Decode some data - Teh Forum

<body> <div id="header"> <span class="left"> <span class="back"><a href="lthread_list.php?webtag=DEFAULT"><span class="image mobile_back" title="Back"></span></a></span> <span class="image mobile_logo" title="Beehive Forum Logo"></span> </span> <ul> <li> <a class="reply_all" href="lpost.php?webtag=DEFAULT&reply_to=42633.0&return_msg=42633.1"> <span class="image mobile_reply_all"></span><span class="text">Reply to All</span> </a> </li> <li> <a class="navigation" href="#"> <span class="image mobile_navigation"></span><span class="text">Show messages</span> </a> </li> <li> <a class="main" href="#"><span class="image mobile_menu" title="Menu"></span> </a> </li> </ul> </div> <div class="menu main"> <ul> <li><a href="lthread_list.php?webtag=DEFAULT">Messages</a></li> <li><a href="lpm.php?webtag=DEFAULT">Inbox</a></li> <li><a href="lsearch.php?webtag=DEFAULT">Search</a></li> <li><a href="llogon.php?webtag=DEFAULT">Login</a></li> </ul> </div> <div class="menu navigation"><a href="lmessages.php?webtag=DEFAULT&msg=42633.1">1–10</a></div> <div id="page_content"> <h3 class="thread_title"><a href="index.php?webtag=DEFAULT&amp;msg=42633.1">Decode some data</a> </h3> <div id="messages" data-navigation="42633_1_10_10"> <a name="a42633_1"></a><div class="message" id="message_42633_1"> <div class="message_header"> <div class="message_from"> From: ANT_THOMAS<span class="message_time">25 May 2020 17:41</span> <div class="clearer"></div> </div><div class="message_to">To: ALL<span class="message_count">1 of 10</span><div class="clearer"></div> </div> </div> <div class="message_links"> <a href="lmessages.php?webtag=DEFAULT&msg=42633.1">42633.1</a></div> <div class="message_body"> I've built some wireless temperature sensors which work fine on my current setup, but I'm looking to improve it. Without going into all the boring details, I have some data I need to manually decode.<br /> <br /> This data contains a float, long and char*.<br /> I've figured out the long and char and need to decode the float. Ideally in a bash script since that's how I'm currently working<br /> <br /> Some examples of the payload data and the known actual values.<br /> <br /> Payload : 0, 0, 108, 65, 60, 16, 0, 0, 97, 0<br /> temp=14.75<br /> bat=4156<br /> adr=a<br /> <br /> Payload : 0, 0, 63, 65, 30, 16, 0, 0, 111, 0<br /> temp=11.94<br /> bat=4126<br /> adr=o<br /> <br /> Payload : 0, 0, 157, 65, 98, 19, 0, 0, 98, 0<br /> temp=19.62<br /> bat=4962<br /> adr=b<br /> <br /> Payload : 0, 0, 144, 65, 208, 17, 0, 0, 108, 0<br /> temp=18.00<br /> bat=4560<br /> adr=l<br /> <br /> <br /> And my decoding so far of the first example<br /> <br /> Payload : 0, 0, 108, 65, 60, 16, 0, 0, <strong>97, 0</strong><br /> char = adr = <strong>a</strong><br /> <br /> Payload : 0, 0, 108, 65,<strong> 60</strong>, <strong>16,</strong> 0, 0, 97, 0<br /> long 8bit to 16bit<br /> (<strong>16 </strong>x 256) + <strong>60 </strong>= <strong>4156</strong><br /> bat=<strong>4156</strong><br /> <em>edit - made an error here</em><br /> <br /> Payload : <strong>0, 0, 108, 65</strong>, 60, 16, 0, 0, 97, 0<br /> I need to decode this to the temp <strong>14.75</strong> float value.<br /> <br /> Any ideas?<div class="edit_text">EDITED: 26 May 2020 10:53 by ANT_THOMAS</div> </div> <div class="message_footer"> <div class="message_footer_links"><a href="lpost.php?webtag=DEFAULT&reply_to=42633.1&return_msg=42633.1" class="reply"><span class="image post"></span>Reply</a></div> <div class="message_vote_form" data-msg="42633.1"> <span class="rating">0/0</span> <span class="image vote vote_down vote_down_off" title="Vote Down"></span> <span class="image vote vote_up vote_up_off" title="Vote Up"></span> </div> </div> </div><a name="a42633_2"></a><div class="message" id="message_42633_2"> <div class="message_header"> <div class="message_from"> From: Peter (BOUGHTONP)<span class="message_time">26 May 2020 10:12</span> <div class="clearer"></div> </div><div class="message_to">To: ANT_THOMAS <span><span class="image post_read" title="Read: 26 May 2020 10:52"></span></span> <span class="message_count">2 of 10</span><div class="clearer"></div> </div> </div> <div class="message_links"> <a href="lmessages.php?webtag=DEFAULT&msg=42633.2">42633.2</a> In reply to <a href="lmessages.php?webtag=DEFAULT&msg=42633.1#a42633_1" target="_self">42633.1</a></div> <div class="message_body"> What makes you think the 65 in position 4 should be used for both <var>bat</var> and <var>temp</var>? <p>And how certain are you of those example numbers? </p><p>Because 144 = 18 * 8 - which seems very coincidental, especially combined with 157 / 8 giving 19.625, but that doesn't work for the first two examples... </p><p>However, 14.75 * 8 is 118 - a single digit out. I don't see anything similar for 11.94 and 63</p></div> <div class="message_footer"> <div class="message_footer_links"><a href="lpost.php?webtag=DEFAULT&reply_to=42633.2&return_msg=42633.1" class="reply"><span class="image post"></span>Reply</a></div> <div class="message_vote_form" data-msg="42633.2"> <span class="rating">0/0</span> <span class="image vote vote_down vote_down_off" title="Vote Down"></span> <span class="image vote vote_up vote_up_off" title="Vote Up"></span> </div> </div> </div><a name="a42633_3"></a><div class="message" id="message_42633_3"> <div class="message_header"> <div class="message_from"> From: ANT_THOMAS<span class="message_time">26 May 2020 10:52</span> <div class="clearer"></div> </div><div class="message_to">To: Peter (BOUGHTONP) <span><span class="image post_read" title="Read: 26 May 2020 10:54"></span></span> <span class="message_count">3 of 10</span><div class="clearer"></div> </div> </div> <div class="message_links"> <a href="lmessages.php?webtag=DEFAULT&msg=42633.3">42633.3</a> In reply to <a href="lmessages.php?webtag=DEFAULT&msg=42633.1#a42633_2" target="_self">42633.2</a></div> <div class="message_body"> I got that massively wrong up there - have edited.</div> <div class="message_footer"> <div class="message_footer_links"><a href="lpost.php?webtag=DEFAULT&reply_to=42633.3&return_msg=42633.1" class="reply"><span class="image post"></span>Reply</a></div> <div class="message_vote_form" data-msg="42633.3"> <span class="rating">0/0</span> <span class="image vote vote_down vote_down_off" title="Vote Down"></span> <span class="image vote vote_up vote_up_off" title="Vote Up"></span> </div> </div> </div><a name="a42633_4"></a><div class="message" id="message_42633_4"> <div class="message_header"> <div class="message_from"> From: Peter (BOUGHTONP)<span class="message_time">26 May 2020 11:00</span> <div class="clearer"></div> </div><div class="message_to">To: ANT_THOMAS <span><span class="image post_read" title="Read: 26 May 2020 11:01"></span></span> <span class="message_count">4 of 10</span><div class="clearer"></div> </div> </div> <div class="message_links"> <a href="lmessages.php?webtag=DEFAULT&msg=42633.4">42633.4</a> In reply to <a href="lmessages.php?webtag=DEFAULT&msg=42633.1#a42633_3" target="_self">42633.3</a></div> <div class="message_body"> So the other numbers are definitely all correct? <p>How does the data actually come in - presumably it's either binary or hex encoded rather than decimals? </p><p>Shouldn't the sensor provide documentation of the format? (Or does it expect using its own crappy software?)</p></div> <div class="message_footer"> <div class="message_footer_links"><a href="lpost.php?webtag=DEFAULT&reply_to=42633.4&return_msg=42633.1" class="reply"><span class="image post"></span>Reply</a></div> <div class="message_vote_form" data-msg="42633.4"> <span class="rating">0/0</span> <span class="image vote vote_down vote_down_off" title="Vote Down"></span> <span class="image vote vote_up vote_up_off" title="Vote Up"></span> </div> </div> </div><a name="a42633_5"></a><div class="message" id="message_42633_5"> <div class="message_header"> <div class="message_from"> From: ANT_THOMAS<span class="message_time">26 May 2020 11:01</span> <div class="clearer"></div> </div><div class="message_to">To: Peter (BOUGHTONP) <span><span class="image post_read" title="Read: 26 May 2020 11:01"></span></span> <span class="message_count">5 of 10</span><div class="clearer"></div> </div> </div> <div class="message_links"> <a href="lmessages.php?webtag=DEFAULT&msg=42633.5">42633.5</a> In reply to <a href="lmessages.php?webtag=DEFAULT&msg=42633.1#a42633_2" target="_self">42633.2</a></div> <div class="message_body"> I have now figured it out, kinda.<br /> So it seems the temps are 3dp and there has been some rounding which put me off the scent a bit.<br /> The encoding is IEEE 754<br /> <br /> And goes as follows<br /> <br /> 0, 0, <strong>108, 65,</strong> 60, 16, 0, 0, 97, 0<br /> <br /> In binary<br /> 65 = 01000001<br /> 108 = 01101100<br /> <br /> Then put that in a suitable sequence for IEEE 754 with 0 padding at the end<br /> 01000001 01101100 00000000 00000000<br /> <br /> That converts to 14.75.<br /> <br /> Just need to do the binary to IEEE 754 floating point number in bash somehow, or at least called from a bash script now I have the binary numbers in bash.<br /> </div> <div class="message_footer"> <div class="message_footer_links"><a href="lpost.php?webtag=DEFAULT&reply_to=42633.5&return_msg=42633.1" class="reply"><span class="image post"></span>Reply</a></div> <div class="message_vote_form" data-msg="42633.5"> <span class="rating">0/0</span> <span class="image vote vote_down vote_down_off" title="Vote Down"></span> <span class="image vote vote_up vote_up_off" title="Vote Up"></span> </div> </div> </div><a name="a42633_6"></a><div class="message" id="message_42633_6"> <div class="message_header"> <div class="message_from"> From: ANT_THOMAS<span class="message_time">26 May 2020 11:06</span> <div class="clearer"></div> </div><div class="message_to">To: ANT_THOMAS <span><span class="image post_read" title="Read: 26 May 2020 11:06"></span></span> <span class="message_count">6 of 10</span><div class="clearer"></div> </div> </div> <div class="message_links"> <a href="lmessages.php?webtag=DEFAULT&msg=42633.6">42633.6</a> In reply to <a href="lmessages.php?webtag=DEFAULT&msg=42633.1#a42633_5" target="_self">42633.5</a></div> <div class="message_body"> Also, the leading zeros in the array may be the padding at the end, as some other examples contain "128" at place 2, so I think I need to include them. But that's easy enough.<br /> <strong>0, 0</strong>, 108, 65</div> <div class="message_footer"> <div class="message_footer_links"><a href="lpost.php?webtag=DEFAULT&reply_to=42633.6&return_msg=42633.1" class="reply"><span class="image post"></span>Reply</a></div> <div class="message_vote_form" data-msg="42633.6"> <span class="rating">0/0</span> <span class="image vote vote_down vote_down_off" title="Vote Down"></span> <span class="image vote vote_up vote_up_off" title="Vote Up"></span> </div> </div> </div><a name="a42633_7"></a><div class="message" id="message_42633_7"> <div class="message_header"> <div class="message_from"> From: ANT_THOMAS<span class="message_time">26 May 2020 11:08</span> <div class="clearer"></div> </div><div class="message_to">To: Peter (BOUGHTONP) <span><span class="image post_read" title="Read: 26 May 2020 11:10"></span></span> <span class="message_count">7 of 10</span><div class="clearer"></div> </div> </div> <div class="message_links"> <a href="lmessages.php?webtag=DEFAULT&msg=42633.7">42633.7</a> In reply to <a href="lmessages.php?webtag=DEFAULT&msg=42633.1#a42633_4" target="_self">42633.4</a></div> <div class="message_body"> Numbers are correct, as I've now manually successfully decoded it.<br /> In terms of documentation, I've made and coded these sensors myself, I just didn't entirely understand how the data was encoded with the library (RadioHead ASK).<br /> <br /> Now just need to figure out a command line binary to IEEE 754 floating point number conversion.</div> <div class="message_footer"> <div class="message_footer_links"><a href="lpost.php?webtag=DEFAULT&reply_to=42633.7&return_msg=42633.1" class="reply"><span class="image post"></span>Reply</a></div> <div class="message_vote_form" data-msg="42633.7"> <span class="rating">0/0</span> <span class="image vote vote_down vote_down_off" title="Vote Down"></span> <span class="image vote vote_up vote_up_off" title="Vote Up"></span> </div> </div> </div><a name="a42633_8"></a><div class="message" id="message_42633_8"> <div class="message_header"> <div class="message_from"> From: Peter (BOUGHTONP)<span class="message_time">26 May 2020 11:21</span> <div class="clearer"></div> </div><div class="message_to">To: ANT_THOMAS <span><span class="image post_read" title="Read: 26 May 2020 11:25"></span></span> <span class="message_count">8 of 10</span><div class="clearer"></div> </div> </div> <div class="message_links"> <a href="lmessages.php?webtag=DEFAULT&msg=42633.8">42633.8</a> In reply to <a href="lmessages.php?webtag=DEFAULT&msg=42633.1#a42633_7" target="_self">42633.7</a></div> <div class="message_body"> Bash doesn't do floating point, but I still expected it to be a simple case of calling <b>bc</b> or something, but nothing useful comes up from relevant searches. <p>Guess you'll have to convert your manual steps to Perl or Python?</p></div> <div class="message_footer"> <div class="message_footer_links"><a href="lpost.php?webtag=DEFAULT&reply_to=42633.8&return_msg=42633.1" class="reply"><span class="image post"></span>Reply</a></div> <div class="message_vote_form" data-msg="42633.8"> <span class="rating">0/0</span> <span class="image vote vote_down vote_down_off" title="Vote Down"></span> <span class="image vote vote_up vote_up_off" title="Vote Up"></span> </div> </div> </div><a name="a42633_9"></a><div class="message" id="message_42633_9"> <div class="message_header"> <div class="message_from"> From: ANT_THOMAS<span class="message_time">26 May 2020 11:26</span> <div class="clearer"></div> </div><div class="message_to">To: Peter (BOUGHTONP) <span><span class="image post_read" title="Read: 26 May 2020 13:16"></span></span> <span class="message_count">9 of 10</span><div class="clearer"></div> </div> </div> <div class="message_links"> <a href="lmessages.php?webtag=DEFAULT&msg=42633.9">42633.9</a> In reply to <a href="lmessages.php?webtag=DEFAULT&msg=42633.1#a42633_8" target="_self">42633.8</a></div> <div class="message_body"> Yeah, seen similar. Was wanting to use bc. Now looking at some other simple programs, C++, Perl or Python should handle it, then feed it back in.</div> <div class="message_footer"> <div class="message_footer_links"><a href="lpost.php?webtag=DEFAULT&reply_to=42633.9&return_msg=42633.1" class="reply"><span class="image post"></span>Reply</a></div> <div class="message_vote_form" data-msg="42633.9"> <span class="rating">0/0</span> <span class="image vote vote_down vote_down_off" title="Vote Down"></span> <span class="image vote vote_up vote_up_off" title="Vote Up"></span> </div> </div> </div><a name="a42633_10"></a><div class="message" id="message_42633_10"> <div class="message_header"> <div class="message_from"> From: ANT_THOMAS<span class="message_time">26 May 2020 12:36</span> <div class="clearer"></div> </div><div class="message_to">To: ALL<span class="message_count">10 of 10</span><div class="clearer"></div> </div> </div> <div class="message_links"> <a href="lmessages.php?webtag=DEFAULT&msg=42633.10">42633.10</a></div> <div class="message_body"> Done, decoded using some simple python.</div> <div class="message_footer"> <div class="message_footer_links"><a href="lpost.php?webtag=DEFAULT&reply_to=42633.10&return_msg=42633.1" class="reply"><span class="image post"></span>Reply</a></div> <div class="message_vote_form" data-msg="42633.10"> <span class="rating">0/0</span> <span class="image vote vote_down vote_down_off" title="Vote Down"></span> <span class="image vote vote_up vote_up_off" title="Vote Up"></span> </div> </div> </div></div> </div> </body>