可冰

系统手册[2-15]
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RESET
When the nRESET signal goes LOW, ARM920T abandons the executing instruction and then continues to fetch
instructions from incrementing word addresses.
When nRESET goes HIGH again, ARM920T:
1. Overwrites R14_svc and SPSR_svc by copying the current values of the PC and CPSR into them. The value of
the saved PC and SPSR is not defined.
2. Forces M[4:0] to 10011 (Supervisor mode), sets the I and F bits in the CPSR, and clears the CPSR's T bit.
3. Forces the PC to fetch the next instruction from address 0x00.
4. Execution resumes in ARM state.
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当~nRESET信号(低电平有效)有效时,ARM920T终止当前指令的执行,而连续不断地获取下一字地址处的指令;当~nRESET恢复为高电平时,ARM920T执行下面的操作:
1. 拷贝当前PC和CPSR的值到R14_svc和SPSR_svc中.而保存过的PC和SPSR的值未定义(不确定).
2. M[4:0] <-- 10011,转到Supervisor模式,设置CPSR中的I、F位为1(禁止中断),并对T位清零(进入ARM状态).
3. 设置PC从0x00处获取下一条指令.
4. 在ARM状态下执行指令.
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