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<!doctype html public "-//w3c//dtd html 4.0 transitional//en"><html><head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <meta name="GENERATOR" content="Mozilla/4.78 [en] (X11; U; Linux 2.4.7-10 i686) [Netscape]"> <title>TinyOS Tutorial Lesson 8: Data logging application</title></head><body bgcolor="#F8F8FF" link="#005BB7" vlink="#005BB7"> <table BORDER=0 CELLSPACING=2 CELLPADDING=3 WIDTH="100%" hspace="4" ><tr BGCOLOR="#E0E0FF"><td WIDTH="100%"><b><font face="tahoma,arial,helvetica"><font size=-1>Lesson8: Data logging application</font></font></b><p><font face="tahoma,arial,helvetica">Last updated 9 September 2003</font></td></tr></table><p>This lesson will discuss a fairly complete application for remote datalogging and collection, called <tt>SenseLightToLog</tt>. This is an extensionto <tt>SimpleCmd</tt> that accepts two new commands: one that causes themote to collect sensor readings and write them to the EEPROM, and anotherthat causes the mote to transmit sensor readings from the EEPROM over theradio.<table BORDER=0 CELLSPACING=2 CELLPADDING=3 WIDTH="100%" hspace="4" ><tr BGCOLOR="#E0E0FF"><td WIDTH="100%"><b><nobr><font face="arial,helvetica">The SenseLightToLogApplication</font></nobr></b></td></tr></table><p>The high-level functionality of <tt>SenseLightToLog</tt> can be bestunderstood by looking at the <tt><a href="../../apps/SenseLightToLog/SimpleCmdM.nc">apps/SenseLightToLog/SimpleCmdM.nc</a></tt>component. This is an extended version of the original <tt>SimpleCmd</tt>component from the previous lesson. The <tt>cmdInterpret()</tt> task nowrecognizes two additional commands:<ul><li><tt>START_SENSING</tt>: This command invokes the<tt>Sensing</tt> interfaceto collect a specified number of samples at a specified sampling rate,and to store these samples in mote's EEPROM. The <tt>LoggerWrite</tt> interfaceis used to write the data to the EEPROM.</li><li><tt>READ_LOG</tt>: This command will retrieve a line of data from the EEPROMand broadcast it in a radio packet.</li></ul><table BORDER=0 CELLSPACING=2 CELLPADDING=3 WIDTH="100%" hspace="4" ><tr BGCOLOR="#E0E0FF"><td WIDTH="100%"><b><nobr><font face="arial,helvetica">The Sensing interface</font></nobr></b></td></tr></table><p>We have abstracted the concept of taking a number of sensor readingsbehind the <tt>Sensing</tt> interface, which is implemented by the<tt>SenseLightToLog</tt>component. This interface provides the <tt>start()</tt> command to initiatea series of sensor readings, and signals the <tt>done()</tt> event whensensing has completed.<center><table BORDER=0 CELLSPACING=2 CELLPADDING=3 WIDTH="80%" hspace="4" ><tr BGCOLOR="#E0E0E0"><td WIDTH="100%"><b>SenseLightToLogM.nc</b><pre> command result_t Sensing.start(int samples, int interval_ms) { nsamples = samples; call Timer.start(TIMER_REPEAT, interval_ms); return SUCCESS; } event result_t Timer.fired() { nsamples--; if (nsamples== 0) { call Timer.stop(); signal Sensing.done(); } call Leds.redToggle(); call ADC.getData(); return SUCCESS; } async event result_t ADC.dataReady(uint16_t this_data){ atomic { int p = head; bufferPtr[currentBuffer][p] = this_data; head = (p+1); if (head == maxdata) head = 0; // Wrap around circular buffer if (head == 0) { post writeTask(); } } return SUCCESS; } task void writeTask() { char* ptr; atomic { ptr = (char*)bufferPtr[currentBuffer]; currentBuffer ^= 0x01; // Toggle between two buffers } call LoggerWrite.append(ptr); }</pre></td></tr></table></center><p>When <tt>start()</tt> is invoked, the timer is started to tick at thegiven interval. When the timer event fires, <tt>ADC.getData()</tt> is invokedto get a sensor reading. The <tt>ADC.dataReady()</tt> event causes thesensor reading to be stored in a circular buffer. When the appropriatenumber of samples have been collected the<tt>Sensing.done()</tt> eventis signaled.<p>When <tt>SimpleCmd</tt> receives a <tt>READ_LOG</tt> command, it initiatesan EEPROM read (through <tt>LoggerRead</tt>). When the read has completedit broadcasts the data in a packet. There are 16 bytes in each log entry,which are displayed when you run <tt>BcastInject</tt> tool (as describedbelow).<p>Notice the atomic statements in <tt>ADC.dataReady()</tt> async event.They protect access to the shared variables <tt>head</tt>, <tt>bufferPtr</tt>,and <tt>currentBuffer</tt>. Why do you think the command <tt>LoggerWrite.append()</tt>is called from a task and not from the <tt>ADC.dataReady()</tt> asyncevent ? That is because <tt>LoggerWrite.append()</tt> is <i>not async</i>,so it may not safely preempt other code and should not be called from anasync event.<br> <table BORDER=0 CELLSPACING=2 CELLPADDING=3 WIDTH="100%" hspace="4" ><tr BGCOLOR="#E0E0FF"><td WIDTH="100%"><b><nobr><font face="arial,helvetica">Logger component,interfaces, usage, and limitations</font></nobr></b></td></tr></table><p>The Mica mote has an on-board, 512 kbyte flash EEPROM. The EEPROM servesas a persistent storage device for the mote, and is indispensable for manyapplications involving data collection, such as sensor data and debuggingtraces. The <tt>EEPROMRead</tt> and <tt>EEPROMWrite</tt> interfaces providea clean abstraction to this hardware. The EEPROM may be read and writtenin 16-byte blocks, called <i>lines</i>. Read and write to the EEPROM aresplit-phase operations: one must first initiate a read or write operationand wait for the corresponding <tt>done</tt> event before performing anotheroperation.<p>To simplify access to the EEPROM even further, the <tt>Logger</tt> componentis provided (see <tt><a href="../../tos/system/LoggerM.nc">tos/system/LoggerM.nc</a></tt>).<tt>Logger</tt>maintains an internal pointer to the next EEPROM line to be read or written,treating the EEPROM as a circular buffer that may be accessed sequentially.The logger does not read or write data at the beginning of the EEPROM,which is set aside to store persistent data for the mote. For example,when using network reprogramming of motes, this region stores the <tt>TOS_LOCAL_ADDRESS</tt>of the mote.<p>The <tt>LoggerRead</tt> and <tt>LoggerWrite</tt> interfaces are usedfor reading and writing, respectively. <tt>LoggerRead</tt> provides thecommands:<ul><li><tt>readNext(buffer)</tt> - Read the next line from the log</li><li><tt>read(line, buffer)</tt> - Read an arbitrary line from the log</li><li><tt>resetPointer()</tt> - Set the current line pointer to the beginningof the log</li><li><tt>setPointer(line)</tt> - Set the current line pointer to the given line</li></ul>Likewise, <tt>LoggerWrite</tt> provides the following commands:<ul><li><tt>append(buffer)</tt> - Append data to the log</li><li><tt>write(line, buffer)</tt> - Write data to the log at the given line</li><li><tt>resetPointer()</tt> - Set the current line pointer to the beginningof the log</li><li><tt>setPointer(line)</tt> - Set the current line pointer to the given line</li></ul><table BORDER=0 CELLSPACING=2 CELLPADDING=3 WIDTH="100%" hspace="4" ><tr BGCOLOR="#E0E0FF"><td WIDTH="100%"><b><nobr><font face="arial,helvetica">Logging performance</font></nobr></b></td></tr></table>The <tt>Logger</tt> component does not offer very high performance. Pleasesee the <tt>apps/HighFrequencySampling</tt> application if you areinterested in high-frequency sampling (up to around 5kHz), using the<tt>ByteEEPROM</tt> component. This lesson will eventually be updated toreflect this new component.<table BORDER=0 CELLSPACING=2 CELLPADDING=3 WIDTH="100%" hspace="4" ><tr BGCOLOR="#E0E0FF"><td WIDTH="100%"><b><nobr><font face="arial,helvetica">Data collectionusing SenseLightToLog</font></nobr></b></td></tr></table><p>Program one mote with <tt>SenseLightToLog</tt> and another with TOS<tt>Base</tt>,as before. You may want to attach a sensor board to your mote to get meaningfulphoto readings.<p>The first step is to instruct the mote to take a number of sensor readings.Type<p> <tt>export MOTECOM=serial@COM1:19200</tt><p>Run<pre> java net.tinyos.tools.BcastInject start_sensing <num_samples> <interval></pre>where <tt>num_samples</tt> is the number of samples to take (say, 8 or16), and <tt>interval</tt> is the time in milliseconds between samples(say, 100). For example:<pre> java net.tinyos.tools.BcastInject start_sensing 16 100</pre>You should see the mote's red LED blink while samples are being taken.<p>To get the log data back from the mote, use:<pre> java net.tinyos.tools.BcastInject read_log <mote_address></pre>where <tt>mote_address</tt> is the address of the mote to read log datafrom. For example:<pre> % java net.tinyos.tools.BcastInject read_log 2 Sending payload: 65 6 0 0 0 2 0 0 0 0 0 serial@COM1:19200: resynchronizing Waiting for response to read_log... Received log message: Message <LogMsg> [sourceaddr=0x2] Log values: 48 1 38 1 33 1 32 1 32 1 33 1 34 1 34 1</pre>The program will wait 10 seconds for a response to the <tt>read_log</tt>command; if you don't see a response, try again. If you don't get a reply,then possibly the mote didn't get the command (the green LED will togglefor each command received), or you didn't specify the right<tt>mote_address</tt>.Each subsequent <tt>read_log</tt> command you send will read the next logentry from the mote; if you want to reset the read pointer, just power-cyclethe mote. Remember that the EEPROM data is persistent across power-cycles,but the current read pointer is kept in volatile memory!<p><hr><b><a href="lesson7.html">< Previous Lesson</a></b> |<b><a href="index.html">IndexPage ></a></b> | <b><a href="index.html">Top</a></b></body></html><!-- LocalWords: TinyOS nesC nc async norace BlinkM FooM ncc SingleTimer Leds --><!-- LocalWords: LedsC StdControl tos init TimerC redOn redOff uint redToggle --><!-- LocalWords: metadata html nesdoc gcc exe avr objcopy srec uisp mib dprog --><!-- LocalWords: towards dapa xff ThinkPad dlpt Makelocal micasb Wshadow DDEF --><!-- LocalWords: finline fnesc cfile lm Atmel ATmega nesC's nesc SenseM rdata --><!-- LocalWords: ADCControl SounderControl dataReady getData rcombine someval --><!-- LocalWords: ADControl fooControl barControl MyTimer uniqueCount basicsb --><!-- LocalWords: sensorboard Makerules sensorboards SenseTask taskname INTMSG --><!-- LocalWords: SenseTaskM putdata processData CntToLedsAndRfm RfmToLeds Msg --><!-- LocalWords: CntToRfmAndLeds IntToLeds IntToRfm IntOutput outputComplete --><!-- LocalWords: IntToRfmM GenericComm SendMsg bool struct IntMsg src BCAST --><!-- LocalWords: ADDR sizeof TOSH sendDone GenricComm AMStandard RfmToInt pc --><!-- LocalWords: UARTNoCRCPacket RadioCRCPacket ActiveMessage RfmToIntM xfff --><!-- LocalWords: ReceiveIntMsg ReceiveMsg MsgPtr addr SenseToRfm TOSSIM DBG --><!-- LocalWords: TinyViz ffff crc usr dbg const printf prepended bitmask gdb --><!-- LocalWords: ledsOn gdbinit plugin API TestTinyViz cd tinyviz plugins RFM --><!-- LocalWords: FakeLocation RadioModelPlugin LocationPlugin afterwards disc --><!-- LocalWords: DebugMsgEvent TestTinyVizM AutoRun autorun numsec stopstring --><!-- LocalWords: gridrandom DebugMsgPlugin RadioLinkPlugin radiomodel precmd --><!-- LocalWords: radioscaling nummotes logfile txt logfiles arConfig TOSSIM's --><!-- LocalWords: SimpleCmd TOSBase SerialForwarder BcastInject SimpleCmdM ret --><!-- LocalWords: SimpleCmdMsg Multihop Bcast BcastM ReceiveCmdMsg pmsg msg --><!-- LocalWords: retval greenToggle ProcessCmd SenseLightToLog EEPROM maxdata --><!-- LocalWords: cmdInterpret LoggerWrite SenseLightToLogM nsamples bufferPtr --><!-- LocalWords: currentBuffer writeTask ptr LoggerRead kbyte EEPROMRead num --><!-- LocalWords: EEPROMWrite readNext resetPointer setPointer ByteEEPROM --><!-- LocalWords: HighFrequencySampling MOTECOM LogMsg sourceaddr -->⌨️ 快捷键说明
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