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====== RFM69HW Temp Management ======

===== Idea 1: Crystal Oven =====

==== Components ====

  * RFM69HW
  * Moteino or another micro
  * 2 Resistors (10ohms)
  * Mosfet

==== Design ====

  * 2 resistors in parallel lying over the RFM69HW crystal acting as heaters
  * Mosfet is used to connect the resistors to ground (they are connected to VCC as well) to complete the circuit and heat up the crystal.
  * To control the temperature we use PWM to turn the mosfet on and off, the hotter we want the more often we turn the mosfet on.
  * The control system uses a PID loop

==== Current Implementation ====
  * Using the PID v1 library on the arduino (using a moteino)
  * Measuring temperature with the onboard RFM69HW temperature sensor
  * Working well using a setpoint of 20C to test.

{{:ideas:15351933030_139d7c1206_o.jpg?300|}}
{{:ideas:15513869606_518273199b_o.jpg?300|}}

==== Possible Improvements ====
  * Improve heating efficiency with better insulation
  * Tighten the PID loop
  * Use an external temperature sensor which maybe more accurate

===== Idea 2: Adjust Freq to Temp =====

==== Links ====

  * [[https://lowpowerlab.com/forum/index.php/topic,357.0.html]]

===== Experiments =====
This section is more for documentation.

==== Temperature Drift ====

  * 04/01/15 23:04 - AB -> AH6, 
    * AH6 reporting T-6
    * AB reporting T25

{{:ideas:abtoah6_cold.png|}}

  * In this screenshot its possible to appreciate the difference between the frequencies of the nodes, currently AB is only rx'ing 20% of AH6's beacons most likely due to the frequency difference.

  * 05/01/15 07:34 - AB -> AH6 
    * AB = T24
    * AH6 = T1
{{:ideas:abtoah6_warm.png|}}

  * Comparing the 2 pictures
    * 1st image frequency difference was 27 pixels
    * 2nd image was 21 pixels

{{:ideas:rxovertime.png|}}
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