My quick notes regarding a SIM800L module on an inexpensive SIM800L EVB “SIM800LV2.2” carrier board from eBay. Communicates happily with a computer through a generic USB<>TTL converter, 5V logic levels and 5V power at 9600 baud. Carrier board includes a TTL level shifter and 2 diodes in series to drop the voltage from 5V to ~3.6V.
AT+CMGF=1 # Set modem to text mode AT+CMGS="phone_number" # Start composing a message to phone_number
The second command will open a message composing mode, CTRL+Z to send.
AT+CMGF=1 # Set modem to text mode AT+CMGL # List unread received texts AT+CMGL="ALL" # List all received texts, read or not AT+CMGR=<id> # Get a message with id
ATD+ phone_number; # Dial phone_number ATH # Hang up ATA # Accept incoming call
AT+CNETSCAN # Scanning for neighbouring cells AT+GSV # Show module information AT+CNUM # Show SIM phone number AT+CSQ # Show signal levels AT+CCLK # Show current date/time AT+COPS? # Show which operator the module is connected to
Full AT commands documentation for this chipset: SIM800_Series_AT_Command_Manual_V1.09