Smart Machine Smart Decision
4.9.2. PCM Interface
Refer to the following figure for PCM design:
Figure 37: PCM reference circuit
4.9.3. LCD Display/SPI Interface
SIM800H&SIM800L provides a serial interface. It could be used as SPI interface in the embedded AT
application.
SIM800H&SIM800L_Hardware Design_V2.02 43
2015-07-27
Module
LCD
GND
GND
SPI_DATA
DISP_CS
DISP_RST
DISP_D/C
DISP_CLK
DISP_DATA
SPI_CS
SPI_RST
SPI_D/C
SPI_CLK
Figure 38: LCD reference circuit
4.9.4. SD Card Interface
Figure 39: SD reference circuit
Smart Machine Smart Decision
If power supply is 2.8V for SD card, customer can use VDD_EXT; if power supply is 3.3V, please use external
design LDO.
4.10. Keypad Interface
The keypad interface consists of 5 keypad column outputs and 5 keypad row inputs, with total 5*5*2, which is 50
keys.
Module keys have two connections: connections 1, which can support 25 keys; connections 2, which can
support 50 keys.
Connections 1:
Figure 40: 25 keys reference circuit
Note
：
According to the traditional 5*5 to design buttons, when there is spare KBC or KBR, customer can execute AT command
to define as GPIO for details please see the relevant manuals.
Connections 2:
Module supports a new key connection, can support 50 keys, which meets full keyboard demand, the connection
diagram is as following:
