Project Objective:Develop an open source AIS Alarm that alerts sailors that a new marine vessel with AIS is within range
With the schematic complete it was time to design a PCB. This blog entry will outline the PCB design and layout along with the primary considerations.
The "L" shape of the PCB is a direct result of the enclosure that will be used and is necessary to avoid interference with other components already inside the case. The dAISy radio receiver will reside underneath the through hole headers on the lower part of the PCB. This places the noisier components away from the radio on the upper half of the board and reduces noise (I hope). As stated in the previous post, a double footprint was used for the buzzer so that both through hole and SMD components can be tried out.
I used KiCad for the PCB design. No real reason other than a friend was using it when I got started in electronics so that is what I have been using as well. The resistors and capacitors are 0805 and the microcontroller TSSOP. I enter the footprints for new components myself based off of the datasheet. Often I will lengthen the pads a bit on something like SOP components to make them easier to hand solder. Looking at Q1, the dual MOSFET, I probably should have lengthened those pads.
This board is labelled Version 0.1 as final components have not been chosen and the enclosure may change. The components in this design are what was on hand or readily available. It is being fabricated by OshPark and should be back in 10 days or so. In the meantime the firmware will be modified so the board can be tested as soon as it is received and populated with the components.