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SIM900 GSM/GPRS TTL UART Modem - User Manual
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Example: With Local Echo enabled:
Transmit: AT\r
Receive: AT\r\r\nOK\r\n
SETTINGS FOR EASY MICROCONTROLLER COMMUNICATION
When communicating with the GSM Modem using a microcontroller, you usually want very short responses, no
local echo, and no startup messages.
Sticking on the &W to the end of the command saves the setting into memory.
ATV0&W\r Enable short response
ATE0&W\r Disable Local Echo
AT+CIURC=0;&W\r Disable “CALL READY” Startup Message
Now instead of commands returning OK or ERROR in plain text, as well as repeating all written commands, the
GSM Modem will not echo what you transmit and the GSM Modem will return error codes in single bytes. For
example, instead of:
Transmit: AT\r
Receive: \r\nOK\r\n
You’ll have:
Transmit: AT\r
Receive: \r\n0\r\n
SAMPLE AT COMMANDS CODE
1. PHONE COMMUNICATION
Goal: Call a phone
Dial 123-456-7890 = ATD1234567890;\r
This command returns OK or ERROR. Returns NO CARRIER when phone hangs up
2. SEND A TEXT MESSAGE
Goal: Send a text
AT+CMGF=1\r
Returns OK or ERROR
