Hey! New here, I’ve been a lurker for a while and decided to make an account and ask a few questions.
About a year and a half ago, I came up with an idea for a tool that I could use at work (commercial HVAC technician) to be able to calibrate and diagnose issues with Electronic Expanion Valves. These “EEVs” use a stepper motor to open or close valves to meter refrigerant. I’ve dabbled with Arduino and breadboards before this, and was finally able to come up with a working prototype that used numerous premade pcbs (boost/buck converters, Arduino nano boards w/ breakout pcb, external battery life indicators etc) obviously having this many separate boards all being manually wired together was not a good option as it was fragile and buck/boost converters were melting if I hooked up to an EEV that drew a tad to much power. I dabbled with having guys on fiver make me some actual PCB prototypes, but after spending 5-700$ on having boards ordered an assembled through JLPCB, I still didn’t have a working prototype, which leads me to the old saying “if you want something done right do it yourself” so I downloaded kicad, started watching youtube videos, and began prototyping simple PCBs until I started getting the hang of it. Well, 7 months after downloading kicad I have a pretty complex PCB using an ATMEGA328P-AU & an A4988 stepper driver IC. The atmega chip produces a contact 330Hz square wave for the a4988, and also controls the button logic for enable/direction & speed controls MS1,2 & 3. The board is powered from a 3S AAA 3.7v battery pack delivering 12.4VDC to the PCB, an ATTINY and a low quiescent linear regulator is used for turning the device on an off, the ATTINY stays in sleep mode until the button connected to one of its pins is pressed and held for 1 Second, it then wakes up, and outputs 5v to the gate pin on a SOT223 2N2222 Transistor that makes contact between battery ground, and the ground plane on the PCB, enabling 12VDC to the rest of the board. Another 1 second press will then shut the board off.
My real question here is since I also dabble in Cad, (solidworks & shapr3d) I’ve designed a case for this project, but I want it to be sleek, and durable. So I’d like to implement the use of a custom membrane switch keypad. I’ve looked at some websites and seen I can have them prototyped for around 300 USD. Has anyone had a custom membrane keypad made? I have & can use photoshop to design the button graphics, and can design the schematics for the buttons aswell, would this cut down cost? What is the process of having these keypads made? Any suggestions for an easy to work with company for making these?
Thanks.