Schematic Prints & Draftsman Files
Draftsman files are multi-sheeted documents that contain individual pages that are assigned to particular types of board project production information.
Listed below are the schematic diagrams of the main circuits in PCB board as well as our PCB board assembly.
Schematic Prints
Pulse Sensor Circuitry
The heartbeat/pulse sensor provides an analog value between 0 and 5V. As the input to the microcontroller can only be in the range 0-3V, a voltage divider was added to scale down the value. This sensor is a stand alone sensor
Touch Sensor Circuitry
The touch sensor also operates on 5V, but the touch sensor provides digital output depending on if the sensor was touched or not. For this reason, we felt it was necessary to have a logic level shifter here to convert values from range for 5V to 3.3V. This sensor is a stand alone sensor
Temperature/Humidity Sensor
This sensor is placed on the PCB board. The SHTC3 IC is connected to capacitors to remove noise. The SDA and SCL pins can be used to pass data to the IC in order to acquire or read ambient data.
SAMW25H18 Microcontroller
This is the brain of the project. The SAMW25 module is based on Microchip's industry-leading WINC1500 Wi-Fi core combined with the latest ARM® Cortex®-M0+ based microcontroller technology.
Buzzer Circuitry
This part in conjunction with the touch sensor forms the SOS alert system. The active buzzer is connected to a B320A Schottky diode and the ground pin is connected to the 2N7002 IC which allows only one way flow of current. When the touch sensor is touched, a signal is sent from the microcontroller to the buzzer through "In"
Power Management Circuitry
In our project, we require two voltages- 5V and 3.3V to power our sensors and microcontroller. The LiPo battery provides 12V which is passed through this buck circuitry to get an output of 6V. We do this because it was easier to convert the voltage from here using just 2 ICs- LM111-MPX for 3.3V conversion and LM117-MPX for 5V conversion
Draftsman Files
After completing the PCB design, Altium CircuitMaker provides an option of automatically generating the Draftsman document required by the PCB production factory to generate the PCB. The image on the top left is the Top View of the PCB which shows the number of components, the size of the components and the positioning of the components. The image on the top left shows the layer stack of the PCB we used to design our PCB and finally the image below presents the projected look of our PCB as per Altium.