Researched PID control algorithms for precise thermal regulation. Switched to a new MOSFET to better handle power delivery, and drafted the initial firmware to run the temperature loop.
Looked at different mosfets to turn on the heating film - using PWM i can vary the temperature. i’ve also completed my schematic
This is my initial research into temperature sensors, mossfets and microcontrollers that i’m going to be using in this project. i found the TMP117 digital temperature sensor to best fit my project needs as it can run on low voltages which is important as i would be using AA or AAA batteries to run this board. For my microcontroller i found the ATTiny85 to also run on low voltages, which is also easy to use.
Created the firmware, i used the Arduino IDE with the keyboard library as i was familiar with it and thought it would be more simple.
In order for parts to fit comfortably, i opted to using compliant mechanisms to suit most or all tolerances, this fixes most problems i could of had in the future with parts not fitting together. As seen in the pictures theres slots in between the model, this allows the plastic to adapt to the different sizes
Created the basic bottom for the enclosure
Fixed some tolerance issues, and made sure parts fit together as expected.
Started the Enclosure, i used Fusion360 to design my enclosure around the PCB, As seen i the picture the goal of this enclosure is to keep the same small form factor as with the PCB. initially i was going to slant the whole enclosure by around 6 degrees to create a more ergonomic design, but found that this would create much more extra work when creating the holes for the switches and encoder so i scrapped that idea.
Finishing the actual PCB and updated the schematic, In this 2h session i had to slightly change the initial schematic to reduce dead space within my PCB by adding another switch, this also adds extra functionality. I wanted my design to be as compact as possible to make the PCB design sleek and minimalistic, i achieved this by careful placement with consideration of PCB traces. - adding to the minimalistic look i changed the mask colour to black, this took alot of googling as you can’t just select what colour you want - i had to go to file > Board setup > Physical Stackup > F.Mask > Black
Finished my PCB schematic, i slightly deviated from the tutorial to add a rotary encoder
