Attention Commands or, more commonly referred to as, AT commands are the method in which one communicates to modems. The following guide runs down some of the more common commands used when interfacing with a modem and establishing a connection to the cellular network.
AT commands are a necessary part of troubleshooting cellular hardware. Since our customers use a wide range of Hologram Compatible Hardware, it behooves us to discuss AT commands in the abstract, because there are so many out there.First things first: is there a library available for your board? If so, use thatWe have some libraries in our Hologram education github and are always looking for more
Using AT commands are required in two situations:
Variable size of messageMore diverse than a register set like in i2c or SPI commsThis also allows the SDK to communicate over the abstracted interfaceIf talking from a computer, will need something like a USB -> serial
Each manufacturer covers a subset of the entire amount of commands available. Each hare
There are 3 types of AT commands in our common set These characters are operators for AT commands.
To begin, use your favorite terminal program (Teraterm, Putty, GTKTerm, etc.), to establish a serial connection to your Modem. (Insert link to sending AT commands to a nova)CommandFunctionSample ResponseATAttention - This Command is used to check communications with the modemOKATIModule NumberSARA-U201-03B-00AT+CGMIManufacturer Specific Identityu-bloxAT+CGMMManufacturer Specific Model IndentitySARA-U201AT+GMMManufacturer Specific Model IndentitySARA-U201AT+CSQCheck Signal Strength+CSQ: 13,3AT+CCIDCheck the SIM ID+CCID: 1234567890123456789AT+CPIN?Check the SIM PIN+CPIN: READYAT+CFUN?Determine what functionality the Modem is on+CFUN: 1,0AT+CREG?Network Registration Status+CREG: 0,5AT+CGREG?GPRS Network Registration Status+CGREG: 0,5AT+CGDCONT?Read PDP context's parameters (APN)+CGDCONT: 1,"IP","hologram","0.0.0.0",0,0AT+CGDCONT=1,"IP","hologram"Set the APN to hologramOKAT+CGACT?PDP conext+CGACT: 1,0AT+COPS?Network Registration Status+COPS: 1,2,"310260",2AT+COPS=?Networks in reach+COPS: (1,"AT&T","AT&T","310410",2),(2,"T-Mobile","T-Mobile","310260",2),,(0-6),(0-2)