[proteus simulation] Arduino uno uses 74ls148 to extend interrupt

【Proteus Simulation 】Arduino UNO utilize 74LS148 Extended interrupt

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• Proteus Simulation demonstration
  

Arduino UNO Hardware only 2 External interrupt pins 1 and 2, utilize 74LS148 You can extend the 8 External interrupts , But it will cost extra 3 Data pins , The function realized by interrupt is much less than that of traditional port scanning CPU spending . If you will 2 All external interrupts are extended , It can be extended to 16 External middle fracture , And there is no need to rely on other third-party library functions to implement .

AVR Knowledge of operating instructions

• AVR Single chip microcomputer IO Port is a standard two-way port , First, set IO The state of the mouth , namely ： Input or output .

DDRx Register is AVR MCU port direction register , By setting DDRx You can set x The state of the port .
DDRx The corresponding bit of the port direction register is set to 1 Corresponding x The corresponding bit of the port is the output state ,DDRx The corresponding bit of the port direction register is set to 0 Corresponding x The corresponding bit of the port is the input state .

• for example ：

DDRA = 0xFF; // Set port A All ports are in output state , because 0xFF The corresponding binary is 11111111b
DDRA = 0x0F // Set port A high 4 Bit is input status ࿰