Smart Machine Smart Decision
SIM800H _Hardware Design_V2.03
42
2016-10-10
Customer could cascade a less than 1K resistor to enhance the ESD performance, the connection diagram is as
following:
KBRx
KBCx
20K
<1K
Module
Figure 39: Keypad reference circuit
Whether using a 5*5 keys or 5*5*2 keys, the module can also detect the two buttons pressed. But when using a
5*5*2 button, the same row, column two buttons pressed at the same time can’t be detected, as shown below:
KBRx
KBCx
20K
Module
Figure 40: Keypad detected
Table 22: Pin definition of the keypad interface
Pin name
Pin number
Function
Default state
KBC0
20
Keypad matrix column
Pull up
KBC1
25
Pull up
KBC2
22
Pull up
KBC3
21
Pull up
KBC4
24
Pull up
KBR0
62
Keypad matrix row
Pull down
KBR1
60
Pull down
KBR2
61
Pull down
KBR3
23
Pull down
KBR4
63
Pull down
Note: Please be sure to increase the ESD protection devices in product design phase, and make sure have ESD protection devices
in the final product.
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