| 0,0 → 1,595 |
|---|
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| <P align=center><B><FONT size=5>SRF08 Ultra sonic range finder </FONT><FONT |
| size=3><BR>Technical Specification</FONT></B></P> |
| <P align=left>Communication with the SRF08 ultrasonic rangefinder is via the I2C |
| bus. This is available on popular controllers such as the OOPic and Stamp BS2p, |
| as well as a wide variety of micro-controllers. To the programmer the SRF08 |
| behaves in the same way as the ubiquitous 24xx series eeprom's, except that the |
| I2C address is different. The default shipped address of the SRF08 is 0xE0. It |
| can be changed by the user to any of 16 addresses E0, E2, E4, E6, E8, EA, EC, |
| EE, F0, F2, F4, F6, F8, FA, FC or FE, therefore up to 16 sonar's can be used. In |
| addition to the above addresses, all sonar's on the I2C bus will respond to |
| address 0 - the General Broadcast address. This means that writing a ranging |
| command to I2C address 0 (0x00) will start all sonar's ranging at the same time. |
| This should be useful in ANN Mode (See below). The results must be read |
| individually from each sonar's real address. We have <A |
| href="http://www.robot-electronics.co.uk/htm/examples.shtml">examples</A> of |
| using the SRF08 module with a wide range of popular controllers.</P> |
| <P align=left><B>Connections<BR></B>The "Do Not Connect" pin should be left |
| unconnected. It is actually the CPU MCLR line and is used once only in our |
| workshop to program the PIC16F872 on-board after assembly, and has an internal |
| pull-up resistor. The SCL and SDA lines should each have a pull-up resistor to |
| +5v somewhere on the I2C bus. You only need one pair of resistors, not a pair |
| for every module. They are normally located with the bus master rather than the |
| slaves. The SRF08 is always a slave - never a bus master. If you need them, I |
| recommend 1.8k resistors. Some modules such as the OOPic already have pull-up |
| resistors and you do not need to add any more. </P> |
| <P align=center><IMG height=232 |
| src="SRF08 Ultra sonic range finder_files/srf08con.jpg" width=302 border=0></P> |
| <P align=left><B>Registers</B><BR> The SRF08 appears as a set of 36 |
| registers.</P> |
| <DIV align=center> |
| <CENTER> |
| <TABLE cellSpacing=0 cellPadding=0 width="53%" bgColor=#ffffcc border=1> |
| <TBODY> |
| <TR> |
| <TD width="24%"> |
| <P align=center>Location</P></TD> |
| <TD width="32%"> |
| <P align=center>Read</P></TD> |
| <TD width="44%"> |
| <P align=center>Write</P></TD></TR> |
| <TR> |
| <TD width="24%"> |
| <P align=center>0</P></TD> |
| <TD width="32%"> |
| <P align=center>Software Revision</P></TD> |
| <TD width="44%"> |
| <P align=center>Command Register</P></TD></TR> |
| <TR> |
| <TD width="24%"> |
| <P align=center>1</P></TD> |
| <TD width="32%"> |
| <P align=center>Light Sensor</P></TD> |
| <TD width="44%"> |
| <P align=center>Max Gain Register (default 31) </P></TD></TR> |
| <TR> |
| <TD width="24%"> |
| <P align=center>2</P></TD> |
| <TD width="32%"> |
| <P align=center>1st Echo High Byte</P></TD> |
| <TD width="44%"> |
| <P align=center>Range Register (default 255)</P></TD></TR> |
| <TR> |
| <TD width="24%"> |
| <P align=center>3</P></TD> |
| <TD width="32%"> |
| <P align=center>1st Echo Low Byte</P></TD> |
| <TD width="44%"> |
| <P align=center>N/A</P></TD></TR> |
| <TR> |
| <TD width="24%"> |
| <P align=center>~~~~</P></TD> |
| <TD width="32%"> |
| <P align=center>~~~~</P></TD> |
| <TD width="44%"> |
| <P align=center>~~~~</P></TD></TR> |
| <TR> |
| <TD width="24%"> |
| <P align=center>34</P></TD> |
| <TD width="32%"> |
| <P align=center>17th Echo High Byte</P></TD> |
| <TD width="44%"> |
| <P align=center>N/A</P></TD></TR> |
| <TR> |
| <TD width="24%"> |
| <P align=center>35</P></TD> |
| <TD width="32%"> |
| <P align=center>17th Echo Low Byte</P></TD> |
| <TD width="44%"> |
| <P align=center>N/A</P></TD></TR></TBODY></TABLE></CENTER></DIV> |
| <P align=left>Only locations 0, 1 and 2 can be written to. Location 0 is the |
| command register and is used to start a ranging session. It cannot be read. |
| Reading from location 0 returns the SRF08 software revision. By default, |
| the ranging lasts for 65mS, but can be changed by writing to the range register |
| at location 2. If you do so, then you will likely need to change the analogue |
| gain by writing to location 1. See the <B>Changing Range</B> and <B>Analogue |
| Gain</B> sections below.</P> |
| <P align=left>Location 1 is the onboard light sensor. This data is updated every |
| time a new ranging command has completed and can be read when range data is |
| read. The next two locations, 2 and 3, are the 16bit unsigned result from the |
| latest ranging - high byte first. The meaning of this value depends on the |
| command used, and is either the range in inches, or the range in cm or the |
| flight time in uS. A value of zero indicates that no objects were detected. |
| There are up to a further 16 results indicating echo's from more distant |
| objects. </P> |
| <P align=left><B>Commands</B><BR>The are three commands to initiate a ranging |
| (80 to 82), to return the result in inches, centimeters or microseconds. There |
| is also an ANN mode (Artificial Neural Network) mode which is described later |
| and a set of commands to change the I2C address.</P> |
| <DIV align=center> |
| <CENTER> |
| <TABLE cellSpacing=0 cellPadding=0 width="77%" bgColor=#ffffcc border=1> |
| <TBODY> |
| <TR> |
| <TD align=middle width="34%" colSpan=2>Command</TD> |
| <TD align=middle width="94%" rowSpan=2>Action</TD></TR> |
| <TR> |
| <TD align=middle width="16%">Decimal</TD> |
| <TD align=middle width="18%">Hex</TD></TR> |
| <TR> |
| <TD align=middle width="16%">80</TD> |
| <TD align=middle width="18%">0x50</TD> |
| <TD align=left width="94%">Ranging Mode - Result in inches</TD></TR> |
| <TR> |
| <TD align=middle width="16%">81</TD> |
| <TD align=middle width="18%">0x51</TD> |
| <TD align=left width="94%">Ranging Mode - Result in centimeters</TD></TR> |
| <TR> |
| <TD align=middle width="16%">82</TD> |
| <TD align=middle width="18%">0x52</TD> |
| <TD align=left width="94%">Ranging Mode - Result in micro-seconds</TD></TR> |
| <TR> |
| <TD align=middle width="16%"> </TD> |
| <TD align=middle width="18%"> </TD> |
| <TD align=left width="94%"> </TD></TR> |
| <TR> |
| <TD align=middle width="16%">83</TD> |
| <TD align=middle width="18%">0x53</TD> |
| <TD align=left width="94%">ANN Mode - Result in inches</TD></TR> |
| <TR> |
| <TD align=middle width="16%">84</TD> |
| <TD align=middle width="18%">0x54</TD> |
| <TD align=left width="94%">ANN Mode - Result in centimeters</TD></TR> |
| <TR> |
| <TD align=middle width="16%">85</TD> |
| <TD align=middle width="18%">0x55</TD> |
| <TD align=left width="94%">ANN Mode - Result in micro-seconds</TD></TR> |
| <TR> |
| <TD align=middle width="16%"> </TD> |
| <TD align=middle width="18%"> </TD> |
| <TD align=left width="94%"> </TD></TR> |
| <TR> |
| <TD align=middle width="16%">160</TD> |
| <TD align=middle width="18%">0xA0</TD> |
| <TD align=left width="94%">1st in sequence to change I2C address</TD></TR> |
| <TR> |
| <TD align=middle width="16%">165</TD> |
| <TD align=middle width="18%">0xA5</TD> |
| <TD align=left width="94%">3rd in sequence to change I2C address</TD></TR> |
| <TR> |
| <TD align=middle width="16%">170</TD> |
| <TD align=middle width="18%">0xAA</TD> |
| <TD align=left width="94%">2nd in sequence to change I2C |
| address</TD></TR></TBODY></TABLE></CENTER></DIV> |
| <P align=left><B>Ranging Mode</B><BR>To initiate a ranging, write one of the |
| above commands to the command register and wait the required amount of time for |
| completion and read as many results as you wish. The echo buffer is cleared at |
| the start of each ranging. The first echo range is placed in locations 2,3. the |
| second in 4,5, etc. If a location (high and low bytes) is 0, then there will be |
| no further reading in the rest of the registers. The default and recommended |
| time for completion of ranging is 65mS, however you can shorten this by writing |
| to the range register before issuing a ranging command. Light sensor data at |
| location 1 will also have been updated after a ranging command. </P> |
| <P align=left><B>ANN Mode<BR></B>ANN mode (Artificial Neural Network) is |
| designed to provide the multi echo data in a way that is easier to input to a |
| neural network, at least I hope it is - I've not actually done it yet. ANN mode |
| provides a 32 byte buffer (locations 4 to 35 inclusive) where each byte |
| represents the 65536uS maximum flight time divided into 32 chunks of 2048uS each |
| - equivalent to about 352mm of range. If an echo is received within a bytes time |
| slot then it will be set to no-zero, otherwise it will be zero. So if an echo is |
| received from within the first 352mm, location 4 will be non-zero. If an object |
| is detected 3m away the location 12 will be non-zero (3000/352 = 8) (8+4=12). |
| Arranging the data like this should be better for a neural net than the other |
| formats. The input to your network should be 0 if the byte is zero and 1 if its |
| non-zero. I have a SOFM (Self Organizing Feature Map) in mind for the neural |
| net, but will hopefully be useful for any type. </P> |
| <DIV align=center> |
| <CENTER> |
| <TABLE cellSpacing=0 cellPadding=0 width="71%" bgColor=#ffffcc border=1> |
| <TBODY> |
| <TR> |
| <TD align=middle width="20%">Location 4</TD> |
| <TD align=middle width="20%">Location 5</TD> |
| <TD align=middle width="20%">Location 6</TD> |
| <TD align=middle width="20%">Location 7</TD> |
| <TD align=middle width="20%">Locations 8 - 35</TD></TR> |
| <TR> |
| <TD align=middle width="20%">0 - 352mm</TD> |
| <TD align=middle width="20%">353 - 705mm</TD> |
| <TD align=middle width="20%">706 - 1057mm</TD> |
| <TD align=middle width="20%">1058 - 1410mm</TD> |
| <TD align=middle width="20%">and so on</TD></TR></TBODY></TABLE></CENTER></DIV> |
| <P align=left>Locations 2,3 contain the range of the nearest object converted to |
| inches, cm or uS and is the same as for Ranging Mode.</P> |
| <P align=left><B>Checking for Completion of Ranging</B><BR>You do not have to |
| use a timer on your own controller to wait for ranging to finish. You can take |
| advantage of the fact that the SRF08 will not respond to any I2C activity whilst |
| ranging. Therefore, if you try to read from the SRF08 (we use the software |
| revision number a location 0) then you will get 255 (0xFF) whilst ranging. This |
| is because the I2C data line (SDA) is pulled high if nothing is driving it. As |
| soon as the ranging is complete the SRF08 will again respond to the I2C bus, so |
| just keep reading the register until its not 255 (0xFF) anymore. You can then |
| read the sonar data. Your controller can take advantage of this to perform other |
| tasks while the SRF08 is ranging. </P> |
| <P align=left><B>Changing the Range</B><BR>The maximum range of the SRF08 is set |
| by an internal timer. By default, this is 65mS or the equivalent of 11 metres of |
| range. This is much further than the 6 metres the SRF08 is actually |
| capable of. It is possible to reduce the time the SRF08 listens for an echo, and |
| hence the range, by writing to the range register at location 2. The range can |
| be set in steps of about 43mm (0.043m or 1.68 inches) up to 11 |
| metres. <BR>The range is ((Range Register x 43mm) + 43mm) so setting the |
| Range Register to 0 (0x00) gives a maximum range of 43mm. Setting the Range |
| Register to 1 (0x01) gives a maximum range of 86mm. More usefully, 24 (0x18) |
| gives a range of 1 metre and 140 (0x8C) is 6 metres. Setting 255 (0xFF) gives |
| the original 11 metres (255 x 43 + 43 is 11008mm). There are two reasons you may |
| wish to reduce the range.<BR>1. To get at the range information quicker<BR>2. To |
| be able to fire the SRF08 at a faster rate.<BR>If you only wish to get at the |
| range information a bit sooner and will continue to fire the SRF08 at 65ms of |
| slower, then all will be well. However if you wish to fire the SRF08 at a faster |
| rate than 65mS, you will definitely need to reduce the gain - see next |
| section.<BR>The range is set to maximum every time the SRF08 is powered-up. If |
| you need a different range, change it once as part of your system initialization |
| code.<BR></P> |
| <P align=left><B>Analogue Gain</B><BR>The analogue gain register sets the |
| <I>Maximum</I> gain of the analogue stages. To set the maximum gain, just write |
| one of these values to the gain register at location 1. During a ranging, the |
| analogue gain starts off at its minimum value of 94. This is increased at |
| approx. 70uS intervals up to the maximum gain setting, set by register |
| 1. Maximum possible gain is reached after about 390mm of range. The purpose |
| of providing a limit to the maximum gain is to allow you to fire the sonar more |
| rapidly than 65mS. Since the ranging can be very short, a new ranging can be |
| initiated as soon as the previous range data has been read. A potential hazard |
| with this is that the second ranging may pick up a distant echo returning from |
| the previous "ping", give a false result of a close by object when there is |
| none. To reduce this possibility, the maximum gain can be reduced to limit the |
| modules sensitivity to the weaker distant echo, whilst still able to detect |
| close by objects. The maximum gain setting is stored only in the CPU's RAM and |
| is initialized to maximum on power-up, so if you only want do a ranging every |
| 65mS, or longer, you can ignore the Range and Gain Registers.<BR><I><B><FONT |
| color=#ff00ff>Note</FONT></B></I> - Effective in Ranging Mode only, in ANN mode, |
| gain is controlled automatically. </P> |
| <DIV align=center> |
| <CENTER> |
| <TABLE height=714 cellSpacing=0 cellPadding=0 width=428 bgColor=#ffffcc |
| border=1> |
| <TBODY> |
| <TR> |
| <TD align=middle width=157 colSpan=2 height=19>Gain Register</TD> |
| <TD align=middle width=265 height=40 rowSpan=2>Maximum Analogue Gain</TD></TR> |
| <TR> |
| <TD align=middle width=77 height=19>Decimal</TD> |
| <TD align=middle width=80 height=19>Hex</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>0</TD> |
| <TD align=middle width=81 height=19>0x00</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to 94</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>1</TD> |
| <TD align=middle width=81 height=19>0x01</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to 97</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>2</TD> |
| <TD align=middle width=81 height=19>0x02</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 100</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>3</TD> |
| <TD align=middle width=81 height=19>0x03</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 103</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>4</TD> |
| <TD align=middle width=81 height=19>0x04</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 107</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>5</TD> |
| <TD align=middle width=81 height=19>0x05</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 110</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>6</TD> |
| <TD align=middle width=81 height=19>0x06</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 114</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>7</TD> |
| <TD align=middle width=81 height=19>0x07</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 118</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>8</TD> |
| <TD align=middle width=81 height=19>0x08</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 123</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>9</TD> |
| <TD align=middle width=81 height=19>0x09</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 128</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>10</TD> |
| <TD align=middle width=81 height=19>0x0A</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 133</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>11</TD> |
| <TD align=middle width=81 height=19>0x0B</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 139</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>12</TD> |
| <TD align=middle width=81 height=19>0x0C</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 145</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>13</TD> |
| <TD align=middle width=81 height=19>0x0D</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 152</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>14</TD> |
| <TD align=middle width=81 height=19>0x0E</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 159</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>15</TD> |
| <TD align=middle width=81 height=19>0x0F</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 168</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>16</TD> |
| <TD align=middle width=81 height=19>0x10</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 177</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>17</TD> |
| <TD align=middle width=81 height=19>0x11</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 187</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>18</TD> |
| <TD align=middle width=81 height=19>0x12</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 199</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>19</TD> |
| <TD align=middle width=81 height=19>0x13</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 212</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>20</TD> |
| <TD align=middle width=81 height=19>0x14</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 227</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>21</TD> |
| <TD align=middle width=81 height=19>0x15</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 245</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>22</TD> |
| <TD align=middle width=81 height=19>0x16</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 265</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>23</TD> |
| <TD align=middle width=81 height=19>0x17</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 288</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>24</TD> |
| <TD align=middle width=81 height=19>0x18</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 317</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>25</TD> |
| <TD align=middle width=81 height=19>0x18</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 352</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>26</TD> |
| <TD align=middle width=81 height=19>0x20</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 395</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>27</TD> |
| <TD align=middle width=81 height=19>0x21</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 450</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>28</TD> |
| <TD align=middle width=81 height=19>0x22</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 524</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>29</TD> |
| <TD align=middle width=81 height=19>0x23</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 626</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>30</TD> |
| <TD align=middle width=81 height=19>0x24</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 777</TD></TR> |
| <TR> |
| <TD align=middle width=74 height=19>31</TD> |
| <TD align=middle width=81 height=19>0x25</TD> |
| <TD align=middle width=265 height=19>Set Maximum Analogue Gain to |
| 1025</TD></TR></TBODY></TABLE></CENTER></DIV> |
| <P align=left>Note that the relationship between the Gain Register setting and |
| the actual gain is not a linear one. Also there is no magic formula to say "use |
| this gain setting with that range setting". It depends on the size, shape and |
| material of the object and what else is around in the room. Try playing with |
| different settings until you get the result you want. If you appear to get false |
| readings, it may be echo's from previous "pings", try going back to firing the |
| SRF08 every 65mS or longer (slower). <BR>If you are in any doubt about the |
| Range and Gain Registers, remember they are automatically set by the SRF08 to |
| their default values when it is powered-up. You can ignore and forget about them |
| and the SRF08 will work fine, detecting objects up to 6 metres away every 65mS |
| or slower.</P> |
| <P align=left><B>Light Sensor</B><BR>The SRF08 has a light sensor on-board. A |
| reading of the light intensity is made by the SRF08 each time a ranging takes |
| place in either Ranging or ANN Modes ( The A/D conversion is actually done just |
| before the "ping" whilst the +/- 10v generator is stabilizing). The reading |
| increases as the brightness increases, so you will get a maximum value in bright |
| light and minimum value in darkness. It should get close to 2-3 in complete |
| darkness and up to about 248 (0xF8) in bright light. The light intensity can be |
| read from the Light Sensor Register at location 1 at the same time that |
| you are reading the range data.</P> |
| <P align=left><B>LED</B><BR>The red LED is used to flash out a code for the I2C |
| address on power-up (see below). It also gives a brief flash during the "ping" |
| whilst ranging.</P> |
| <P align=left><B>Changing the I2C Bus Address</B><BR>To change the I2C address |
| of the SRF08 you must have only one sonar on the bus. Write the 3 sequence |
| commands in the correct order followed by the address. Example; to change the |
| address of a sonar currently at 0xE0 (the default shipped address) to 0xF2, |
| write the following to address 0xE0; (0xA0, 0xAA, 0xA5, 0xF2 ). These commands |
| must be sent in the correct sequence to change the I2C address, additionally, No |
| other command may be issued in the middle of the sequence. The sequence must be |
| sent to the command register at location 0, which means 4 separate write |
| transactions on the I2C bus. When done, you should label the sonar with its |
| address, however if you do forget, just power it up without sending any |
| commands. The SRF08 will flash its address out on the LED. One long flash |
| followed by a number of shorter flashes indicating its address. The flashing is |
| terminated immediately on sending a command the SRF08.</P> |
| <DIV align=center> |
| <CENTER> |
| <TABLE cellSpacing=0 cellPadding=0 width="45%" bgColor=#ffffcc border=1> |
| <TBODY> |
| <TR> |
| <TD align=middle width="45%" colSpan=2>Address</TD> |
| <TD align=middle width="25%" rowSpan=2>Long Flash</TD> |
| <TD align=middle width="30%" rowSpan=2>Short flashes</TD></TR> |
| <TR> |
| <TD align=middle width="23%">Decimal</TD> |
| <TD align=middle width="22%">Hex</TD></TR> |
| <TR> |
| <TD align=middle width="23%">224</TD> |
| <TD align=middle width="22%">E0</TD> |
| <TD align=middle width="25%">1</TD> |
| <TD align=middle width="30%">0</TD></TR> |
| <TR> |
| <TD align=middle width="23%">226</TD> |
| <TD align=middle width="22%">E2</TD> |
| <TD align=middle width="25%">1</TD> |
| <TD align=middle width="30%">1</TD></TR> |
| <TR> |
| <TD align=middle width="23%">228</TD> |
| <TD align=middle width="22%">E4</TD> |
| <TD align=middle width="25%">1</TD> |
| <TD align=middle width="30%">2</TD></TR> |
| <TR> |
| <TD align=middle width="23%">230</TD> |
| <TD align=middle width="22%">E6</TD> |
| <TD align=middle width="25%">1</TD> |
| <TD align=middle width="30%">3</TD></TR> |
| <TR> |
| <TD align=middle width="23%">232</TD> |
| <TD align=middle width="22%">E8</TD> |
| <TD align=middle width="25%">1</TD> |
| <TD align=middle width="30%">4</TD></TR> |
| <TR> |
| <TD align=middle width="23%">234</TD> |
| <TD align=middle width="22%">EA</TD> |
| <TD align=middle width="25%">1</TD> |
| <TD align=middle width="30%">5</TD></TR> |
| <TR> |
| <TD align=middle width="23%">236</TD> |
| <TD align=middle width="22%">EC</TD> |
| <TD align=middle width="25%">1</TD> |
| <TD align=middle width="30%">6</TD></TR> |
| <TR> |
| <TD align=middle width="23%">238</TD> |
| <TD align=middle width="22%">EE</TD> |
| <TD align=middle width="25%">1</TD> |
| <TD align=middle width="30%">7</TD></TR> |
| <TR> |
| <TD align=middle width="23%">240</TD> |
| <TD align=middle width="22%">F0</TD> |
| <TD align=middle width="25%">1</TD> |
| <TD align=middle width="30%">8</TD></TR> |
| <TR> |
| <TD align=middle width="23%">242</TD> |
| <TD align=middle width="22%">F2</TD> |
| <TD align=middle width="25%">1</TD> |
| <TD align=middle width="30%">9</TD></TR> |
| <TR> |
| <TD align=middle width="23%">244</TD> |
| <TD align=middle width="22%">F4</TD> |
| <TD align=middle width="25%">1</TD> |
| <TD align=middle width="30%">10</TD></TR> |
| <TR> |
| <TD align=middle width="23%">246</TD> |
| <TD align=middle width="22%">F6</TD> |
| <TD align=middle width="25%">1</TD> |
| <TD align=middle width="30%">11</TD></TR> |
| <TR> |
| <TD align=middle width="23%">248</TD> |
| <TD align=middle width="22%">F8</TD> |
| <TD align=middle width="25%">1</TD> |
| <TD align=middle width="30%">12</TD></TR> |
| <TR> |
| <TD align=middle width="23%">250</TD> |
| <TD align=middle width="22%">FA</TD> |
| <TD align=middle width="25%">1</TD> |
| <TD align=middle width="30%">13</TD></TR> |
| <TR> |
| <TD align=middle width="23%">252</TD> |
| <TD align=middle width="22%">FC</TD> |
| <TD align=middle width="25%">1</TD> |
| <TD align=middle width="30%">14</TD></TR> |
| <TR> |
| <TD align=middle width="23%">254</TD> |
| <TD align=middle width="22%">FE</TD> |
| <TD align=middle width="25%">1</TD> |
| <TD align=middle width="30%">15</TD></TR></TBODY></TABLE></CENTER></DIV> |
| <P align=left>Take care not to set more than one sonar to the same address, |
| there will be a bus collision and very unpredictable results.</P> |
| <P align=left><B>Current Consumption</B><BR>Average current consumption measured |
| on our prototype is around 12mA during ranging, and 3mA standby. The module will |
| automatically go to standby mode after a ranging, whilst waiting for a new |
| command on the I2C bus. The actual measured current profile is as follows; </P> |
| <DIV align=center> |
| <CENTER> |
| <TABLE cellSpacing=0 width=400 bgColor=#ffffcc border=1> |
| <TBODY> |
| <TR> |
| <TD align=middle width=253>Operation</TD> |
| <TD align=middle width=62>Current</TD> |
| <TD align=middle width=65>Duration</TD></TR> |
| <TR> |
| <TD align=middle width=253>Ranging command received - Power on</TD> |
| <TD align=middle width=62>275mA</TD> |
| <TD align=middle width=65>3uS</TD></TR> |
| <TR> |
| <TD align=middle width=253>+/- 10v generator Stabilization</TD> |
| <TD align=middle width=62> |
| <P align=center>25mA</P></TD> |
| <TD align=middle width=65>600uS</TD></TR> |
| <TR> |
| <TD align=middle width=253>8 cycles of 40kHz "ping"</TD> |
| <TD align=middle width=62>40mA</TD> |
| <TD align=middle width=65>200uS</TD></TR> |
| <TR> |
| <TD align=middle width=253>Ranging</TD> |
| <TD align=middle width=62>11mA</TD> |
| <TD align=middle width=65>65mS max</TD></TR> |
| <TR> |
| <TD align=middle width=253>Standby</TD> |
| <TD align=middle width=62>3mA</TD> |
| <TD align=middle width=65>indefinite</TD></TR></TBODY></TABLE></CENTER></DIV> |
| <P align=left>The above values are for guidance only, they are not tested on |
| production units. </P> |
| <P align=left> You can have a look at the <A |
| href="http://www.robot-electronics.co.uk/images/srf08schematic.gif">schematic</A> |
| and <A href="http://www.robot-electronics.co.uk/files/srf08.c">software</A> </P> |
| <P align=left>Your feedback/comments/criticisms and wish lists are very welcome, |
| as always.<BR>Regards, Gerry. |
| <BR>gerry@robot-electronics.co.uk</P></BODY></HTML> |