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:
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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. |
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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. |
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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. |
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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