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  • Author Author: fmilburn
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AIS Alarm - PCB Version 0.1 Arrived

fmilburn

Project Objective: Develop an open source AIS Alarm that alerts sailors that a new marine vessel with AIS is within range

 

The PCBs arrived today but unfortunately I was slow in ordering the more obscure parts for the design and they have not yet arrived.  This blog post will describe populating the board with the parts I have on hand and first impressions of what will be needed for the next revision.

 

Here is a photo of the board as it currently stands:

image

It looks pretty sparse now that it is off the breadboard and onto a PCB.  I am soldering by hand using an inexpensive reflow station for the SMD components.  The parts that remain to be placed are the buzzer, dual MOSFET, and the bright 5 mm right angle LED.  I've been able to test the switches and LED indicators and they are OK.  All the traces look OK.  The board is programmed using the header on the far left.  The inside header will connect to the dAISy radio via ribbon cable.  Here are the observations so far that will need to be addressed before the next revision:

  • The boards were attached in the original panel by tabs with mouse bites that had to be taken off with a dremel tool for it to fit in the enclosure.  I will look at V-cuts  or possibly making the board slightly less wide in the final design to avoid this.
  • The board is going to slide in over the radio in the enclosure.  There is very little room between the indicator LEDs on the right and the board with the radio below it.   This prevents the use of a connector and will require hand soldering of the ribbon cable between the radio and the Alarm PCB.  I knew this was going to be a problem and am still looking for a way around it.
  • The MOSFET footprint is pretty small and will be difficult to hand solder.
  • Should add some test points.
  • The button switch on the left needs to be moved to better clear the enclosure.

 

A funny thing is that most of the issues are mechanical in nature and I am a mechanical engineer.  I find that the mechanical issues are the ones I usually iterate on the most when it comes to the PCB.

 

The remaining parts are expected by Friday but I am expecting guests for the weekend so probably won't get back to this until early next week.  But it looks like this will be good enough to iron out most of the hardware issues as well as make the next upgrade to the firmware.

 

Past Posts from this Project:

AIS Alarm

AIS Alarm - The Process

AIS Alarm - Prototype Hardware

AIS Alarm - Timers and GPIO

AIS Alarm - Prototype Code Outline

AIS Alarm - UART

AIS Alarm - First AIS Messages

AIS Alarm - First FRAM Storage

AIS Alarm - Debouncing Momentary Button Switches

AIS Alarm - FRAM Ring Buffer

AIS Alarm - Schematic

AIS Alarm - PCB Version 0.1

 

References and Links:

WEGMATT LLC - dAISy AIS Receiver - low cost AIS receiver

Texas Instruments MSP430FR2xx FRAM Microcontrollers - Post No. 4

TI MSP430FR2111

Maximize the Sound from a Buzzer

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  • Frank,

     

    Nice clean looking board.  To bad about the outstanding issues. Those tiny MOSFET packages are tough, but with a little practice I was able to hand solder those.  Good luck there.

    One the issue of ribbon cables with little access space for connectors, here is a little trick that I have done in the past.  I mount a standard, thru-hole header on the board edge, with pads on the top and bottom of the board. Depending on the board thickness you might have to bend the leads to get a tight fit.

    imageimage

    You can then use IDC connectors on ribbon cable to plug into the headers.

    Gene

  • in reply to genebren

    Hi Gene,

     

    Thanks for the feedback!  Below is a photo that will give you a better idea of what I am up against by trying to use the existing dAISy aluminum enclosure:

    image

    As you can see, the new PCB slides (almost) inside the dAISy enclosure and is on top of the radio.  I was careful to keep my microcontroller and the buzzer as far as I could from the radio itself.  The cutout in my PCB is to clear the BNC connector for the antenna at the front right of the enclosure from this angle.  The right pushbutton impinges on the case but I can move that.  But there is almost no room under the LED indicator.  To compound the problem the dAISy header is also under that LED indicator.  I can see a couple of options:

    • Swap the button switches with the LEDs to give more clearance (Doh!!!  Should have done that to begin with)
    • Use one of those indicators with dual LEDs inside the same casing which would not be as tall.
    • Use a different case

    I like your idea - I think I could also use one of the JST style connectors.  For now I can hack something together and work outside the case.

     

    Appreciate the comments,

    Frank

  • in reply to fmilburn

    Frank,

    That is a very tight and very clean little package there.  On the LEDs, you might free up some space with some bright, surface mount LEDs (side view).  You could do small cut-out windows with plastic windows to show the indications. I have also used light pipes to direct the light through the enclosure.

    Your project is moving along nicely.

    Gene

  • in reply to fmilburn

    That clever idea of might also work for the LEDs.

    If necessary you could notch the pcb to bring them further back from the edge, which allows normal 3mm LEDs to be used.

     

    if you want to stack them vertically, one on the bottom, and one with bent legs on the top side would give you the clearance required.

     

    Mark

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