Little serial confusion

arno · 2006-06-02 06:30

Hello,
Sorry for this simple question but how did you define if you have to invert or dontInvert a serial signal ?

I have some problem to make my Javelin talk to a GSM/GPS Siemens XT55

It's look like they can't talk together, and I can't figure out Why.
I try all kind of config and nothing happen. The module is on, and by default it's in autobaud mode.

but I send an AT then an AT+PIN and I have no error code back and no connection to the GSm.

I try to connect a PC in parallel of the TX (from the GSM) and at 9600, N, 8, 1 (same as the javelin config) I have a bunch of code but can't find what speed or config it is.

Any clue on how to debug this ?

thanks in advance,
arno

Peter Verkaik · 2006-06-02 08:15

static final int txPin = CPU.pin0;
static final int rxPin = CPU.pin1;

You define a transmit uart as

Uart tx = new Uart(Uart.dirTransmit,txPin,Uart.dontInvert,Uart.speed9600,Uart.stop1);
or
Uart tx = new Uart(Uart.dirTransmit,txPin,Uart.invert,Uart.speed9600,Uart.stop1);

You define a receive uart as

Uart rx = new Uart(Uart.dirReceive,rxPin,Uart.dontInvert,Uart.speed9600,Uart.stop1);
or
Uart rx = new Uart(Uart.dirReceive,rxPin,Uart.invert,Uart.speed9600,Uart.stop1);

Note that the javelin has TTL level signals (0/5V).
To convert to RS232 level signals (-10/+10V), use the COM connector on the javelin demoboard
or connect a level shifter like max232 to the javelin.

regards peter

arno · 2006-06-02 08:21

well here it what i use:

final static int GSM_RX_PIN = CPU.pin1; // DB9 pin 3
final static int GSM_TX_PIN = CPU.pin2; // DB9 pin 2
final static int GSM_POWER_PIN = CPU.pin3; // DB9 pin 3

// GSM serial init, IN and OUT
static Uart rxGSM = new Uart( Uart.dirReceive, GSM_RX_PIN, Uart.invert,
Uart.speed9600, Uart.stop1 );
static Uart txGSM = new Uart( Uart.dirTransmit, GSM_TX_PIN, Uart.invert,
Uart.speed9600, Uart.stop1 );

// GSM init (power, on, PIN code, wait for GSM network
CPU.delay(21); //21*98.5usec= ~20msec after power up
CPU.writePin(GSM_POWER_PIN, true);
if ( DEBUG )
System.out.print("GSM on\n\r");
CPU.delay(205); //205*98.5usec= ~200msec
CPU.writePin(GSM_POWER_PIN, false);
// wait form GSM on
CPU.delay(32767);
CPU.delay(32767);
CPU.delay(32767); //total 9.68 sec
txGSM.sendString ("AT+CPIN=9878\r");
if ( DEBUG )
System.out.print("PIN code send\n\r");
CPU.delay(32767);
if ( ReadGsm() > 0 ) {
if ( DEBUG )
Format.printf( "PIN error: %s\n\r", GSMcode.toString() );
}
else if ( DEBUG )
System.out.print( "PIN OK\n\r" );

// Read any GSM messages
// return 0 if OK, and > 1 if code -> and data stored into Code
private static int ReadGsm() {
while ( rxGSM.byteAvailable() ) {
GSMbyte = (char)rxGSM.receiveByte();
if ( GSMbyte == CR || GSMbyte == LF ) // remove any CR/LF code
continue;
GSMdata.append( GSMbyte );
}

if ( ! GSMdata.equals( "OK" )){
GSMcode.clear();
GSMdata.subString( 1, GSMdata.length()-1, sbuf );
GSMcode.append( sbuf.toString() );
return GSMcode.length();
}
return 0;
}

but that dosen't help !!!

I still don't have anue clue in when you should use invert and when donInvert (at least this point)

but thanks for looking into my problem

Peter Verkaik · 2006-06-02 09:13

I added some extra debug statements to your code.
What exactly is your output with this program?
Do you have any manual for your GSM?

regards peter

arno · 2006-06-02 09:29

Well the output of this program is just an empty string after the error messages
so It can be a code that can't be displayed.
Good idea to put in hexa.

Yes I do have all the manual for it, 2 tine 2.5 meg (the hardware guide and the AT code set)

Thanks for your input I will try it

is the t.timeout better than the CPU.delay ? (it's look like the timeout is based on msec and the delay is in 98.5 usec)

why did you do thta:
if ( ((GSMbyte&0xFF) == CR) || ((GSMbyte&0xFF) == LF) )

since CR and LF hare decimal code and this (char)rxGSM.receiveByte() return a decimal value no ?

arno · 2006-06-02 09:35

I just send you an email with the manual and the full code

Peter Verkaik · 2006-06-02 09:41

Both char/byte and int take 2 bytes in memory,
the exception is array of char/byte (1byte per element)
By ANDing with 0xFF I make sure there is no sign extend to
the higher byte. I therefore always use int for simple variables.
I use char only in char array. Note that the uart receive returns
an int with its high byte cleared.

regards peter

Peter Verkaik · 2006-06-02 10:00

From the manual page 55 chapter 3.9.3 I Tablee 14 I read

Table 14: DCE-DTE wiring of 2nd serial interface (GSM/GPRS part)
[font=Arial,Bold size=2]V.24 DCE (XT55) DTE (application)
circuit Pin function Signal direction Pin function Signal direction
[/font]103···· GSM_TXD1··· Input·················· /TXD············ Output
104···· GSM_RXD1·· Output················ /RXD············ Input
105···· GSM_RTS1·· Input·················· /RTS············ Output
106···· GSM_CTS1·· Output··············· /CTS············· Input

It looks you must use the 2nd serial interface for AT control, using the pins /TXD /RXD /RTS /CTS.
These pins have RS232 level signals (V24).
you need to connect these pins through a level shifter to the javelin.
You can make a local handshake by connecting /RTS to /CTS,
or use the javelin Uarts with handshake.
If you use the javelin demoboard then you can use its onboard level shifter.
Otherwise you need to use an external levelshifter like MAX232.

Do you have a schematic how you connected the javelin to your gsm?

regards peter

arno · 2006-06-02 10:22

I use port 0 not the port 1
and it is a straigth connexion, no level convert
And I didn't implemet flow control neither hardware or woftware.

And on page 54:
interfaces conforming to ITU-T V.24 protocol DCE signaling. The electrical characteristics do
not comply with ITU-T V.28. The significant levels are 0V (for low data bit or ON condition)
and 2.65V (for high data bit or OFF condition). For electrical characteristics please refer to
Table 38. Figure 1 shows the serial interfaces of the XT55 module.

So if the javelin is doing 0 and 5v, maybe my 2.65v is to low for it.But can I do just 5v with the MAX converter or is it +-12v ?

Peter Verkaik · 2006-06-02 12:28

Yes I see.
2.65V should be suffient for the javelin to see it as a logic 1
(the javelin logic has 2.5V treshold, so voltage<2.5V is logic 0 and voltage>2.5V is logic 1).
Question is if the 5V that the javelin outputs is not too high for the gsm
(it would if the gsm operates at 3.3V)

But lets assume you are right.
Port 0 pins for data:
GSM_TXD0 then connects to the javelin uart transmit pin
GSM_RXD0 then connects to the javelin uart receive pin
for handshake:
GSM_CTS0 then connects to the javelin uart transmit handshake pin
GSM_RTS0 then connects to the javelin uart receive handshake pin
or make local handshake by connecting GSM_CTS0 to GSM_RTS0
Normally in modem connections DTR is monitored for connected devices.
GSM_DTR0 then connects to javelin pin for ON/OFF

The table 14 shows pin functions as inverted (/ in front of TXD0)
so it maybe you must use Uart.invert in your uarts.
The one thing that is different between your setup and the above, is the
local handshake between RTS and CTS. If you do not have this, and your
gsm communication parameter setup has RTS/CTS handshake enabled, then
it may be the gsm is waiting for a logic low at pin GSM_RTS0.

If you have the javelin pins to spare, I suggest using uarts with handshaking, for now,
until you got the communication going.

regards peter

arno · 2006-06-02 12:50

Yes the GSM operate at 3.3V, so I will put a resistor in middle and use the hardware handshake to see if that help.

Thanks for your help/advise

regards,

arno

Peter Verkaik · 2006-06-02 12:59

I hope the gsm input pins are then 5V tolerant (they usually are).

You could make a resistor divider for javelin pins that are outputs
to the gsm pins that is an input.

javpin output ·

[noparse][[/noparse]3k3]-+

gsm pin input
··························|
························[noparse][[/noparse]6k8]
························· |
·························-+- 0V

That turns 5V into 3.3V

regards peter

Peter Verkaik · 2006-06-02 13:13

Description of TX55 evaluation board:
http://www.mcs-nl.com/files/nl/m2m/siemens/xt55/gsm_gps_eval_board_v01.pdf
regards peter

Peter Verkaik · 2006-06-02 13:28

Firmware update manual, has serial schematic for mmi processor (figure 5, page 10).
http://www.wdm.se/alla/XT55/Application%20Notes/xt55_an_16_fw_update_v06.pdf
Figure 6 shows PC interface!
regards peter

Peter Verkaik · 2006-06-02 15:48

From the firmware update manual schematic,
it looks like the module is powered on
when /IGT pin is set to low.
In that schematic a transistor is used to pull the /IGT pin low.

You can use a javelin pin directly.
Make the pin a low output·and \IGT gets pulled low.
Make the pin an input and \IGT becomes HiZ.

So, to power on:
··· CPU.writePin(GSM_POWER_PIN, false);
to power off
··· CPU.setInput(GSM_POWER_PIN);

regards peter

Post Edited (Peter Verkaik) : 6/4/2006 8:20:46 AM GMT

arno · 2006-06-05 09:08

Hello,
So I did many change of my code. (thanks Peter for your idea)
Actually the Javelin was talking to the GSM but due to some error (or misunderstanding) of the output of the GSM I wasn't able to handle correctly the return. (the GSM has the local echo turn on, and I didn't expect that, no I turn it on at the begining)
So I did some cleaning of my ReadGsm function, but maybe to mutch !!
It was working until I enter the PIN code to my gsm, the GSM give me an error 4 (operation not allowed) but that's because the PIN code wasn't need (maybe,never have the chance to test without it).
So I handle a little more about the error return (this line: if ( !GSMdata.equals("ERROR") ))

and know for what ever reason the Javelin go to the first 10-15 line the loop forever where their is no loop in my code, and sometime gos out with a indexOutofBounds exception or somthing like that (in string Buffer, but when the program crash I did't call it yet).

so here is the ourput of my terminal:
GSM on
GSM on
end delay 1
GSM on
end delay 1
GSM on
end delay 1
GSM on
end delay 1
GSM on
GSM on
GSM on
and going and going.

what the heck is that ?!? whiy is he looping like that ?

any clue/helpwill be greatly appreciate.

I attached the cade also.
maybe not the best I write but I thuink anybody can read it.

Peter Verkaik · 2006-06-05 09:45

After the last line in your main(),
add the line
· while (true) ;

This keeps the javelin alive doing nothing.
Without it, main() exits and probably restarts, but that is undefined.

regards peter

Peter Verkaik · 2006-06-05 09:57

According to the output, the javelin resets in Initialize().
I noticed you use CPU.writePin(GSM_POWER_PIN,true)
to turn off the gsm.
According to schematics the gsm is powered of if GSM_POWER_PIN is floating.
It may be that driving that pin high creates a voltage dip which may
result in the javelin's ·reset. The javelin is quite sensitive to power supply
ripple.

regards peter

Peter Verkaik · 2006-06-05 10:04

Your CPU.delay(21) must be CPU.delay(210) for a 20 msec delay
in Initialize().
regards peter

arno · 2006-06-05 10:22

Thanks for the 2 inputs.

CPU.delay I change it, so now I realy wait 20ms

GSM_POWER_PIN is active low, and regading the Manual I sould left it open or HiZ, how can I do that ? should left it low after m power on procedure ?

Style the same result, actually I just got 1 time the GSM on messages then 3 time a messages main start (just a system.ou.println I had as a first line in main procedure.

more clue for me ?

Peter Verkaik · 2006-06-05 10:22

It most likely is a generated bytecode sequence that is misinterpreted.
Capture the start of Initialize in try/catch like

··· try {
··· GPSstate = NP_STATE_SOM;· // Ready to take commande '$' on GPS
··· GSMcmd.clear();
··· GSMdata.clear();

··· // GSM init (power, on, PIN code, wait for GSM network
··· CPU.delay(21); //21*98.5usec= ~20msec after power up
··· CPU.writePin(GSM_POWER_PIN, true);
··· GSMPower = false;
··· if ( DEBUG )
····· System.out.print("GSM on\n\r");
··· CPU.delay(2000); //2000*98.5usec= ~197msec
··· CPU.writePin(GSM_POWER_PIN, false);
··· GSMPower = true;
··· GSMstate = GSM_STATE_ON;
··· GSMstatus = GSM_STATUS_ON;
··· // wait form GSM on
··· CPU.delay(32767);
System.out.println("end delay 1");
··· CPU.delay(32767);
System.out.println("end delay 2");
··· CPU.delay(32767);· //total 9.68 sec
··· }
··· catch (Exception e) {
····· Format.printf("Init exception\n");
··· }

That sometimes resolves these kind of errors.

regards peter

arno · 2006-06-05 10:24

oup sorry find the answer about the hiz stuff in a post before:
CPU.setInput(GSM_POWER_PIN);

I will do that

Peter Verkaik · 2006-06-05 10:25

Use CPU.setInput(GSM_POWER_PIN) to make the pin floating.
It may be that setInput() is still private in class CPU.
Then just make it public. Disable the readonly property
of the CPU.java file before editing the file.
regards peter

arno · 2006-06-05 10:43

So I'm an idiot !!
The probleme come from my power suplly, dosen't handle the load !!
So the power come down to 4.5 volts and the Javelin do reset itself jst when the GSM start !!!

Rhaaaa that unacceptable.

So I change it and now I have :
GSM on
main start
GSM on
end delay 1
end delay 2
call readgsm
Start while
End while

So the problem is on myReadGsm loop during the test of the answer from my GSM.
if ( GSMdata.indexOf("OK") == -1 || ! GSMdata.equals("0") ) { // the GSM can answer the ok in 2 form OK or 0
if ( !GSMdata.equals("ERROR") ) { // if I have the error messages in it treat it
GSMret = GSMdata.indexOf(":");
GSMdata.subString( GSMret+1, GSMindex-GSMret+1, GSMcode );
}
return 1; // if error code just return 1 and the error messages into GSMcode. The error can be: ERROR or +CME ERROR: bla bla bla
}
return 0; // If OK (or 0) just return with value 0
Actually I have some proble to figure out what I need to do !!
The answer can be:
OK (or 0) if everything is in order
ERROR (undefine error)
+CME ERROR: bla bla bla
+atcommand (like +CREG:bla bla bla, network registration) the answer to a request, and I'd like to have the bla bla bla copy into the GSMcode
^atcommand to (like at^SMGR read sms fromstorage) treat like a +atcommand

can you give me some hint ? the return code has to be 0 for the ok, and 1 (or more) for an error or a command with answer

Peter Verkaik · 2006-06-05 11:20

Put the following lines just before your error code:

··· Format.printf("GSMdata in hexbytes\n");
··· for (int k=0; k<GSMdata.length(); k++) {
····· Format.printf("%02x ",GSMdata.toString().charAt(k)&0xFF);
··· }
··· Format.printf("\n");

It displays all the GSMdata bytes in hexvalues.
Then you know what you receive as response.

regards peter
·

arno · 2006-06-05 11:26

here is the output:
main start
GSM on
Start while
End while
GSMdata in hexbytes

then crash with
IndexOutofBoundException in StringBuffer

Peter Verkaik · 2006-06-05 11:28

Also, I would not discard any byte, even if non-printable,
before knowing exactly what is returned.

// Read any GSM messages Len is the· At command len
// return 0 if OK, and· 1 if code -> and data stored into Code
· private static int ReadGsm2() {
··· GSMdata.clear();
··· GSMcode.clear();
··· GSMindex = 0;
System.out.println( "Start while" );
··· while (· rxGSM.byteAvailable() ) {
····· GSMbyte = (char)rxGSM.receiveByte();
//····· if( GSMbyte < 0x20 ) // if not printeable char or CR/LF forget it
//······· continue;
//····· if ( DEBUG )
//······· Format.printf( "GSMbyte: %c\n\r", GSMbyte );
//····· GSMindex++;
····· GSMdata.append( GSMbyte ); //·store to GSMdata
··· }
System.out.println( "End while" );

··· Format.printf("GSMdata in hexbytes\n");
··· int k=0;
··· while (k<GSMdata.length) {
····· Format.printf("%02x ",GSMdata.toString().charAt(k++)&0xFF);
··· }
··· Format.printf("\n");
··· if (GSMdata.length > 0) {
····· if ( GSMdata.indexOf("OK") == -1 || ! GSMdata.equals("0") ) {
······· if ( !GSMdata.equals("ERROR") || ! GSMdata.equals("ERROR:") ) {
········· GSMret = GSMdata.indexOf(":");
········· GSMdata.subString( GSMret+1, GSMindex-GSMret+1, GSMcode );
······· }
······· return 1;
····· }
··· }
··· return 0;
· }

regards peter

Post Edited (Peter Verkaik) : 6/5/2006 11:42:33 AM GMT

arno · 2006-06-05 11:44

Many thing come out:
main start
GSM on
Start while
End while
GSMdata in hexbytes
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 F8
AT send
Start while
End while
GSMdata in hexbytes
41 54 0D 0D 0A 4F 4B 0D 0A
AT OK
ATE0 send
Start while
End while
GSMdata in hexbytes
41 54 45 30 0D 0D 0A 4F 4B 0D 0A
ATE OK
AT+COPS=0
Start while
End while
GSMdata in hexbytes
0D 0A 4F 4B 0D 0A
GSM auto reg OK
AT+CREG=1
Start while
End while
GSMdata in hexbytes
0D 0A 4F 4B 0D 0A
GSM registering OK
AT+CREG?
Start while
End while
GSMdata in hexbytes
0D 0A 2B 43 52 45 47 3A 20 31 2C 30 0D 0A 0D 0A 4F 4B 0D 0A
AT^ssync=1
Start while
End while
GSMdata in hexbytes
0D 0A 4F 4B 0D 0A
SYNC OK
AT+CMGF=1
Start while
End while
GSMdata in hexbytes

Peter Verkaik · 2006-06-05 11:46

I just checked the StringBuffer class.
The original StringBuffer had an error in the IndexOf().
A corrected version is located here:
http://groups.yahoo.com/group/JavelinCode/files/Javelin%20Stamp%20IDE/lib/java/lang/

The same applies to the String class. Corrected version also there.

regards peter

Peter Verkaik · 2006-06-05 11:53

Ok, now also print printable.

// Read any GSM messages Len is the· At command len
// return 0 if OK, and· 1 if code -> and data stored into Code
· private static int ReadGsm2() {
··· GSMdata.clear();
··· GSMcode.clear();
··· GSMindex = 0;
System.out.println( "Start while" );
··· while (· rxGSM.byteAvailable() ) {
····· GSMbyte = (char)rxGSM.receiveByte();
//····· if( GSMbyte < 0x20 ) // if not printeable char or CR/LF forget it
//······· continue;
//····· if ( DEBUG )
//······· Format.printf( "GSMbyte: %c\n\r", GSMbyte );
//····· GSMindex++;
····· GSMdata.append( GSMbyte ); //·store to GSMdata
··· }
System.out.println( "End while" );

··· Format.printf("GSMdata in hexbytes\n");
··· int k=0;
··· while (k<GSMdata.length) {
····· Format.printf("%02x ",GSMdata.toString().charAt(k++)&0xFF);
··· }
··· Format.printf("\n");
··· Format.printf("GSMdata in ascii bytes\n");
····k=0;
··· while (k<GSMdata.length) {
····· int c =·GSMdata.toString().charAt(k++)&0xFF;
····· if ((c>=32) && (c<=126)) Format.printf("%c",c);
····· else·Format.printf(".");
··· }
··· Format.printf("\n");
··· if (GSMdata.length > 0) {
····· if ( GSMdata.indexOf("OK") == -1 || ! GSMdata.equals("0") ) {
······· if ( !GSMdata.equals("ERROR") || ! GSMdata.equals("ERROR:") ) {
········· GSMret = GSMdata.indexOf(":");
········· GSMdata.subString( GSMret+1, GSMindex-GSMret+1, GSMcode );
······· }
······· return 1;
····· }
··· }
··· return 0;
· }

arno · 2006-06-05 12:17

here it goes:

main start
GSM on
Start while
End while
GSMdata in hexbytes
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 F8
GSMdata in ascii bytes
........................................................................................
AT send
Start while
End while
GSMdata in hexbytes
41 54 0D 0D 0A 4F 4B 0D 0A
GSMdata in ascii bytes
AT...OK..
AT OK
ATE0 send
Start while
End while
GSMdata in hexbytes
41 54 45 30 0D 0D 0A 4F 4B 0D 0A
GSMdata in ascii bytes
ATE0...OK..
ATE OK
AT+COPS=0
Start while
End while
GSMdata in hexbytes
0D 0A 4F 4B 0D 0A
GSMdata in ascii bytes
..OK..
GSM auto reg OK
AT+CREG=1
Start while
End while
GSMdata in hexbytes
0D 0A 4F 4B 0D 0A
GSMdata in ascii bytes
..OK..
GSM registering OK
AT+CREG?
Start while
End while
GSMdata in hexbytes
0D 0A 2B 43 52 45 47 3A 20 31 2C 30 0D 0A 0D 0A 4F 4B 0D 0A
GSMdata in ascii bytes
..+CREG: 1,0....OK..
AT^ssync=1
Start while
End while
GSMdata in hexbytes
0D 0A 4F 4B 0D 0A
GSMdata in ascii bytes
..OK..
SYNC OK
AT+CMGF=1
Start while
End while
GSMdata in hexbytes

GSMdata in ascii bytes

so at least now I can start to handle the return to have what I need: OK, + (or ^) result command, +error and discard the other (00, f8 ), CR/LF

Little serial confusion

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