Pic to GSM Phone connection (HSerin problems)

[Rufinus]

Discovered strange thing. Works with S55. If i connect Tx line from the phone trough 1k resistor to one of the ports, serin2 will hang, waiting for an answer on that port. But when i quickly shorten this serin2 port to the ground, it starts working! And then hangs until the next command, then i short it and after it goes without problem to the end of the program. This trick does not work with HSERIN or SERIN. And only sometimes works with S65 phone.
With max232 doesnt work anyways.

Any ideas??



Here is my code:


DEFINE LOADER_USED 1

'UART hardware defines
DEFINE HSER_RCSTA 90h
DEFINE HSER_TXSTA 20h
DEFINE HSER_BAUD 9600
DEFINE HSER_CLROERR 1


'LCD defines
DEFINE LCD_DREG PORTA 'set LCD data port
DEFINE LCD_DBIT 0 'set starting data bit (0 or 4) if 4 bit bus
DEFINE LCD_RSREG PORTA 'set LCD register select port
DEFINE LCD_RSBIT 4 'set LCD register select bit
DEFINE LCD_EREG PORTB 'set LCD enable port
DEFINE LCD_EBIT 3 'set LCD enable bit
DEFINE LCD_BITS 4 'set LCD bus size (4 or 8 bits)
DEFINE LCD_LINES 2 'set number of LCD lines
DEFINE LCD_COMMANDUS 2000 'set command delay time in us
DEFINE LCD_DATAUS 50 'set data delay time in us
DEFINE OSC 20 'set crystal speed



b0 var byte
include "modedefs.bas"



'Main program


pause 1000 'wait for screen to sort get started

lcdout $FE,1, "Sending AT.."
pause 2000
HSEROUT ["AT", 13]
pause 500
HSEROUT ["ATE0", 13]
serin2 portc.4, 84, [str b0\10]
lcdout $FE, $C0, str b0\10
pause 3000

b0=0
lcdout $FE,1, "Asking model.."
pause 2000
HSEROUT ["at+cgmm", 13]
serin2 portc.4, 84, [SKIP 2, str b0\20]
lcdout $FE, $C0, str b0\20
pause 5000

b0=0
lcdout $FE,1,"Asking IMEI.."
pause 2000
Hserout ["at+cgsn", 13]
serin2 portc.4, 84, [SKIP 2, str b0\20]
lcdout $FE, $C0, str b0\20
pause 5000

b0=0
lcdout $FE,1,"Asking capabilities:"
pause 2000
Hserout ["at+gcap", 13]
serin2 portc.4, 84, [SKIP 2, str b0\20]
lcdout $FE, $C0, str b0\20
pause 5000


b0=0
lcdout $FE,1,"Asking time.."
pause 2000
Hserout ["at+cclk?", 13]
serin2 portc.4, 84, [SKIP 2, str b0\20]
lcdout $FE, $C0, str b0\20
end

[NavMicroSystems]

Rufinus,
I hate to say that, but you have got to do some homework.

Make yourself familiar with the principles of serial communitation and the datasheet of a MAX232.

Pay special attention on the MODES, (TRUE/INVERTED)

If you receiver is expecting the data line to be ILDE HIGH and your transmitter IDLES LOW, (and vice versa) you will see all kinds of strange phenomenon.

You are not really connecting one of the RS232 Outputs of the MAX to the phone or PIC, are you?
(you are about to kill the PIC and/or the Mobile)

[Rufinus]

RS232 output of max i do connect to the pic, but through 22k resistor.
Pic to phone both ways goes through 1k resistor.
There is no reason to connect rs232 straight to phone anyways, so i dont and would not. There is no problem now with the phone receiving commands. The problem is to receive answers on pic.

Regarding modes - tried both true and inverted, tried different baud rates.

Now it is connected to the pic without MAX. I still think it is the problem of levels.

If you have a good link in mind about serial communication, i would appreciate. Otherwise, gonna google.

Thanks for adwise anyways.

[NavMicroSystems]

RS232 output of max i do connect to the pic, but through 22k resistor.

A simple NPN Transistor and two resistors would do here.
(Invert the logic and shift the level to 5V)

Regarding modes - tried both true and inverted, tried different baud rates.
I still think it is the problem of levels.

Find out what level the Phones TX Pin has in Idle state, and what it is in active state.

If you have a good link in mind about serial communication, i would appreciate. Otherwise, gonna google.

Sorry, I don't have any link, but there are some good books, i.e.
"Serial Port Complete" by: Jan Axelson

[Rufinus]

I should report now, that the problem is solved!!
My thanks and respect goes to NavMicroSystems and Ioannis for helping me out.
Problem was solved by making a simple level shifter (so i can use phone with USART), using two BC 547 transistors.

Perhaps should make a simple conclusion, for those, who will work with Siemens S55/S65 phones.
There is no need in MAX232. Rx line of the phone can be connected to the PIC through 1k resistor. Tx line of the phone must be connected through simple level shifter. Written above is valid for PICs with USART onboard.
Pins 5 and 7 of the phone should be connected trough 10k resistors to pin 2.
Otherwise the phone will not detect the cable and will not accept commands from the PIC.

As a hint: if you dont have a spare connector for the phone, you can make one from AGP slot of the old PC motherboard, pin spacing is the same

-----------------------------------------------------------------------
And, of course, if you are not sure what are you doing, better dont do it!You can damage a lot of expensive things!
-----------------------------------------------------------------------

So now i will move on to next step - sending messages in PDU format.

[NavMicroSystems]

Rufinus,

I'm glad to hear you have got it to work!

Why do you want to use PDU format, doesn't the S55 support TEXT?

[Ioannis]

Ralph is right about the serial kwnoledge Rufinus. I was about to say almost the same things. If you don't own the Serial Complete, do so as soon as possible. It will help you the most.

Now, about your phone, it is sure a problem of levels, no question about it. It is just that we cannot guess anything. You have to find data sheets and read them from A to Z. Then you sure find why it behaves like the way you describe.

Regards,
Ioannis

[Rufinus]

Well, S55/S65 suports only PDU, unfortunately


I will get the book, because this is not my last project related to this matter.

Regarding datasheets. It is quite a tricky one, to find a complete datasheet for the phone. Even service manual i managed to find in internet, has the stamp on it: "For internal use only". So it is pretty much of poking and trying here and there, or call it guessing, if you will. And if the models of the phone are relatively new..

[Ioannis]

OK. PDU is one thing. Some phone do support ASCII some do not.
That's why I choose modules like Telit or Wavecom for serious projects or Nokia for experimenting.

But EVERY phone should answer 'OK' if addressed by 'AT'.

Ioannis

[NavMicroSystems]

Ioannis is right.

There are two GSM-Terminals I can recommend:

SIEMENS TC35i Terminal

and the Telit Terminal Ioannis has already mentioned.

[Russell]

i need a circuit diagram showing the connection between rs232 and pic16f84 for sending and receiving sms. ofcourse the phone is nokia.(AT supported). i am in desperate need of it.
thanks.

[Ioannis]

Have you ever used MAX232? (do a search on the forum and you will find a lot)

Have you an RS-232 cable for your Nokia Model?

Have you read the relevant AT commands for controlling you phone first through Windows terminal so to get familiar with the commands?

All these are necessary...

Ioannis

[rexilen]

i used pic16f873..nokia modem n30..lcd 2x16..3 sensors which give an input to pic +5V. this 3 sensor connected to portA from portA 0-2.rx and tx connected to max232 and used 4.5Mhz Crystal with 33pF capacitor. the LCD pins which are E connected to RB0, RS to RB3, DB4 to RB4, DB5 to RB5, DB6 to RB6, and DB7 to RB7.
well..my project do like this..if sensor 1,2,and 3 detect it will give an input to pic and LCD will diplay a message and nokia modem will send sms text message to specific phone number. well below is my program and it didnt work..the LCD didnt display anything and the modem didnt send any message.someone please help which part is wrong..

Pause 1000
DEFINE LCD_DREG PORTB 'Define PIC port used for LCD data line
DEFINE LCD_DBIT 4 'Define first pin of portC connected to LCD DB4
DEFINE LCD_RESREG PORTB 'Define PIC port used for RS line of LCD
DEFINE LCD_RSBIT 3 'Define PortC pin used for RS connection
DEFINE LCD_EREG PORTB 'Define PIC prot used for E line of LCD
DEFINE LCD_EBIT 0 'define the 3 bit communication
DEFINE LCD_LINES 2 'Define using a 2 line LCD
DEFINE LCD_COMMANDUS 2000 'define delay between sending LCD commands
DEFINE LCD_DATAUS 50 'Define delay time between data sent

DEFINE OSC 4

DEFINE HSER_TXSTA 20h
DEFINE HSER_RCSTA 90h
DEFINE HSER_BAUD 9600
DEFINE HSER_CLROERR 1

GSMBUFFER VAR BYTE[16]
Caller VAR BYTE[13]
GSMTime VAR BYTE[17]

Init:

trisa = %11111111 'set portA-RA1 input
porta = %00000000 'set portA high to give an input sensor


SEN1 :
if portA.0 = 0 then SEN2 'If sensor 1 dont detect then jump to SEN2
if portA.0 = 1 then LCD1 'Sensor at level1 detect then go to LCD 1
goto SEN1

SEN2 :
if portA.1 = 0 then SEN3 'If sensor 2 dont detect then jump to SEN3
if portA.1 = 1 then LCD2 'Sensor at level2 detect then go to LCD2
goto SEN1

SEN3 :
if portA.2 = 0 then SEN1 'If sensor 3 dont detect then jump to SEN1
if portA.2 = 1 then LCD3 'Sensor at level3 detect then go LCD3
goto SEN1

LCD1:

LCDOut$fe,1 'Clear LCD
LCDOut$fe,2 'Position cursor at home

LCDOut "LEVEL 1 HAZARD"
Pause 1000
Goto SEND1

lcd2:

LCDOut$fe,1 'Clear LCD
LCDOut$fe,2 'Position cursor at home

LCDOut "lEVEL 2 HAZARD"
Pause 1000
Goto SEND2

LCD3:
LCDOut$fe,1 'Clear LCD
LCDOut$fe,2 'Position cursor at home

LCDoUT "lEVEL 3 HAZARD"
Pause 1000
Goto SEND3

SEND1:
'Send SMS Test-Message LEVEL 1
HSerout ["ATZ",13,10]
Pause 1000

HSerout ["AT+CMGF=1",13,10] 'Set Text Mode
Pause 500

HSerout ["AT+CMGS=",34,"+01234567890",34,",129",13,10]
Pause 500

HSerout ["LEVEL 1 HAZARD",10,13]
HSerout [26]
Pause 1000
goto SEN1

SEND2:
'Send SMS Test-Message LEVEL 2
HSerout ["ATZ",13,10]
Pause 1000

HSerout ["AT+CMGF=1",13,10] 'Set Text Mode
Pause 500

HSerout ["AT+CMGS=",34,"+01234567890",34,",129",13,10]
Pause 500

HSerout ["LEVEL 2 HAZARD",10,13]
HSerout [26]
Pause 500
goto SEN1

SEND3:
'Send SMS Test-Message LEVEL 3
HSerout ["ATZ",13,10]
Pause 1000

HSerout ["AT+CMGF=1",13,10] 'Set Text Mode
Pause 500

HSerout ["AT+CMGS=",34,"+01234567890",34,",129",13,10]
Pause 500

HSerout ["LEVEL 3 HAZARD",10,13]
HSerout [26]
Pause 1000
goto SEN1

Please someone took a look which part is wrong..

[Ioannis]

For starters I would suggest to use crystal at 8MHz or better at 16MHz EXACTLY. Not 4.5 or other. May be 4MHz would work, but don't recommend it. Too slow. It is important to have correct frequency, otherwise the UART will be out of sync.

Then use these Defines

DEFINE HSER_RCSTA 90h
DEFINE HSER_TXSTA 24h '9600 baud rate, BRGH=1
DEFINE HSER_BAUD 9600
DEFINE HSER_SPBRG 129
DEFINE HSER_CLROERR 1

DEFINE OSC 8 'or 16

What are you trying to do here?

this makes the A port input :trisa = %11111111 'set portA-RA1 input
and this makes the port output (?): porta = %00000000 'set portA high to give an input sensor

Then I see at your code that you send a ATZ to the mobile. Have you checked how long does it take for a mobile to RESET? I found that the Wavecom needs about 17 seconds for the GSM engine to be accessible. In the meantime the AT commands are working OK!!!

First you have to check if the mobile is responding with its name like this:

HSerout ["AT+CGMI",13] 'Get Manufacturer ID
Hserin 1500,err1,[wait("WAV")] 'Wait for Wavecom Module <<<--- Put here the name of your modem!!!
lcdout com,line1,"Module found!"

One trick to succesfully realize that you can send SMS is to check if at the command AT+CMGF=1 the device responds with OK like this:

HSerout ["AT+CMGF=1",13] 'Text SMS mode
HSerin 5000,error,[wait("OK")]

The devices have different respond times for different commands.

You have to check with a terminal programm like Hyperterminal sending AT+ commands. Also always wait for a response from the mobile. Either OK or another character.

Ioannis