General Purpose Input/Output (Gpio); Keypad Interface - SimCom SIM900B Hardware Design

3.13 General Purpose Input/Output (GPIO)

3.14 Keypad Interface

The keypad interface consists of 5 keypad column outputs and 4 keypad row inputs. The basic configuration is 5
keypad columns and 4 keypad rows, giving 20 keys.
Table 13 : Pin definition of the keypad interface
Name
GPIO5/KBC0
GPIO4/KBC1
GPIO3/KBC2
GPIO2/KBC3
GPIO1/KBC4
GPIO9/KBR1
GPIO8/KBR2
GPIO7/KBR3
GPIO6/KBR4
The keypad interface allows a direct external matrix connection. A typical recommended circuit of the keypad is
as shown in the following figure.
SIM900B_Hardware Design_V2.01
Figure 30: Reference circuit of NETLIGHT
Pin Function
27
29
Keypad matrix column
31
33
35
39
41
Keypad matrix row
43
45
32
Smart Machine Smart Decision
2012-05-07