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4×4 matrix keyboard principle and program

  • 2013-09-22
  • 25.53KB
  • Points it Requires : 1

1. Read the state of the keyboard first to get the characteristic code of the key. First, output a low level from the upper four bits of the P1 port, and a high level from the lower four bits, and read the keyboard state from the lower four bits of the P1 port. Then output a low level from the lower four bits of the P1 port, and a high level from the upper four bits, and read the keyboard state from the upper four bits of the P1 port. Combining the results of the two reads can get the characteristic code of the current key. Using the above method, we get the characteristic codes of 16 keys.

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