BGS2T AT Command Set
1.5 Communication between Customer Application and BGS2T
BGS2T_ATC_V01.301
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1/31/12
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1.5
Communication between Customer Application and BGS2T
After power-up or restart ensure that the ME is in ready state before trying to send any AT command or data. For
detailed information on timing conditions, signal states and particularly the startup behavior of the BGS2T's sig-
nal lines refer to the Hardware Interface Description
.
Leaving hardware flow control unconsidered the Customer Application (TE) is coupled with the BGS2T (ME) via
a receive and a transmit line.
Since both lines are driven by independent devices collisions may (and will) happen. For example, if the TE
issues an AT command and the BGS2T starts sending a URC. This will probably cause the TE to misinterpret
the URC being part of the AT command's response. To avoid this conflict the following measures must be taken:
•
If an AT command is finished (with "OK" or "ERROR") the TE shall always wait at least 100 ms before sending
the next one. This applies to bit rates of 9600 bps or higher (see
). At bit rates below 9600 bps the
delay must be longer: 300 ms at 1200 bps, and 500 ms at 300 bps.
The pause between two AT commands gives the BGS2T the opportunity to the transmission of pending URCs
and get necessary service.
•
The TE shall communicate with the BGS2T using activated echo (
1), i.e. the BGS2T echoes characters
received from the TE.
Hence, when the TE receives the echo of the first character "A" of the AT command just sent by itself it has
control both over the receive and the transmit paths.
Using Backspace at command line:
•
As the standard GSM alphabet does not provide a backspace functionality the BGS2T is designed to use the
character "08" (hex 0x08) as backspace for command line input. This allows the user to easily erase the last
character when writing an AT command. On the other hand, this solution requires entering the escape
sequence \08 for writing the "ò" character in GSM character string parameters.
•
If command echo is enabled (
1) Backspace may cause 08 - 32 - 08 (decimal) character sequence or no
echo, depending on serial interface and speed of character input.
Software flow control:
•
Regardless of the selected alphabet, keep in mind that, when using software flow control (
1), character
values 17 and 19 (decimal) are interpreted as XON/XOFF control characters.
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