With 51 single-chip microcomputer, the fingerprint module, 12864, and other components of the matrix keyboard,
Set the "D" key to class mode button, once again, press the "D" for the course, to sign in during this period, and in order to statistics the number of absence and late, but! D key press occasionally to work is how to return a responsibility? Because can't set class model, so can statistical number, use multimeter measurement, that is no problem! How to do? !!!!!!!!!

CodePudding user response:

There is something wrong with the key program?

CodePudding user response:

If you can't online debugging, then fix a serial port first, and then the printf observe process state and output from the program, so that we can get twice the result with half the effort

CodePudding user response:

Physical key needs to be done away, hardware, software way, and must be reliable,

CodePudding user response:

Should be the keys no shake, or shaking time too short, causes the program processing key time is too short, and had better have a button press and release the judgment, if only to press the judgment, not loosen, easily lead to a key as secondary or N times,