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參數(shù)資料
| 型號： | AT43USB325E-AC |
| 廠商： | ATMEL CORP |
| 元件分類： | 微控制器/微處理器 |
| 英文描述： | Multimedia USB Keyboard Controller with Embedded Hub |
| 中文描述： | 8-BIT, 12 MHz, RISC MICROCONTROLLER, PQFP64 |
| 封裝： | 1.40 MM HEIGHT, PLASTIC, MS-026-ACB, LQFP-64 |
| 文件頁數(shù)： | 105/109頁 |
| 文件大?。?/td> | 643K |
| 代理商： | AT43USB325E-AC |
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105
3355C–USB–4/05
AT43USB325
12. Errata Sheet
Errata (All Date Codes): Missed Watchdog Timer Reset
12.1
Problem
There is a synchronization problem between the watchdog clock and the AVR clock. Even
though the clock inputs to both the watchdog timer and the AVR core are generated through the
same crystal, the two clock sources are not going through the same PLL. The AVR is clocked at
12 MHz and the watchdog timer is clocked at 1MHz. The WDR (Watchdog Reset) instruction is a
one-clock-cycle instruction. As such, when a watchdog timer reset occurs due to a WDR, the
watchdog timer may miss the reset. This happens frequently if the AVR is clocked much faster
than the watchdog timer.
12.2
Fix/Workaround
A workaround is to invoke the WDR repetitively to ensure that the watchdog timer will be able to
receive the reset signal. If the AVR runs at 12 MHz, the WDR command must be invoked four-
teen times back to back.
The following is the sample code for resetting and arming the watchdog timer, assuming the
AVR is running at 12 MHz:
asm ( "ldi r16,15\n WDR\n WDR\n WDR\n WDR\n WDR\n WDR\n WDR\n WDR\n WDR\n
WDR\n WDR\n WDR\n WDR\n out 0x21,r16 " );
To disarm and disable the watchdog, do the following:
asm ( "ldi r16,0x18\nldi r17,0x10\n\n out 0x21,r16\n out 0x21,r17 " );
Please note that if the AVR runs at 24 MHz, the WDR should be invoked twenty-six times.
相關(guān)PDF資料 |
PDF描述 |
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| AT43USB325E-AU | Multimedia USB Keyboard Controller with Embedded Hub |
| AT43USB326-AC | Multimedia USB Keyboard Controller with Embedded Hub |
| AT43USB326-AU | Multimedia USB Keyboard Controller with Embedded Hub |
| AT43USB351M-AC | Full-speed/Low-speed USB Microcontroller with ADC and PWM |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AT43USB325E-AU | 功能描述:USB 接口集成電路 USB KEYBOARD CONTROL w/HUB - IND TEMP RoHS:否 制造商:Cypress Semiconductor 產(chǎn)品:USB 2.0 數(shù)據(jù)速率: 接口類型:SPI 工作電源電壓:3.15 V to 3.45 V 工作電源電流: 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WLCSP-20 |
| AT43USB326 | 制造商:ATMEL 制造商全稱:ATMEL Corporation 功能描述:Missed Watchdog Timer Reset |
| AT43USB326_06 | 制造商:ATMEL 制造商全稱:ATMEL Corporation 功能描述:Multimedia USB Keyboard Controller with Embedded Hub |
| AT43USB326-AC | 功能描述:USB 接口集成電路 USB KEYBOARD F/LOGI- TECH - COM TEMP RoHS:否 制造商:Cypress Semiconductor 產(chǎn)品:USB 2.0 數(shù)據(jù)速率: 接口類型:SPI 工作電源電壓:3.15 V to 3.45 V 工作電源電流: 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WLCSP-20 |
| AT43USB326-AU | 功能描述:USB 接口集成電路 USB KEYBOARD FOR LOGITECH - IND TEMP RoHS:否 制造商:Cypress Semiconductor 產(chǎn)品:USB 2.0 數(shù)據(jù)速率: 接口類型:SPI 工作電源電壓:3.15 V to 3.45 V 工作電源電流: 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WLCSP-20 |
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