参数资料
型号: AT90USB1287-MUR
厂商: Atmel
文件页数: 50/106页
文件大小: 0K
描述: MCU AVR 128K FLASH 16MHZ 64QFN
产品培训模块: MCU Product Line Introduction
megaAVR Introduction
标准包装: 1,000
系列: AVR® 90USB
核心处理器: AVR
芯体尺寸: 8-位
速度: 16MHz
连通性: EBI/EMI,I²C,SPI,UART/USART,USB,USB OTG
外围设备: 欠压检测/复位,POR,PWM,WDT
输入/输出数: 48
程序存储器容量: 128KB(128K x 8)
程序存储器类型: 闪存
EEPROM 大小: 4K x 8
RAM 容量: 8K x 8
电压 - 电源 (Vcc/Vdd): 2.7 V ~ 5.5 V
数据转换器: A/D 8x10b
振荡器型: 内部
工作温度: -40°C ~ 85°C
封装/外壳: 64-VFQFN 裸露焊盘
包装: 带卷 (TR)
48
7593L–AVR–09/12
AT90USB64/128
7.9.1
CLKPR – Clock Prescale Register
Bit 7 – CLKPCE: Clock Prescaler Change Enable
The CLKPCE bit must be written to logic one to enable change of the CLKPS bits. The CLKPCE
bit is only updated when the other bits in CLKPR are simultaneously written to zero. CLKPCE is
cleared by hardware four cycles after it is written or when CLKPS bits are written. Rewriting the
CLKPCE bit within this timeout period does neither extend the timeout period, nor clear the CLK-
PCE bit.
Bits 3..0 – CLKPS3..0: Clock Prescaler Select Bits 3 - 0
These bits define the division factor between the selected clock source and the internal system
clock. These bits can be written run-time to vary the clock frequency to suit the application
requirements. As the divider divides the master clock input to the MCU, the speed of all synchro-
nous peripherals is reduced when a division factor is used. The division factors are given in
The CKDIV8 Fuse determines the initial value of the CLKPS bits. If CKDIV8 is unprogrammed,
the CLKPS bits will be reset to “0000”. If CKDIV8 is programmed, CLKPS bits are reset to
“0011”, giving a division factor of 8 at start up. This feature should be used if the selected clock
source has a higher frequency than the maximum frequency of the device at the present operat-
ing conditions. Note that any value can be written to the CLKPS bits regardless of the CKDIV8
Fuse setting. The Application software must ensure that a sufficient division factor is chosen if
the selected clock source has a higher frequency than the maximum frequency of the device at
the present operating conditions. The device is shipped with the CKDIV8 fuse programmed.
Table 7-10.
Clock prescaler select.
Bit
7
6
543
2
1
0
CLKPCE
CLKPS3
CLKPS2
CLKPS1
CLKPS0
CLKPR
Read/write
R/W
R
R/W
Initial value
0
See bit description
CLKPS3
CLKPS2
CLKPS1
CLKPS0
Clock division factor
00
1
00
01
2
00
10
4
00
11
8
01
00
16
01
32
01
10
64
01
11
128
10
00
256
10
01
Reserved
10
Reserved
10
11
Reserved
11
00
Reserved
相关PDF资料
PDF描述
AT90USB1287-AUR MCU AVR 128K FLASH 16MHZ 64TQFP
VE-BTF-IX CONVERTER MOD DC/DC 72V 75W
VI-B3X-IX-F2 CONVERTER MOD DC/DC 5.2V 75W
VE-BTF-IW CONVERTER MOD DC/DC 72V 100W
VI-B3X-IW-F4 CONVERTER MOD DC/DC 5.2V 100W
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