What is the at instruction set often used in the development of IOT devices?

What is? AT Instructions

AT namely Attention,AT Instructions are used to define Terminal equipment TE(TerminalEquipment) and Mobile MT(Mobile Terminal) The rules of interaction , When Terminal equipment Enter a AT After the instruction , Communicating with Mobile Will reply with a result , So one-on-one . As shown in the figure below .

Wide area communication GSM In the network , The user can go through AT Order to proceed call 、 SMS 、 telephone book 、 Data business 、 Fax And so on .

AT Command related nouns

AT Command format

AT The order is based on AT To begin with , The string at the end of the character ,AT The response packet of the instruction is in . Whether each instruction is executed successfully or not has a corresponding return . Other unexpected information modules will have corresponding information prompts , The receiving end can do corresponding processing .

Every AT Only one... Can be included in the instruction AT Instructions ; except AT Two characters apart , Up to 1056 The length of characters （ Including the last empty character ）.

AT The instruction set can be divided into three types ：

common AT Instructions

Query module serial number  AT+CGSN

AT+CGSN=<snt>, If no write <snt>, Only return to "OK”.

• <snt>=0, return <sn>.

• <snt>=1, return IMEI（ International mobile device identification number ）, Each module is unique .

• <snt>=2, return IMEISV（ International mobile radio device identity and software version ）.

• <snt>=3, Return the software version number SVN.

 dispatch orders ：AT+CGSN=1       Module return ：+CGSN:868744036640526      OK

Check firmware version  AT+CGMR

Execute this command to return the firmware version .

 dispatch orders ：AT+CGMM       Module return ：<Revision>       OK

Query terminal error  AT+CMEE

Used to set up terminal error reporting , When enabled send AT When an error is executed, the terminal will return the error code , This makes it easy to locate the problem .

 Turn on error code reporting  dispatch orders ：AT+CMEE=1 Module return ：OK

Restart the module  AT+NRB

For terminal device restart .

 dispatch orders AT+NRB Module return ：REBOOTING****Boot: UnsignedSecurity B.. VerifiedProtocol A.. VerifiedApps A...... VerifiedREBOOT_CAUSE_APPLICATION_ATNeulOK

Query signal strength  AT+CSQ

The return value is +CSQ：<rssi>,<ber>.rssi The bigger it is , The stronger the signal . Signal strength and rssi The conversion formula is ： Signal strength =113dBm+(rssi*2).ber Field not used , Equal to 99.

 dispatch orders ：AT+CSQ Module return +CSQ:31,99OK

Check if the network is active  AT+CGATT

return ：+CGATT:1, Indicates that the network is activated ; If returns ：+CGATT:0, It means the network is not activated , Please try to restart the module to activate the network .

 dispatch orders ：AT+CGATT? Module return ：+CGATT:1OK

Query network registration status  AT+CEREG

This command is used to query the terminal EPS Network registration status . When enabled to prompt , The network registration status information of the terminal has changed , Will actively report to the user terminal . Different settings allow you to report EPS Registration status 、 Location area code 、 community ID、 Access technology and other information of the service community , In general, it only needs to be set to auto report EPS Registration status .

 dispatch orders ：AT+CEREG=1 Module return ：OK After setting successfully , When the network registration status information changes , Will actively report to the user terminal , Such as ：+CEREG:1,1OK

Query the current connection status of the network  AT+CSCON

The return format is ：+CSCON:<n>,<mode>?

• <n> It's notification settings . Value and description ：0 To cancel asynchronous notification , When the network is connected , Serial port will not actively report +CSCON command ;1 To enable asynchronous notification , Serial port actively reports +CSCON.

• <mode> Is the current module connection status , Value and description ：0 be in IDLE state ,1 In connected state . When in IDLE In the state of , Just send the data or restart the device , It will become connected .

 dispatch orders ：AT+CSCON? Module return ：+CSCON:0,1OK

Set the RF function of the module  AT+CFUN

This command is used to set and query whether the RF function of the module is on .

AT+CFUN=0  // Turn off RF function OKAT+CFUN=1  // Turn on the RF function of the module OKAT+CFUN?   // Check the RF on status of the module +CFUN:1     // RF function has been turned on successfully , If reply 0 Usually because SIM The circuit of the card is not connected to the module successfully