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參數(shù)資料
| 型號： | 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） |
| 文件頁數(shù)： | 28/54頁 |
| 文件大小： | 736K |
| 代理商： | UPSD3234 |
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AN1886 - APPLICATION NOTE
28/54
Length of USB Interrupt Service Routine
Based on performed tests and measurements, the worst-case time spent in the USB ISR, over and above
the time spent in its own USB drivers, and thus normally available for additional user service routines, is
as listed in
Table 23.
, and plotted in
Figure 7.
. Based on these results, the only possible values of oscillator
frequency are 24 and 36MHz.
Table 23. Oscillator Frequencies Suitable for Applications with USB
Figure 7. USB Demonstration Program USB Drivers Immunity versus Length of USB ISR (with
respect to Oscillator Frequency)
Note: USB 2.0, NEC720100A
Difference between Relative and Absolute Register Usage
It is strongly recommended to use relative registers in USB applications. It can save a lot of machine cy-
cles, which can be used for real USB tasks. But some steps must be followed.
The difference occurs at the beginning and end of the USB ISR. Using absolute registers (for example
using the
#pragma AREGS
directive) in the following code would be inserted:
Prescaler
F
OSC
(MHz)
Available Time (μs)
Number of 1T Instructions
0
12.0
Not reliable
Not reliable
1
24.0
140
280
2
36.0
264
792
AI09095
μPSD Oscillator Frequency (in MHz)
M
300
250
200
150
100
50
0
12.0
24.0
36.0
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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(shè)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(shè)備) |
| uPSD3253AV-24T1T | Flash Programmable System Devices with 8032 Microcontroller Core |
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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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