This was a relatively simple design to digitize breathing belt sensor signal and send the data to a computer. The nice feature was a wireless Bluetooth interface to the computer. I used an existing Bluetooth module in this design and wrote Java test program to receive the data. The software was developed by the client who was a SW programmer.
This tag combined the functionality of an RFID tag operating on 433MHz under 18000-7 protocol and a proprietary RTLS (Real Time Locating System) functionality.
For this product development I completed the hardware design including component selection, schematic capture, PCB layout, firmware architecture, initial prototype assembly and testing.
It was a challenge to make the 18000-7 and RTLS functionality coexist. There were number of timing conflicts that needed a solution that would result in low power while maintaining responsiveness.
I was a member of the firmware development team. I acted as the scrum master and also developed some of the code.
This was a wildlife tracking transmitter, used for tracking bats, operating at around 150MHz.
The prototypes were hand made by placing Kapton tape upside down over a printout of a PCB layout. The parts were put on top of the sticky side of the tape. The 30AWG solid wire was used to make connections. When all the parts and wires were in place, I put dabs of solder paste over all connections. At the end I reflowed the solder with the use of hot air tool. A number of prototypes were successful with this method.
With the help of a PCB house the final double sided PCB was made on the thin somewhat flexible substrate used inside multilayer PCBs.
With battery and crystal the transmitter weight just 1 gram with a lifespan of about 1 month.