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Through the capacitor , a resistor or an amplifier circuit is supplied CPU, additional RF PLL circuit is also supplied as a basic clock signal.
( 3 ) with a normal reset signal. Just when the CPU for the power supply, the internal registers in a random state , the program is not running , so , CPU reset signal must be reset. Reset the phone is generally low end CPU reset , that is, after a certain internal CPU clock cycles to make various registers cleared , then here is high voltage up again , so that the CPU to run the program from scratch .
( 4 ) a logic circuit itself is normal. Logic circuit includes a CPU, font (FLASH), a chip (EEPROM), registers (SRAM), some models may be chips , font and registers synthetic one or two integrated circuits, this part of the line more, relatively speaking, maintenance , here is more difficult to deal with . When the CPU through with power, clock and reset three conditions, by the chip select signal CE and FLASH, SRAM, EEPROM contact , these chips will return output enable signal OE, SRAM will be used to write enable signal WE, and then through the data bus DATABUS ADDBUS address bus to transfer data to each other . CPU chip select signals are beginning work to determine the basic conditions .
3 software to run properly
Software is the CPU control various functions of the phone is switched on with the program . Set the boot process with the main store and the FLASH and EEPROM, some mobile phone software data can be backward compatible , so that these phones can be revised and upgraded ; Some phones due to software encryption , even if the phone is not compatible with the model ( such as Nokia ~ _5110 above ) . Therefore, if a software error or software may cause the phone does not boot the phone , of course , the software is not normal and may cause no network, no display, function disorder, many crashes and other failures .
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