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en:tech:sensorlogger [2020/10/15 17:17] – [Features] bullaren:tech:sensorlogger [2020/10/15 18:30] (current) – external edit 127.0.0.1
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 ==== Protocol ==== ==== Protocol ====
-If you dare to use the IT + protocol, you will find some sources (see links). The sensor will do this every 4.5 seconds +If you dare to use the IT+ protocol, you will find some sources (see links). The sensor always send every 4.5 seconds 5 bytes. The radio frequency is fixed at 868MHz. If the sensor can also measure the humidity, the value comes with it, if not then there is a fantasy value (= 106). Each sensor has an address coding. __Caution there are sensors that use a new address after the battery has been changed.__ Several sensors can also be evaluated in parallel decoding the address. 
-always 5 bytes sent. The frequency is fixed at 868MHz. If the sensor can also measure the humidity, the value comes with it, if not then there is a fantasy value (= 106). Each sensor has an address coding. __Caution there are sensors that use a new address after the battery has been changed .__ Several sensors can also be evaluated in parallel using the address. +It should also be noted that no negative values ​​are transmitted, as the temperature is always treated with an offset of 40 before transmission.
-It should also be noted that no negative values ​​are transmitted, as the temperature always receives an offset of 40 before transmission.+
  
 <code C> <code C>
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 ====Hardware==== ====Hardware====
-{{:tech:schematic_1.png?direct&300 |Schaltplan Seite 1}} +{{:tech:schematic_1.png?direct&300 |Schematic Page 1}} 
-{{:tech:schematic_2.png?direct&300 |Schaltplan Seite 2}}+{{:tech:schematic_2.png?direct&300 |Schematic Page 2}}
  
 ---- ----
  
-The following components are used as hardware:+The following components are used in the hardware:
   * 868MHz receiver module with PCB antenna   * 868MHz receiver module with PCB antenna
-  * ATMEL ATmega1284P + ENC28J60 for 100base-T+  * ATMEL ATmega1284P + ENC28J60 for 100base-T ethernet
   * microSD adapter   * microSD adapter
  
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 There is an inexpensive 868MHz RFM12 module for receiving (and, if you want, also for sending). There is an inexpensive 868MHz RFM12 module for receiving (and, if you want, also for sending).
 It is a '' Universal ISM Band FSK Transceiver '' and has already been extensively described elsewhere [[http://www.mikrocontroller.net/articles/RFM12|RFM12]]. It is a '' Universal ISM Band FSK Transceiver '' and has already been extensively described elsewhere [[http://www.mikrocontroller.net/articles/RFM12|RFM12]].
-Communication takes place via a normal SPI interface in 16-bit transfer. The setting options are so versatile that you get desperate at the beginning until you finally want to receive. Therefore, here is the init sequence that was successful for me:+Communication takes place via a normal SPI interface in 16-bit transfer. The setting options are so versatile that you get desperate at the beginning until you finally are able to receive. Therefore, here is the init sequence that was successful for me:
  
 <code C> <code C>
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 === PCB === === PCB ===
 {{: tech: sensorlogger_board.png? direct & 200 | Board with PCB antenna}} {{: tech: sensorlogger_board.png? direct & 200 | Board with PCB antenna}}
-The PCB was matched to the SP 2000 SW housing from STRAPUBOX. So that everything simply fits into SMD where it makes sense.+The PCB was matched to the SP 2000 SW housing from STRAPUBOX. So that everything simply fits into SMD components are used where it makes sense.
 When it comes to sockets (Power / Ethernet), I'm still a fan of thru-hole - because of the stability. The soldering took place again in the pizza pan as described in the c't Hacks. When it comes to sockets (Power / Ethernet), I'm still a fan of thru-hole - because of the stability. The soldering took place again in the pizza pan as described in the c't Hacks.
  
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 An antenna must also be connected to the RFM12 module. Usually 1/4 lamba so about 8.3cm. But since there was still space on the PCB, I dared to try a PCB variant in a meandering structure. There is also a nice design note from Texas Instruments (DN024). The result was a bit off, however, because the <m> epsilon_r </m> of my favorite PCB maker turned out a bit different in reality. The maximum gain was about 790MHz and could then be reduced to 868MHz with a final -6dB gain. This means that reception through concrete ceilings or walls is also feasible. An antenna must also be connected to the RFM12 module. Usually 1/4 lamba so about 8.3cm. But since there was still space on the PCB, I dared to try a PCB variant in a meandering structure. There is also a nice design note from Texas Instruments (DN024). The result was a bit off, however, because the <m> epsilon_r </m> of my favorite PCB maker turned out a bit different in reality. The maximum gain was about 790MHz and could then be reduced to 868MHz with a final -6dB gain. This means that reception through concrete ceilings or walls is also feasible.
 ==== Software ==== ==== Software ====
-The software was created with AVR STudio 6 and AVR-Dragon is on the handicraft table as a debugger. A UART I / F is on board as support, which then outputs the printf instructions on my MAC via a level converter and the RS232 / USB adapter without complaint. A command I / F also allows direct control via the same interface. A small web server is also integrated for normal operation. The entire package including Ethernet and SD support requires approx. 85K FLASH and 12.5K RAM memory.+The software was created with AVR STudio 6 and an AVR-Dragon as a debugger. An UART I/F is on board as support, which then outputs the printf instructions on my MAC via a level converter and the RS232/USB adapter without complaint. A command I/F also allows direct control via the same interface. A small web server is also integrated for normal operation. The entire package including Ethernet and SD support requires approx. 85K FLASH and 12.5K RAM memory.
  
 ==== Outlook ==== ==== Outlook ====
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 ==== Links ==== ==== Links ====
-  * [[http://hackaday.com/2011/06/13/reverse-engineering-wireless-weather-stations/]] IT + protocol description +  * [[http://hackaday.com/2011/06/13/reverse-engineering-wireless-weather-stations/]] IT+ protocol description 
-  * [[http://fredboboss.free.fr/tx29/]] IT + protocol description +  * [[http://fredboboss.free.fr/tx29/]] IT+ protocol description 
-  * [[http://gcrnet.net/node/32]] IT + protocol description+  * [[http://gcrnet.net/node/32]] IT+ protocol description
   * [[http://www.ti.com/lit/an/swra227e/swra227e.pdf]] Antenna Design Note DN024   * [[http://www.ti.com/lit/an/swra227e/swra227e.pdf]] Antenna Design Note DN024
   * [[http://www.mikrocontroller.net/articles/RFM12]] Receiver module description   * [[http://www.mikrocontroller.net/articles/RFM12]] Receiver module description
en/tech/sensorlogger.1602782246.txt.gz · Last modified: 2020/10/15 18:17 (external edit)

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