MicroSeeker Circuit Boards

Some people have asked me why I publish so much information about my sub. The answer is two-faced -- I like to share, and I think information like this is valuable. I also don't consider any of the mechanical and electronic stuff I am using to build the sub to be particularly important. The sub is simply a test-bed for the software I am writing. The software is where my real interest lies, and where most of my research effort will be going once I have a viable platform.

The old circuit board (revision 1) looked like this:

(Note that all the pictures on this page are clickable to get larger versions...)

It had a BasicX-24 main processor, a couple MotorMind B serial speed controllers, an ADXL202 tilt sensor, a Dinsmore analog compass, and a Motorola MPX-4250 pressure sensor. It also had a daughter-board with a PIC 16F84 to control the tilt servo.

The new board (revision 2) is actually a pair of boards, since the new "brain" computer has a different footprint than the old Helio I was using. The board on the left (the main board) below goes on top, and the one on the right (the sensor board) goes on the bottom. I have a set of 1" spacers between the boards, and the bottom board is spaced 1/8" off the base mount on the sub.

A special thanks goes to HVW Technologies, who printed these boards for me...

Here is the main component list for the main board (I've left off caps and resistors):

PIC 16F877 Microchip main micro-controller (main board)
PIC 16F876 Microchip servo micro-controller (sensor board)
DS-275 Dallas serial TTL/RS-232 level converter chip (main board)
MPX4250 Motorola pressure sensor (sensor board)
HMR-3300 Honeywell 3-axis digital compass with tilt chip (sensor board)
LM2940 National Semiconductor 5-volt regulator (main board)
SRF04 Devantech Sonar (sensor board)
TI 754410 L293D-compatible dual-motor h-bridge (main board)

And some pictures of the finished boards:

Here they are, mounted to the new chassis. For the keen-eyed, no, that's not a TI 754410 in the h-bridge socket -- its an old L293D I had lying around. The only 754410 I have is in my mini-sumo Seeker II, so this one will have to do for now until I can order a new one.

The big chip is a PIC 16F877, and the little 8-pin chip just above it is the Dallas DS-275 serial chip.

Here's the sensor board. It has, starting at the left, the HMR-3300 digital compass, the SRF04 sonar, the MPX-4250 pressure sensor, and the PIC 16F876 servo controller. There are a couple empty pin holes sets in this board -- those are for the connection wires to the top board, which I haven't finished yet.
The sonar shown above isn't much good the way it is right now. I will be de-soldering the transducers from the board, and soldering a 4-wire ribbon cable in their place. The ribbon cable will lead to these two transducers, which have a solid aluminum face. These will be mounted in a tube like the one shown below.
Here's one of the sonar tubes. This thing (along with the other one) will be in the nosecone, facing down, with the above transducers silicone sealed in place.

I'm not 100% positive it will work, but that's what proof-of-concept research is all about...

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Questions and comments can be sent to Jon@huv.com