Pic to GSM Phone connection (HSerin problems)

[Rufinus]

Here is the code i used to test it with PC:

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



'Main program


pause 1000 'wait for screen to sort get started
start:
lcdout $FE,1, "Sending number.."
pause 1000
HSEROUT ["atd **********", 13, 10]
HSERIN [wait("OK")]


lcdout $FE, 1, "Got it!"
pause 1000
goto start
end


It's running on 16f870 connected trough max232 to com2 port on pc, and i have no problem!
When i connect the phone following way:
PIC--->MAX232--->Data cable (original Siemens)--->Phone

Nothing happens!
That must be the cable. But from other side, phone is listening to commands from pc, using same cable with only 3 wires connected: Rx, Tx, GND
Miricle..

[Ioannis]

'Main program

pause 1000 'wait for screen to sort get started
start:
lcdout $FE,1, "Sending number.."
pause 1000
HSEROUT ["atd **********", 13, 10]
HSERIN [wait("OK")]

lcdout $FE, 1, "Got it!"
pause 1000
goto start
end

Try to add on top of your program:

HserOut ["AT",13,10] ;Sync modem to 9600 baud

Also if you power up PIC at the same time as the mobile you won't get reliable connection with the phone until the phone is on the network.

Ioannis

[Rufinus]

Thanx, but i tried this already. Nothing. And i do not power up the phone in the same time. Phone is just on costantly.

I thougt, maybe when i send AT, phone answers OK, but pic does not capture it (for whatever reason). So i changed to atd **********, because even if pic is not capturing the answer, phone should react (dial given number).
I started yesterday to build new cable, just typical 3 wires based on standard MAX232. Let's see what this will give. I will test it with the phone--->pc connection first, and than test with pic. And if this doesnt work, i should consider direct connection from pic to phone without max232 but just trough 1 kOhm resistors. Shall i send in inverted mode then?

And i measured voltages on the original cable, both form the phone's side and rs232 side. Cable was pluged in the phone and not in rs232. I can give them here, if somebody is interested. It seems, that phone is powering the cable's logic.

[Ioannis]

If you miss the MAX232 then send in inverted mode. The MAX does this inversion.

Another thing you may try is to use Numeric mode instead Alphanumeric. Then the phone answers 0 (zero) for OK, 4 for error etc.

Did you double check that you have not connected Rx, Tx the wrong direction? Try to cross connect them. Don't worry, RS232 is able to withstand this if it wrong.

Ioannis

[Rufinus]

OK, i will try again without MAX using inverted mode. How to set it in HSerout command?
I am sure about the RX TX connection, besides, with the pc communication there are no problems.
And i will try also numeric mode (atv0, if i am corect?)

Well, it would be easy to give up on it, but it looks like nobody tried yet with Siemens. And anyways i like doing this things, so i will keep on going untill its working anyhow, and than i will try to get it working with original cable (sometimes i am an optimist )

Thanx for your help, Ioannis, i appreciate it.


P.S. I have a feeling, that this must be some stupid little ditail which is missing. As allways, so..

[Ioannis]

On the matter of Rx Tx connection let me insist on. Try to change and see what happens.

Also with siemens (cannot recall the model) had no problem 2-3 years ago.

Whatever you connect to the PIC as modem and sending "AT" it should reply "OK".

Ioannis

[NavMicroSystems]

Rufinus,

I guess the problem is with the Siemens Datacable.
Most cables have some embedded electronics.
(At least a level shifter, probably more..)

This is usually powered from the PCs serial port (DTR & RTS)
So if you are using one of these cables to connect the phone you will need a MAX232 on the PIC end as well.
And you have to set the correct levels at DTR & RTS on the MAX232 at the PIC end in order to supply the cables embedded electronics.

As far as I can remember The Siemens interface is 5V tolerant, so all you need is 3 straight wires from the PIC to the Phone (no MAX232 at all).
But then you'll have to use SERIN2 /SEROUT2 instead of HSERIN/HSEROUT since HSERIN/HSEROUT doesn't allow to toggle between true/inverted mode.

[Rufinus]

OK, just finished selfmade cable.
Rx and Tx do through the MAX, and CTS(5), RTS(6), DCD(7) are connected to the GND(2) trough 10k resisors. Without this it does not work. Or other way is to connect RTS to CTS straigt, it will communicate with the PC then also. Communication with the PC was fine in both cases. So, sefmade cable is considered to work correctly, at least for the AT commands.

Tried swapping Rx and Tx as Ioannis sugested, but it just made my phone to go off. After restart it was working fine. So, nothing was wrong with my pinout.


Now, NavMicroSystems, i am not that sure about powering cable from COM port. It is rather powered by the phone itself (as strange as it sounds). As a proof i can say, that i was able to communicate with the PC, using original cable with only 3 wires (Rx, Tx, GND), rest of them i disconnected for the experimental sake. And in this configuration it was working with hyperterm or some similar software except original Siemens software, which did not detect the phone. Only when you connect also CTS line, the phone will be detected by the Siemens software.

I should mention again, i'm experimenting on S65 and S55 phones which are rather new, and they are different from older Siemens models, pinout of the phone's interface and connector itself are different.


So, now my setup looks like this: PIC--->MAX232--->MAX232(selfmade cable)--->Pnone

From above, and as NavMicroSystems says, both MAXes can be ommited. Will try then connecting straight PIC to Phone using serout2 in inverted mode.
Wish me good luck