Mini digital scale with micro USB port and Bluetooth Smart module
Please only apply if you have experience with all the components/protocols listed in this project. I am able to work with a freelancer only from Europe or USA, as I will need to ship electrical components. You need perfect written English for this job. You have to be detailed and 100% accurate.
Imagine a digital luggage scale; I want a similar small device with a micro USB and a Bluetooth data outputs. When I pull the scale, it sends the data to a connected device via USB or wireless.
The project based on a PCB with strain gauge Wheatstone bridge, a battery power supply, an ADC with PGA, a microcontroller, a USB port and a wireless transceiver. The data are sent to the receiver (phone, tablet, laptop), and the data are processed and stored in a software. The transmission of information is one-way only, the receiver device does not control the scale. Turning off and zeroing/reset will happen manually by a button on the scale body. The USB port might be there for recharging the battery and update the MCU software as well.
I am a mechanical engineer with a basic knowledge in electronics. In the last few weeks I read every detail of similar projects and collected all the appropriate information and made a list of recommended components, but I will need help with finalising the development steps and the final BOM.
I found ready-made solutions for high-resolution scales, with recommended Analog to Digital Converters, CPUs and Development Kits. In addition there are circuit diagrams and C source codes available on the Internet for free, too.
I need you to supply the proper flow charts, circuit diagrams, and C source codes of the project. (Free Internet stuff can be used for these.)
I need a working prototype (I can build it with online supervising) on a solderless breadboard with an MCU development kit, which will be able to connect to different 4-wire strain gauges in order to test the mechanical assembly.
Finally, I need a Gerber file for printing a PCB prototype.
I will purchase the necessary components in order to be absolutely able to work in parallel, and my freelancer will get them by a courier.
I will then refine the software for different devices (phone, tablet, laptop).
So I know that such a simple, 5-dollar digital luggage scale is not new to the world, and implementing a USB port and a one-way wireless module is also doable. However, I have never done an electronic project like this and therefore help is needed.
I need someone who is very good and confident at this topic, and if any part of the project is unknown to him, he is willing to expand his knowledge with it.
Someone who answers my questions, explains the answers, and oversees the development of the project.
There will be some online chat meetings, but there will be more of individual work.
Proper documentation is very important (!), because I want to understand and learn all the steps of this product development.
I estimate that around 30 hours of your time needed for this project, this is why I determined the $300 budget.
Please apply with confidence if you have a professional experience.
Regarding your cover letter: please respond to my key requests, and include references of equal/similar projects.