Matrix keyboard, 3×3 matrix keyboard, digital tube display corresponding button, dynamic scanning, interrupt implementation.
The pull-up resistor attribute should be set to “digitalâ€.
3x3 matrix keyboard scanning principle and scanning programThe 9 buttons are arranged in 3 rows and 3 columns. The first row connects one end of each button to form a row line, and the first column connects the other ends of each button to form a column line, so that there are 3 rows and 3 There are a total of 6 lines. We connect these six lines to the 6 IO ports of the STM32. The program scans the keyboard to detect 9 keys.
Regardless of the stand-alone keyboard or the matrix keyboard, the principle that the MCU detects whether it is pressed is the same, that is, whether the I/O port corresponding to the key is low. The independent button has one end fixed to a low level, and the MCU write program is more convenient to detect. Both ends of the matrix keyboard are connected to the I/O port of the MCU. Therefore, it is necessary to manually send a low level through the I/O port of the MCU during the detection. When detecting, first send a column low, the other columns are high (we determine the number of columns at this time), and then immediately detect whether each row has a low level, if a certain behavior is detected low ( At this point we have determined the number of rows), then we can confirm which row of the row is currently pressed, use the same method to send each column a low level, and then poll once to see if each row becomes low. Flat, so that all the buttons can be detected. Of course, we can also set the row line low and scan the column for low level. This is the detection principle and method of the matrix keyboard.
SETB P1.0; first of all, set one first
SETB P1.1
SETB P1.2
SETB P1.3
SETB P1.4
SETB P1.5
KEY: CLR P1.0; the line is cleared
CLR P1.1 CLR P1.2
JNB P1.3, KEY0; determine if there is a button press
JNB P1.4, KEY0
JNB P1.5, KEY0
SJMP KEY; no button presses back to KEY to continue to check if there is a button press
KEY0: LCALL DELAY ; call delay function
CLR P1.0; P1.0 is cleared, P1.1, P1.2 are set to one
SETB P1.1
SETB P1.2
JNB P1.3, KEY1; P1.3 is zero, then the button is pressed, jump to the button KEY1
JNB P1.4, KEY2
JNB P1.5, KEY3
SETB P1.0; P1.1 is cleared, P1.0, P1.2 is set to CLR P1.1
SETB P1.2
JNB P1.3, KEY4
JNB P1.4, KEY5
JNB P1.5, KEY6
SETB P1.0; P1.2 is cleared, P1.0, P1.1 are set to one
SETB P1.1
CLR P1.2
JNB P1.3, KEY7
JNB P1.4, KEY8
JNB P1.5, KEY9
SJMP KEY; if there is no button press, jump back to the button query program
KEY1: LCALL PRO1; call subroutine of button one
LJMP KEY; return to continue to query whether the button is pressed
KEY2: LCALL PRO2
LJMP KEY
KEY3: LCALL PRO3
LJMP KEY
KEY4: LCALL PRO4
LJMP KEY
KEY5: LCALL PRO5
LJMP KEY
KEY6: LCALL PRO6
LJMP KEY
KEY7: LCALL PRO7
LJMP KEY
KEY8: LCALL PRO8
LJMP KEY
KEY9: LCALL PRO9
LJMP KEY
PRO1: . ; button one processing subroutine
RET ; subroutine return
PRO2:
. RET
PRO3:
RET
PRO4:
RET
PRO5:
RET
PRO6:
RET
PRO7:
RET
PRO8:
RET
PRO9:
RET
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