Often an additional input used an index, which goes high when the encoder is at its ‘zero’ position: for our application this is less important. As demonstrated in the adjacent animation, the direction of rotation can be determined based on the input sequence. Incremental encoders have two outputs, A and B, which turn on and off with the rotation of the shaft. In this case the encoder needed to be able to control directional scrolling through menus and entrance into submenus an incremental encoder was chosen. The rotary encoder is the key interface for the hot plate controller. I added breakouts for all unused MCU pins for maximum flexibility.
Decoupling capacitors at all power inputs were also included. I connected a crystal clock, but in reality, the internal RC oscillator would likely have been sufficient for my purposes. The MCU requires minimal external conponents to function. The schematic is grouped into different functional areas. I tried to use best practice when connecting everything such as placing capacitors near every connector and IC power input. I much prefer the KiCAD built-in libraries which seem far less cluttered than those in Eagle. This was the first major project I used KiCAD for, so while desining the schematic I was also getting used to the new software. I went back multiple times during the design process to make changes to the pinout as physical layout demanded.
The benefit of doing this before designing the schematic is that you can group pins going to the same physical areas together and CubeMX will identify any conflicts with the layout. With my MCU decided, I loaded it into STM32CubeMX, an ST program which allows for graphical chip configuration I then designated pins for each device. This post will only cover the the controller board, with the chassis assembly and integration detailed in an upcoming post. Inspired by maker.moekoe’s project, I decided to recycle an old steam iron to make a hot plate that reflows SMT boards for speedy assembly and incredibly neat solder joints. Then components can just be placed on the board and the solder reflowed. Stencils can be purchased from PCB manufacturers which makes depositing an even layer of solder paste on all pads simple. Finally, the board enters an oven, all of the solder paste ‘reflows’, and all of the components are pulled into alignment.įor my small scale uses (only 1/2 boards needed per design) a pick and place machine might be a bit overkill, but a reflow oven could reduce assembly times significantly. Solder paste is dispensed onto the pads of the circuit board and components are then placed on the board with a Pick and Place machine. In industrial manufacturing, solder paste is used to completely automate the soldering process of surface mounted components. Over the past few months I’ve been designing quite a few PCBs and have been interested in ways to speed up assembly.
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