Pic to GSM Phone connection (HSerin problems)

[NavMicroSystems]

... do I need an hex inverter? or a max232?

You will never get this to work if you don't take the time to read any datasheet.

[dimitrin]

don't quite understand your comment.

thanks for your input.

[NavMicroSystems]

don't quite understand your comment...

...nor RS232

[dimitrin]

because it does work with rs 232.

thanks again for you help

[aruran]

I got an Ericsson T18 phone, which works with the data cable for AT commands.. Going through the internet I found that it doesn't support Text mode, Only pdu mode available. So can I make it work by using bitmaniac's PDU decoder. And I am going to use PIC16F877A. If I do the necessary changes it should work right......

thanks in advance
aruran

[PIC Coder]

Hello,
I am look out for technical details of Samsung SCH-N356. I also want to make SMS controled relay. Please suggest.
Bye

[aruran]

Hai all,

First of all thank you all for the help rendered. I have successfully made a Ericsson T18 to send SMS using PIC16F877A. I give the PIC using I2C bus some data from a main PIC for my microcontroller project. I have written a dynamic PDU encode routing to handle the dynamic texts sent by the main pic. This was achieved mainly from the help of bitmaniac's PDU encode...

Thank you all
aruran

[Royce]

Hi

I am very new to PIC's so please excuse some of the comments that I have added to the following code.

I have put this together using data that was available earlier in this post. I have got the SMS sending working great whenever I push a button but I am also wanting an LED to be switched on when the GSM modem receives and SMS containing "SWITCH"

I think I have got everything that I require within the program but I am wondering what commands I should use in order to read the GSMBuffer then if it is true then switch on the LED.

I have added the line just to give an idea of what I'm trying to do:

IF GSMBUFFER = "SWITCH" THEN LED = 1

Here is the code:

' Setup PIC tx and rx serial port
DEFINE OSC 8
DEFINE HSER_TXSTA 20h
DEFINE HSER_RCSTA 90h
DEFINE HSER_BAUD 9600
DEFINE HSER_CLROERR 1

'Setup the names that will be used throughout the program for the led and switch
PushButton var PORTB.0 ' Setup the name PushButton to mean PortB input 0
LED VAR PORTB.1 ' Setup the name LED to mean PortB output 1

' SMS receive buffer setup:
GSMBUFFER VAR BYTE[16] '16 is used to tell buffer to store max of 16 characters
Caller VAR BYTE[13] '13 is used to tell buffer to store max of 16 characters
GSMTime VAR BYTE[17] '17 is used to tell buffer to store max of 16 characters

' Set all PortB i/o 1 to be an output and all other i/o as inputs
TRISB = %11111101

Main:

IF PushButton = 0 THEN SMS 'If button is pressed then run the SMS routine below

goto main ' however if the button is not pushed then just go back to the Main
' routine to wait for the button to be pressed

SMS: ' this is the SMS commands routine in order to send an SMS

HSEROUT ["AT" ,13,10] ' send AT to modem followed by a CR and line feed

HSERIN 5000, SMS, [WAIT("OK")] ' now wait for 5secs until OK is received however
' if it is not then goto the SMS routine again

HSEROUT ["AT+CMGF=1" ,13,10]

HSERIN 5000, SMS, [WAIT("OK")]

HSEROUT ["AT+CMGS=+447977578999"]

HSEROUT [13,10]

HSERIN 5000, SMS, [WAIT(">")]

HSEROUT ["BUTTON HAS BEEN PRESSED!"]

HSEROUT [26] ' this is ASCII for Ctrl+Z of which completes SMS sending

HSERIN 15000, SMS, [WAIT("+CMG")] ' then PIC should receive +CMG from modem

HSEROUT [10] 'ascii code for a line feed

goto main

READSMS: 'Use this routine to read first 16 characters of new messages and then
' store them in the GSMBUFFER variable above then you are able to add a line at
' the end in order for an led to be switched on whenever the modem receives the
' correct SMS command such as LED ON or SWITCH etc

HSEROUT ["AT+CMGF=1",13,10] 'Instruct modem to use text mode

HSerout ["AT+CMGL",13,10] 'List new Messages

' Below I Read Caller ID, time and 16 CHARs of Message
' The timeout value in the HSERIN statement is important, it takes some time
' before the phone replies to the AT+CMGL command
' skip works like this: skip 4 (skips 4 characters) - this is a sample of the
' message that would be received after the AT+CMGL command is sent:
' +CMGL: 2,"REC UNREAD","+447977578999" Test
' Please note that I can't seem to receive the time in the reply as in this
' example: (of which the line of code is written for below - so maybe I should
' edit the line of code below in order to miss it - also remember to update
' GSMTime variable above i.e. remove it if your going to adit the line below)
' +CMGR: "REC READ","+xx1234567890",,"05/05/26,17:19:23+00" GOOD
' Loop could be setup as a routine such as:
' Loop:
' List new Messages again - as above (think about it)
' HSerout ["AT+CMGL",13,10]

HSerin 5000,loop,[wait("UNREAD"),skip 3,STR Caller\13,skip 4,STR GSMTime\17,skip 6, STR GSMBUFFER\16\13]

' Basically in the above line, \13 - stores 13 characters and \17 - stores 17 characters etc into
' each of the buffers i.e. Caller & GSMTime etc etc

HSerout ["AT+CMGD=1;+CMGD=2",13,10] 'Intruct modem to delete SMS's from location
' 1 & 2 as this is where any new messages will be stored, so its a good idea to
' delete them after we have processed the SMS command above - please note that
' it would be a good idea to wait for an OK after this command but we can add
' this at a later time

' --- Put your code to output the result here i.e. IF gsmbuffer = (your sms command) then goto
' subroutine etc

IF GSMBUFFER = "SWITCH" THEN LED = 1

Thank you for your time.

Kind Regards,
Royce

[Ioannis]

On the following code the phone responds ..."REC READ",... if the message was read sometime before. If you have a fresh new message then this becomes UNREAD as you state on your code.

So, why don't you change your code to:

HSerin 5000,loop,[wait("READ"),... since the word READ is present all the time?

Ioannis

' +CMGR: "REC READ","+xx1234567890",,"05/05/26,17:19:23+00" GOOD
' Loop could be setup as a routine such as:
' Loop:
' List new Messages again - as above (think about it)
' HSerout ["AT+CMGL",13,10]

HSerin 5000,loop,[wait("UNREAD"),skip 3,STR Caller\13,skip 4,STR GSMTime\17,skip 6, STR GSMBUFFER\16\13]

[Royce]

Thank you for the info.

I was wondering if you could tell me how I should use the data that is captured within the GSMBuffer i.e. the SMS text as I would like use this to switch on an LED. Should it be something like this:

IF GSMBuffer = Switch on then LED = 1

Thanks in advance.

Kind Regards,
Royce

[Ioannis]

PBP does not have such string compring capabilities.

You have to make your own subroutine to compare byte to byte the two string array. Like that:

i=0
while i less_than gsmbuffer_length (I cant sen the less character! Why?)

if gsmbuffer[i]=compare_array[i] then
'gsmbuffer[i]=0
i=i+1
else
goto wrong_sms
endif
wend
correct_sms:
'your code here

wrong_sms:
'your code here

You understand that in compare_array you have to put your characters in some other place of the program prior to the above subroutine.

[Royce]

Thanks again but I'm afraid I dont quite understand. Really sorry but would it be possible to be little clearer.

Thanks again.

Kind Regards,
Royce

[Ioannis]

Hmm, what part you are not understanding?

Ioannis