Project Objective:Develop an open source AIS Alarm that alerts sailors that a new marine vessel with AIS is within range
In the last post I published a video of the completed prototype of the alarm and announced plans to continue working on the firmware and user interface. In the meantime I ordered additional materials and today my friend and I cooked up a batch in his toaster oven. They turned out really tasty and I have the ingredients to make more :-)
I've revised the hardware design up to V1.0 but there were only the most minor of changes from the last post - basically a tweak to the faceplate to better ground it and a tiny adjustment to penetrations for the buttons. I made a substitution to the dual MOSFET (same manufacturer and footprint, slightly better specs) since the less expensive one I used previously was not immediately available.
In addition, I ordered a stencil and we used a toaster oven to reflow for the first time. However, the solder mask from the Chinese manufacturer of the PCBs did not extend between the pins of the 20 pin TSSOP or the dual MOSFET. We had to touch up bridging between pins on several boards but this went quickly and they have all tested OK. I looked back and found that some of my previous orders from China also lacked solder resist but all of the orders from OSH Park had the mask where expected. A review of the Chinese specifications shows that they will not meet the specified solder mask width in my design. These are the sorts of things you find when you change parts or manufacturers. A small change to the stencil and / or pin spacing may be in order to improve ease of manufacture.
Actually I might not have noticed this (but my friend did) and he also has a new stereoscopic microscope which shows such things in brilliant detail. I was blown away by it. Incredible. Another thing I must have...
The firmware has been refactored but I am still cleaning up and testing.
I plan to add hardware verification to the firmware at power up and continue testing.