Table of Contents
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.
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
Experiments
This section is more for documentation.
Temperature Drift
- 04/01/15 23:04 - AB → AH6,
- AH6 reporting T-6
- AB reporting T25
- 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
- Comparing the 2 pictures
- 1st image frequency difference was 27 pixels
- 2nd image was 21 pixels
