SimCom SIM800 Series, Hardware Design

Page: 43 / 67

Smart Machine Smart Decision
SIM800_Hardware Design_V1.10 43 2018-08-13
KBRx
KBCx
20K
<1K
Module
Figure 39: Enhance the ESD performance of keypad circuit
Module can detect two buttons pressed synchronously at both the traditional and extended keypad connection,
but customer should notice that, do not assign keys which will be pressed at the same time on same KBC and
KBR when implement the extended keypad design. The following figure is an example to explain this situation,
“CTRL” and “A” can not be recognized if the two buttons were pressed at the same time.
KBRx
KBCx
20K
Module
Figure 40: Keypad detected
Table 20: Pin definition of the keypad interface
Name Pin Function Default state
KBC0 51
Keypad matrix column
Pull up
KBC1 50 Pull down
KBC2 49 Pull down
KBC3 48 Pull down
KBC4 47 Pull down
KBR0 44
Keypad matrix row
Pull down
KBR1 43 Pull down
KBR2 42 Pull down
KBR3 41 Pull down
KBR4 40 Pull down