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參數(shù)資料
| 型號(hào)： | uPSD3234 |
| 廠商： | 意法半導(dǎo)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(yè)數(shù)： | 26/54頁(yè) |
| 文件大?。?/td> | 736K |
| 代理商： | UPSD3234 |
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AN1886 - APPLICATION NOTE
26/54
Figure 6. Traffic on USB (μPSD32xxA connected to an NEC 720100A Type USB 2.0 Host)
It follows that the time constraints on the USB device are much tighter for High-speed USB 2.0 hosts, as
opposed to those for old USB 1.1 hosts (where the USB device has plenty of time to complete the previous
USB interrupt service routine, and all the tasks connected with the previous request, and the internal USB
state machine inside the USB device is not influenced by changes or communication on USB bus).
USB Interrupt must have the Highest Priority Interrupt Level
It is strongly recommended to assign the highest priority level
only
to the USB, to minimize the latency to
USB interrupt requests. In particular, the USB block of the μPSD32xxA has a small FIFO and no overflow
flags, so all the USB servicing routines must be executed as soon as possible, for proper message han-
dling.
In the μPSD32xxA, each interrupt source can be assigned one of two priority levels. Interrupt priority levels
are defined by the appropriate bit in the interrupt priority special function register, IP and IPA:
0 = low priority
1 = high priority
A low priority interrupt may be interrupted by a high priority one. A high priority interrupt routine cannot be
interrupted by any other. If two interrupts of different priority occur simultaneously, the high priority level
request is serviced. If requests of the same priority are received simultaneously, an internal polling se-
quence determines which request is serviced. Thus, within each priority level, there is a second priority
structure determined by the polling sequence.
The optimal arrangement can be achieved by the following initialization:
■
■
IP = 0; // USB must have the highest priority!
IPA = 1; // USB must have the highest priority!
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相關(guān)代理商/技術(shù)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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