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Forum Index : Microcontroller and PC projects : Swipe-A-Mite 1A...
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9594 |
Here is my latest effort. It is a self-contained key-less entry system for low to medium security applications. 
It uses type-4100 125kHz RFID tags or cards for entry, and the Micromite does all the work. I have yet to write the code, but preliminary tests of the concept have worked well, so that will be next. Tags and cards can be had on eBay for about 30c each - dirt cheap. The system uses a 1.8" LCD for a display, and has a 10A relay for switching a door strike or maglock. Piezo sound output, serial and I2C outputs if needed for controlling external equipment, and a trigger line. IR remote control interface for the admin mode, so you can easily and painlessly learn in new tags and delete old ones etc. This is achieved by swiping a master tag or card which has the admin access rights. This is programmed in by shorting the ADMIN LEARN jumper. The system otherwise ignores the remote control. It's designed to fit inside a Jaycar case(HB6082 with a clear lid, to which is fitted a label to cover pretty much all the top cover but the LCD. This little case is nice, as the clear front plate is screwed on from the back, meaning you would have to break the front of the case to get into it, meaning that it is reasonably secure as MOST people won't want to break the case. The relay is there for backwards compatibility, but I plan to use either serial or I2C commands to an additional controller inside, which would then release the door. This means that even if you DID break open the case and short out wires to try to open the door, it won't - you must send the correct serial or I2C code sequence to open the door. This idea is not fail-safe in that respect, but if you could break the box open and short out the relay contacts and open the door, what's the point in having the key-less entry at all, if you see what I mean..... Case is NZ$10 from Jaycar, RFID module and antenna coil is NZ$6, LCD module is NZ$5, PIC32 + other passives would be about another NZ$10 or so. Entire unit could be built for about NZ$30, or US$20 with today's exchange rates. If anyone is interested, I will update this thread as I build the prototype, and I will probably be offering this as a full kit(with case) from my website once I have everything running right. The remote I plan to try to use costs a whole NZ$1.50, or about $1 in American currency. Smoke makes things work. When the smoke gets out, it stops! |
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CircuitGizmos Guru  Joined: 08/09/2011 Location: United StatesPosts: 1427 |
That looks great! What is the cut out for? I have some of those remotes. I spent a very short time seeing if they would work with the 'mite. I think that it was early on when IR/remote code was being developed. I wasn't able to receive commands. From what I understand the remote is supposed to be able to transmit different codes, like a universal remote does. If you get it to work, Grogs, post here about what it took. These are dirt cheap and would be easy to use with a micromite. We just need to know the right combo of buttons to get it to transmit "Sony" codes. 
Edit: Press and hold "mute" is what I understand cycles through codes. Eventually Sony shows up? Micromites and Maximites! - Beginning Maximite |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9594 |
Hi CG. 
Yes, they are universal. Being so cheap, they might not actually be suitable because of that - difficult to get it into Sony code mode unless you have a Sony TV to set it up on kind of thing.... We'll see. The cut-out hole is for the wires to pass right through the back of the case, and through the cut-out hole so you can connect wires to the relay and power supply T-blocks. Basically, fit the PCB to the box, then use a flat-blade bit to bore a hole through the back of the case using the cut-out as a guide. Smoke makes things work. When the smoke gets out, it stops! |
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vegipete Guru Joined: 29/01/2013 Location: CanadaPosts: 1129 |
How are you making those oblong holes for the relay? A bunch of round ones in a row? Does the board house have any objections or issues? (SprintLayout, right?) Visit Vegipete's *Mite Library for cool programs. |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9594 |
Yes, the slots are made by placing several holes of the same size in close proximity to each other. Weather this is actually drilled at the factory, or converted to routed holes is something I don't know, but I CAN say that the PCB house(Shenshen2U) have never complained or rejected that arrangement, and I have had many boards with slotted holes like that done there now. Yes, Sprint Layout 6. Smoke makes things work. When the smoke gets out, it stops! |
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MicroBlocks Guru Joined: 12/05/2012 Location: ThailandPosts: 2209 |
In diptrace (which is free for smaller pcb's) you define a 'pad' very easy. 
Microblocks. Build with logic. |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9594 |
I do remember emailing the Sprint Layout guys and asking them about slotted holes, but that is how they told me to make them. Some PCB houses will refuse that idea, but it does depend alot on what you are trying to do. Large slotted holes tend to be a no-no, but very small ones don't seem to cause most PCB houses to grumble. Smoke makes things work. When the smoke gets out, it stops! |
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VK6MRG Guru Joined: 08/06/2011 Location: AustraliaPosts: 347 |
Hello Grogster, Is this something that you would look at selling? Maybe a good article for silicon chip magazine..... Its easier to ask forgiveness than to seek permission! ............VK6MRG.............VK3MGR............ |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9594 |
That is the plan. I have yet to write all the code to make the unit work, but the concept is not that difficult, so I don't foresee a great amount of issues there. ...famous last words........ The idea originally was to make it using through-hole parts, with an eye to a SC article, but I just could not squeeze everything into that case I wanted to use without going to SMD. The PIC32 is an SOIC version though, so most hobbyists can still solder these OK.(they tend to be frightened off by the 0.6mm SSOP and 0.5mm QFP's though, which is a shame) I am final checking the PCB layout tonight, then I will order the PCB's so I can get to work on the prototype. Another object of the exercise, was to try to make the unit cheap and affordable for the likes of a SC article. I think I have managed to do that reasonably well, and the tags and cards for the system are certainly cheap enough at 30c each!  Smoke makes things work. When the smoke gets out, it stops! |
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