Week 14-15, 19 Nov till 28 Nov

It is reading week! Exams are so around the corner. Within these 2 weeks, besides studying, I have finally finalized my schematic design and PCB, and sent out for fabrication.

Changes of schematic diagram
Compared to the previous schematic diagram, this version is more complete, with all the power supply circuits and communication (bluetooth) circuit embedded as well. Basically, 3.3V power is supplied to the buffer device and the bluetooth device, whereas 5V supply is fed into the PIC, air pump and vacuum.


(click here to download the schematic diagram in pdf format)

I have also completed the PCB design and sent out to NUS PCB fabrication facility. Hopefully by this week, all my components are here with the PCB as well, so that I can start soldering them on the board. Below shows my PCB Boards:

Main circuit


Connector board
This connector is used to interface the battery holder, the air pump and vacuum. They are not connected to the main board so that it is flexible to position them anywhere in the armband.


Sensor board
The sensor is mounted separately onto this board, so as to provide flexibility when placing it into the armband.


LED board
The LED board tis to be mounted at the outer side of the armband, to show the pressure level from the input. All the LEDs are aligned in a line. A stronger pressure will light up more LEDs, and vice versa.


Things to do next
For now, my next task will be to finish soldering the circuit as soon as possible once the board so that I can start tuning the control system. Since I am left with about 2 weeks before the CiA competiton in Taiwan, I intend to finish soldering by the middle of next week and start on tuning software after that.

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