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<?xml-stylesheet type="text/xsl" href="https://community.arm.com/utility/feedstylesheets/rss.xsl" media="screen"?><rss version="2.0" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:slash="http://purl.org/rss/1.0/modules/slash/" xmlns:wfw="http://wellformedweb.org/CommentAPI/"><channel><title>Cant interface 8051 with a GSM module</title><link>https://community.arm.com/developer/tools-software/tools/f/keil-forum/24572/cant-interface-8051-with-a-gsm-module</link><description> 
i cant interface NXP2148 with the GSM module. i have used the
UART1 (through RS232 DB9 using RXD, TXD and ground) to interface with
the GSM module at 9600. 
when i send the command AT&amp;lt;CR&amp;gt; through hyperterminal it
accepts, sends back an OK 
when i SEND</description><dc:language>en-US</dc:language><generator>Telligent Community 10</generator><item><title>RE: Cant interface 8051 with a GSM module</title><link>https://community.arm.com/thread/77720?ContentTypeID=1</link><pubDate>Sun, 06 Sep 2009 22:53:20 GMT</pubDate><guid isPermaLink="false">dd9e70c8-6d3c-4c71-b136-2456382a7b5c:4df7f671-95f5-417c-8be4-ce4cd67ca136</guid><dc:creator>kanika jab</dc:creator><description>&lt;p&gt;&lt;p&gt;
i got the problem...&lt;br /&gt;
DTR signal should have been LOW only in my board it is about +9V.&lt;br /&gt;
THANKs A LOT for your help...&lt;/p&gt;
&lt;/p&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;</description></item><item><title>RE: Cant interface 8051 with a GSM module</title><link>https://community.arm.com/thread/89950?ContentTypeID=1</link><pubDate>Fri, 04 Sep 2009 03:50:20 GMT</pubDate><guid isPermaLink="false">dd9e70c8-6d3c-4c71-b136-2456382a7b5c:2abb0059-db7b-49cc-adb9-5456865383be</guid><dc:creator>ImPer Westermark</dc:creator><description>&lt;p&gt;&lt;p&gt;
Andy lists a long list of potential problems.&lt;/p&gt;

&lt;p&gt;
My question is: Have you used an oscilloscope and looked at the
signals on the GSM side? What is the difference when your
microprocessor tries to send to the GSM moden, compared to the case
when you send from Hyperterminal?&lt;/p&gt;

&lt;p&gt;
If you do see a difference, you just have to backtrack to the
source of that difference.&lt;/p&gt;
&lt;/p&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;</description></item><item><title>RE: Cant interface 8051 with a GSM module</title><link>https://community.arm.com/thread/56740?ContentTypeID=1</link><pubDate>Fri, 04 Sep 2009 00:49:23 GMT</pubDate><guid isPermaLink="false">dd9e70c8-6d3c-4c71-b136-2456382a7b5c:3c737507-27c0-42d8-a478-de8d58284cfe</guid><dc:creator>Andy Neil</dc:creator><description>&lt;p&gt;&lt;p&gt;
DO you have a proper RS232 transceiver in place?&lt;/p&gt;

&lt;p&gt;
Are you certain that the cable connections are correct?&lt;br /&gt;
Remember that the modem is a DCE, and TX is an &lt;i&gt;&lt;b&gt;input&lt;/b&gt;&lt;/i&gt; on
a DCE...&lt;/p&gt;

&lt;p&gt;
Does the modem require any/all of the modem control lines (RTS,
CTS, etc)? If so, have you correctly implemented them.&lt;/p&gt;

&lt;p&gt;
&lt;i&gt;&amp;quot;when i SEND the same command through NXP2148 there is no
response.&amp;quot;&lt;/i&gt;&lt;/p&gt;

&lt;p&gt;
That could be any number of things:&lt;/p&gt;

&lt;p&gt;
1. The MCU is not sending at all;&lt;/p&gt;

&lt;p&gt;
2. The MCU is sending, but it is not (quite) right;&lt;/p&gt;

&lt;p&gt;
3. The signal is not reaching the DCE;&lt;/p&gt;

&lt;p&gt;
4. The signal is reaching the DCE, but it&amp;#39;s not listening;&lt;/p&gt;

&lt;p&gt;
5. The DCE is receiving the signal, but it is ignoring it;&lt;/p&gt;

&lt;p&gt;
6. The DCE is responding, but the response is not reaching the
MCU;&lt;/p&gt;

&lt;p&gt;
7. The response is reaching the MCU, but your software is not
(correctly) recognising it&lt;/p&gt;

&lt;p&gt;
&lt;i&gt;etc, etc,...&lt;/i&gt;&lt;/p&gt;
&lt;/p&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;</description></item></channel></rss>