參數(shù)資料
型號: HCD404084
廠商: Hitachi,Ltd.
英文描述: Low-Voltage AS Microcomputers with On-Chip A/D Converter(帶片上A/D轉(zhuǎn)換器的低壓微計算機)
中文描述: 低電壓如同在微機芯片的A / D轉(zhuǎn)換器(帶片上的A / D轉(zhuǎn)換器的低壓微計算機)
文件頁數(shù): 56/162頁
文件大?。?/td> 482K
代理商: HCD404084
HD404374/HD404384/HD404389/HD404082/HD404084 Series
56
System Clock Gear Function
The MCU has a built-in system clock gear function that allows the system clock divided by 4 or by 32 to be
selected by software for the instruction execution time. Efficient power consumption can be achieved by
operating at the divided-by-4 rate when high-speed processing is needed, and at the divided-by-32 rate at
the other times. Figure 21 shows the system clock conversion method.
System clock conversion from division-by-4 to division-by-32 is performed as follows. First, make the
division-by-32 setting (SSR0 write), then set the gear enable flag (GEF: $021,3). This flag is used to
distinguish between gear conversion and a transition to standby mode. Next, execute an SBY instruction.
When the gear enable flag is not set, standby mode is entered; when this flag is set, gear conversion mode
is entered. In this case a transition is made to standby mode for the duration of the gear conversion, but
after the synchronization time has elapsed, a transition is made automatically to active mode. As soon as
the transition is made to active mode, the gear enable flag is reset.
The same procedure is used for conversion from division-by-32 to division-by-4.
Clear all interrupts, then disable interrupts, before carrying out gear conversion. Incorrect operation may
result if an interrupt is generated during gear conversion.
Division-by-32 setting (SSR0 = 1)
Set gear enable flag
Execute SBY instruction
Execute next instruction
Synchronization time
Division-by-4 setting (SSR0 = 0)
Set gear enable flag
Execute SBY instruction
Execute next instruction
Synchronization time
Figure 21 System Clock Division Ratio Conversion Flowchart
相關PDF資料
PDF描述
HCD40C4084 Low-Voltage AS Microcomputers with On-Chip A/D Converter(帶片上A/D轉(zhuǎn)換器的低壓微計算機)
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HCD44780UA00 320 x 240 pixel format, CFL backlight available with power harness
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