON0 |= uSTALL0;
… etc.
Do not use more than one instruction (step) on one program line, because the compiler might optimize it
with uncertain results.
Note: Use any other constructions and C language only once you are sure about the real assembler out-
put.
Question: Must I Enable and Service End-of-Packet Interrupt Requests
No, End of Packet (EOP) interrupts can be disabled. EOP interrupts are used only for some very special
purposes. They can be generated as frequently as every tens of μs, result in increasing the CPU load.
Note: Do not use USB drivers or a USB demonstration program fully based on version 1.0.7E. This version
causes a very high CPU load because the USB interrupt is serviced on every EOP interrupt request even
where the previous invoking packet is not significant for processing by the software driver.
Question: Is the Length of USB ISR Limited
Yes, the length of USB interrupt service is limited. The limits are especially given by the USB specifications
on drivers used in hosts.
Limits Set by the Specification:.
Generally, the USB standards talk about very long time limits.
Table
25.
gives some examples.
Table 25. Examples of Limits set by USB Standards
Parameter
Limit
SetAddress() Completion Time
50ms
Time to complete standard request with no data
50ms
Time to deliver last data for standard request
50ms
相關PDF資料 |
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|---|---|
| uPSD3251(中文) | Flash Programmable System Devices with 8032 Microcontroller Core(帶8032微控制器內(nèi)核的Flash可編程系統(tǒng)設備) |
| uPSD3251 | Flash Programmable System Devices with 8032 Microcontroller Core(帶8032微控制器內(nèi)核的Flash可編程系統(tǒng)設備) |
| uPSD3253AV-24T1T | Flash Programmable System Devices with 8032 Microcontroller Core |
| UPSD3253B | Two and Three Channel Codewheels |
| UPSD3253BV | Flash Programmable System Devices with 8032 Microcontroller Core |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| UPSD32348V24V6ES | 制造商:ST MICRO 功能描述:* |
| UPSD3234A | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:Flash Programmable System Devices with 8032 Microcontroller Core |
| UPSD3234A-24T1 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:Flash Programmable System Device with 8032 Microcontroller Core |
| UPSD3234A-24T1T | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:Flash Programmable System Devices with 8032 Microcontroller Core and 64Kbit SRAM |
| UPSD3234A-24T6 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:Flash Programmable System Device with 8032 Microcontroller Core |
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