British Engineering Systems

Here it is…..

peter — Sat, 10 Oct 2009 00:39:05 +0000

PLEASE NOTE FOR EVERYONE’S SAFETY: I present this as a basis for your own work and not to be directly copied as there are no doubt design flaws. I do not claim it is physically, physiologically or psychologically safe to use or that I take no responsibility for any injury, loss or death or anything else that may befall you, good or bad, if you decide to use this. This is provided with the understanding that if you use it you know what you are doing and understand the dangers and safeguards that should be used when dealing with electronics and the soft squishy and often wet bits of humans and that you take full responsibility for your actions. Electronics and moisture generally are not good when mixed so know what you are doing. There are design and construction procedures for equipment to be used with humans, please find out what these are and follow them. Also please follow all appropriate procedures and laws applicable to your location.

All that said here is the Hardware and firmware.

vibe-small.zip

edit: here is the contents of the EEPROM eeprom.zip

(anyone with any experience of open source licensing, please tell me if I have done it right)

I have not included the bootloader for 3 reasons:
1) It’s not required to make the thing work
2) I recently went through it and found some bugs so its not working at the moment
3) I am contemplating replacing it with one from sparkfun

Also in this bundle I have not included the PC software since that hasn’t been commented up yet.

First Prototype unit finished. Most spiffing!!

peter — Wed, 30 Sep 2009 22:17:21 +0000

As you can see one shiny blue box filled with magic.

As soon as I can work out what I need to do to make all this open source and easy for people to build I will post info. Schematics and layouts have been tidied up for release, code still needs comments and everything needs to be slathered with licence thingamajigs.

just need to build a few more units for beta tester(s)

Apoint of stability.

peter — Sat, 26 Sep 2009 14:21:50 +0000

Right. board populated with 4 mistakes, one transistor round the wrong way, one cap is too small, one track going to the wrong pin of the PIC and the gain resistor of the sensor head-amp a bit too low. Software finished.

Mark 2 PCB

peter — Sat, 12 Sep 2009 16:04:32 +0000

Well after a few problems with the first issue of the PCB the redesigned board has been made. Improvements include a smaller size, smaller USB module, more suitably sized uC

As you can see it is being populated by parts scavenged from the first PCB and is not quite finished. The more astute views will also not the lack of an op amp which will be on a very small board attached tot he back of the sensor and should help reduce some of the noise issues.

The project is still crawling along…

Wobble found. Design mod required. Oh posterior!!

peter — Mon, 04 May 2009 18:07:36 +0000

The oscillating op amp was down to cable impedance I think. In any case the answer is to put the strain bridge amp in the little blue box thus turning said cuboid into a mast head amplifier (no pun intended). while thinking about this i wondered about putting a uC with an ADC in there too and then just have a master controller with a network(maybe I2C/SPI or a PAN radio net) that would allow any add on you like to be put onto the net and involved in input or output.

Further to all this i would also like to have some real intelligence (def:using past experience to evaluate current experience to predict future experience and modify actions appropriately) in the thing, a bit like the SaSi to allow the user to decide which actions they like and which ones they want to have less often.

That of course would be a total redesign.

However if I am to redesign it from scratch I will use a touch screen OLED display for user interface and write all the source code in C on an AVR.

Delays delays delays. Just as well I don’t design these things for a big company.

Population: complete, Fault chasing: still in high speed pursuit.

peter — Wed, 08 Apr 2009 19:36:59 +0000

As can be seen in the picture below i have finished populating the first board.

(ignore the soldering blocks behind, my bench is currently covered with jewellery making stuff and vibrator making stuff)

faults so far found:

Power transistor not connected to the correct pin of uC
Tracks to voltage regulator end before they arrive
Opamps wired up back to front
pressure transducer acting as a theremin so something is wired up a bit wrong.

Always happens though, first PCB version never works. Looks quite professional though!

Population growth.

peter — Sat, 04 Apr 2009 14:56:57 +0000

Apart from the fact that I would appear to have forgotten to order some of the bits (or I have an envelope of them somewhere safe) The population of boards is coming along. as can be seen in the photo below.
So far I have noticed 2 minor screw ups in the design and a few bits that can be optimised. That’s what happens when you make PCBs. You spend a day looking for faults and then you find them within three seconds of open the envelope of boards.

With a bit of luck it will all work once the rest of the bits arrive.

Little green boards.

peter — Thu, 02 Apr 2009 16:45:31 +0000

Finally the boards have arrived. now to populate them

The grass is cheaper on the other side

peter — Thu, 05 Mar 2009 18:04:38 +0000

while I was looking at the PCB design I felt it was a bit wasteful of space so I started from scratch and redid it. it is now just 3.5″x1.85″.

After looking for a board house to make up PCBs for this little endeavour I found that crazily if i get them made in the UK there are few people with on-line shops for that sort of thing. if I go to mainland Europe the best I can hope for is still £50+ but if I use Sparkfun’s little side company, BatchPCB, the cost drops off enormously. They only charge $2.50 a square inch plus $10 and then postage. What is crazy though is that it is actually manufactured in china. so my design goes to America, where it is then sent to china for production, then the board goes back to America and then from there to me and that’s cheaper than going down the road to get it done!!!

anyway, boards are now ordered and should arrive sometime this month.

Incremetal progress

peter — Sun, 01 Mar 2009 12:43:42 +0000

Well after much faffing around I have finally finished the first draft of the PCB for this thing.

Its not pretty or well laid out but with a bit of luck it will work.

Getting there….