Modem Auto Answer-Hanging for 1 min...

[Luciano]

Download this free terminal program and try the
modem with the serial port of your PC.
(Just 3 wires, RX,TX,GND)

The program is only an EXE file, no setup.

With this program you can create 12 macros.

Example of macro:

AT#013#010
This will send AT and "CR" + "LF" (cariage return + line feed)

Terminal program home page:
http://bray.velenje.cx/avr/terminal/

File download link:
http://bray.velenje.cx/avr/terminal/dl.php

Luciano

[Ioannis]

Hi!

The problem is not with the modem. It is with the PIC code executing up to a point then stops for a minute or so and then resumes.

No interrupts or other source is envolved. The problem is on the 3 Hserout. If the 3 becomes 1 OR the LOCATION of the code changes, then it executes normally.

This is the problem!

I do not have to wait for the modem to respond. I just wait and give next command after a while.

I believe it is a problem related with the "code crosses boundary @ ..." that shows up 3 times since the code is long enough.

Ioannis

[Luciano]

Hi,

I went quickly through your code.

What you can read here is based on what I understand from
the PicBasic Pro manual and the 16F877 datasheet.
(Not tested with real hardware and software).

==================================

DEFINE HSER_CLROERR 1

If you use "DEFINE HSER_CLROERR 1", PicBasic Pro
will generate the code that in background will take
care of the FIFO RX buffer overrun error. When you
send the AT commands with HSEROUT, the modem will
respond after each single AT command with "OK".
(In your case "0" + CR because of the use of "ATV0").
So while you send the second or third AT command, the
response of the modem to the first or second AT command
will cause an overrun error and therefore the background
code will be executed, which could be the cause of the problem.


What happen with your code:
(From the file you have previously attached).

i=rcreg:i=rcreg

Here you get (clear) the two bytes from the FIFO buffer.



HSerout ["ATV0",13]'Set Numeric Response

The modem sends back 2 bytes. (Ascii 48 and 13).



HSerin 250,no_modem,[i] 'Wait for 0 "zero" (OK)

You read the first byte (Ascii 48) of the two bytes
waiting in the FIFO but one byte will remain in the FIFO.



Hserout ["ats0=2",13,10]
pause 500

The modem sends back the 2 bytes response (Ascii 48 and 13)
and while the UART receives the second byte the overrun error
will occur. (One byte was already there before sending the AT
command so 1+2=3 and with 3 you get the overrun error).
The background code is executed to clear the error. At this
point the FIFO is full.(Two bytes).


hserout ["ATX3",13,10]
pause 500

The modem sends back the first byte of the two bytes response,
(Ascii 48 and 13) and while the UART receives this first byte
the overrun error will occur.
(Two bytes were already there before sending the AT command so
2+1=3 and with 3 you get the overrun error). The background
code is executed to clear the error. After the overrun error
is completed, the execution of your program will resume with the
next statement which is Hserout ["AT&K0",13,10]. The execution
will be interrupted by the overrun error caused by the second byte
of the previous modem response.


Solution 1:

Keep "DEFINE HSER_CLROERR 1" but use a longer pause
between the single AT commands and read the modem
response from the double buffered register RCREG.
This will ensure that the two bytes RX FIFO buffer is
empty before you send the next AT command.


Solution 2:

Remove "DEFINE HSER_CLROERR 1".

In order to be able to receive data in the UART you
will have first to manually clear the overrun error with:

RCSTA.4 = 0
RCSTA.4 = 1

================================

* * *

================================

Also a possible improvement:

Remove this line from your code.

DEFINE HSER_BAUD 9600
(Replaced by the 3 lines below).

Make sure these 3 lines are in your code.

DEFINE HSER_RCSTA 90h
DEFINE HSER_TXSTA 24h
DEFINE HSER_SPBRG 129 ' 9600 Bauds, error 0.16%

================================

* * *

================================

Small format errors:

SUB "continue"
pause 15000: (remove the colon : at the end of the line)

SUB "com_device"
i=rcreg:i=rcreg: (remove the last colon : at the end of the line)

================================

* * *

================================

Also a possible improvement:

In your code I see that you use everywhere only CR
after each AT command. Why do you use CR + LF now?

Is ATZ the right AT command?

ATZ means to reset the modem to the settings stored
by the user. You usually have at least one set of
registers for the user to customize their modem with.

AT&F means to reset the modem to the factory default settings.

A few modems take a moment to finish doing an AT&F and
may ignore the next thing sent to them, though not many.
Many will take quite a while to complete an ATZ, and will
ignore the next things sent to them. You really have to
wait for an OKAY response from the modem, before
doing anything after an ATZ or AT&F.
================================

* * *

Best regards,

Luciano

[Ioannis]

Luciano, thank you for your extensive reply. The corrections were made, ok.

As for the main problem, it has nothing to do with the external device. It's something related to the sub handling from PBP. Look at the following response taken from the Terminal program suggested earlier:

ATE0
ATV0 <-- at this point I am sending a 0 from the terminal
ats0=2 <-- response is as expected from the program
ATX3 <-- again as expected
AT<00> <-- upto this point, were the command freezes!
<-- then after a minute the <00> appears and execution
continues normally!

AT+CMGF=1
ATS37=9
ATS40=2

So the problem is inside the UART of the PIC as it may look...

Ioannis

[Bruce]

If you disconnect the modem, and just monitor serial data the PIC is sending, what results do you get?

[Luciano]

Hello,

My theory was wrong.

Bruce in the post #13 there is no modem connected.

The post #13 as I understand it:

The PIC sends "ATE0" to the RX pin of the PC. (The terminal program of the PC shows ATE0).

The PIC sends "ATV0" to the RX pin of the PC. (The terminal program of the PC shows ATV0).
Ioannis types "0" in the terminal program of the PC and the PIC gets this byte
otherwise no further AT commands are sent by the PIC.

The PIC sends "ats0=2" to the RX pin of the PC. (The terminal program of the PC shows ats0=2).

The PIC sends "ATX3" to the RX pin of the PC. (The terminal program of the PC shows ATX3).

The PIC sends "AT&K0" to the RX pin of the PC, but the PC terminal program shows only
AT and after a minute in addition to AT the PC receives also <00>. So after a minute
on the PC screen you will see AT<00> and the execution of the program continues normally
in the PIC. (So the PIC does not successfully send AT&K0 to the PC).

Ioannis please confirm that.

Luciano

[Ioannis]

Luciano yes. You are right. This is exactly the case. Bruce, sorry, in #13 I did not clearly stated that the device was disconnected.

Please also note that, if all the 3 Hserin commands are joined as one then there is NO problem in the transmitted string! (I do not know if there is other problem in some other subroutine though...)

So, as I can conclude up to this moment, there must be some difficulty from PBP to work with many and some long sub routines.

Also, if the subrounines are transfered from the top to the bottom then this problem disappears! (Others from other sub's are appearing then...)

Black Magic or what?

Ioannis