READING AN SMS

ILLIAS28 · Joined: 11 Jan 2011 Posts: 42

Could you please help me,
i saw in a discussion an instruction for reading sms that is : fgets(GSM)
my question is: what is GSM? is that a library or what?
_________________
i am newbe

temtronic · Posted: Thu Jan 16, 2020 6:08 am

Quick comment...

GSM = Global System for Mobile...

The code says 'get a string of data from a serial device previously defined as GSM'.

Somewhere before that line a '#USE RS232(...stream=GSM...)' was coded to configure 2 I/O pins to connect to a GSM module.

Check the CCS manual for proper syntax and options !

Be aware that as it's code for 'string' operation , the GSM module MUST return a /0 in order for the PIC to proceed to the next line of code !

Ttelmah · Joined: 11 Mar 2010 Posts: 19520

No.
Gets, automatically appends a '\0', when a line feed is seen.

temtronic · Posted: Thu Jan 16, 2020 7:21 am

hmm, I always thought it looked for the 'end of string' delimiter not 'make a string' by adding the /0.
That gets me wondering what happens when there is no linefeed in the incoming data ?

Ttelmah · Joined: 11 Mar 2010 Posts: 19520

Gets, terminates when a line feed or null is seen.
It is really best thought of as a 'get line' function.
From K&R:

ILLIAS28 · Joined: 11 Jan 2011 Posts: 42

Thank you very much for your help guys;
but what is the difference between this command and the AT command for reading SMS: printf("AT+CMGR=%d\r",indx);
_________________
i am newbe

Ttelmah · Joined: 11 Mar 2010 Posts: 19520

Whoa.
Very different things completely.

Gets, is a C command to 'read' the reply from the modem.
The AT command is a string sent _to_ the modem, to get a reply.

You send an AT command (using printf), and then the reply from the
modem can be read with gets.