This undress alert is for my thirteen-year-old son suffering from autism

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Scott still has problems with the toilet, and because of his limited communication, he takes off his clothes when he is in his room. This does not end, every time, very well. We always keep an eye on him, but I thought it would be useful to be promptly informed when he undresses.

The challenge, as always with projects for children with special needs, is to build a safe device that will not hurt them and that they cannot swallow anything.

The Idea is to sew a transmitter module in each of his sleep trousers and attach a cord with Velcro between the electronic and the shirt. If he try's to remove the shirt or the pants, the switch will be pulled over the an the receiver will beep. The whole thing will work over 433Mhz. I will design a small PCB witch will be driven by a Cr2032 3V battery. It must be so small that it does not bother when Scott sleeps.

The prototype will be built with a Digispark USB Development Board - Digistump based on an Attiny85 and a 433Mhz RF module.
What will happen, when you have not noticed that he has pulled off his clothes? You have to clean the whole room.
We have already installed a security cam, but in night mode, it's difficult to see, if he is still dressed. I think this little device will make our life again a little bit easier.

  • 1 × attiny85 Microprocessors, Microcontrollers, DSPs / ARM, RISC-Based Microcontrollers
  • 1 × 433Mhz tx module
  • 1 × 433Mhz Rx module
  • 1 × Small end switch
  • 1 × Cr2032 Batteries and Battery Accessories / Batteries

View all 8 components

  • The USB Powered Receiver Is Ready

    Alain Mauer09/19/2019 at 17:27 0 comments

    And here it is in action

    When triggered, It beeps a few times and the LED's will show you, that there was an activation. You have to reset the led manually.

    The quick build:

    fist a 3D design in Sketchup 8

    Lasercut parts

    All together

    Little update:

    Had to add an external antenna to increase the range. Being a designer is really not my mojo :) 

  • Building A Second Prototype

    Alain Mauer09/15/2019 at 17:55 0 comments

    Working on the second one. This time I use an attiniy85 and  an SOP8 to Dip8 adapter.

    The whole thing is now a poor man's flexible PCB for wearables :)

    It will be a removable version but I have to ameliorate my sewing skills.

  • Status Update After A Clean Room Week

    Alain Mauer09/11/2019 at 06:43 0 comments

    As mentioned in the title, yeah, it works.So what are the first Results:Each time the pants were removed, the system informed us.Two times, it did not work, but I saw it on the camera, so nothing happened. First, I thought, that there is a problem with the transmission, so I installed a second receiver near the room, but this was not the problem. 

    It's a mechanical problem. When he removes the pants, with the left hand at the back, the tension to activate the switch is too weak. It's not really a problem, because 10 times out of twelve it worked.

    I've already started to build the portable receiver. It won't win a beauty contest, but it works.

    Working now on the enclosure and a clean wiring. Will update the receiver part in the "BUILD INSTRUCTIONSafter that.

  • Successfully Tested Prototype

    Alain Mauer09/07/2019 at 10:27 0 comments

    Yeah it works.

    This version is sewed to an old pants for test and and my son carried it, in the night. I got 3 alarms.Two in the evening and one this morning at eight o'clock. Each time I was there in time, to change his diaper or to put him on the toilet, to avoid a catastrophe.

    Even if this works like it should, it's not a good idea to attached it this way to the pants. I would need to put one transmitter on each one, and they had to be water proved and washing machine resistant.

    So I think, some kind of belt will be the solution. I will now transform a pair of pants with this system, so that it will help us for the next days, and I will concentrate on this belt stuff.

    I sew a small tube out of fabric. First I used jeans from an old pants, but is not very elastic, so I switched to an old shirt.

    The electronic was hot glued on a small piece of foam an with the help of duct tape isolated.

    the elastic band was fixed on the other side. The tension was just not big enough to handle the switch.

    Then the tube was sewed to the pants. same here, the tension did just not activate the switch.

    And here the whole thing on the test subject :)

  • Back To The Pull Switch

    Alain Mauer09/07/2019 at 09:51 0 comments

    My first Idea was, to use a micro switch and I came back to this Idea.

    I just changed the design, to make it simpler to use and my son will not detect that we there is something manipulated by us. I analysed, what happens, when he removes his pants, and I saw on the surveillance video, when he removes his clothes or when he goes to the toilet, that he has to pull sideways on the pants to remove them, so I decided to try something with a pull switch.

    Seems to work.

    I use a micro switch, and put a small protection over it, so that the cord will not be blocked in the foam and fabric. A small piece of PVC bend with heat will do the job.

  • Transmitter Prototype II

    Alain Mauer09/07/2019 at 09:30 0 comments

    Ok next try.

    I modified the software and the transmitter works now on interrupt. On interrupt it transmits two times the code, and goes to sleep, until the next interrupt. The circuit takes in standby 0.14uA. I can live with that and the CR2031 should last for 10 years ins standby. Transmitting takes about 0,7mA for a very short period

  • The Receiver

    Alain Mauer09/07/2019 at 09:21 0 comments

    The receiver was very easy to build. I used one of my Arduino QP 

    and I connected a simple 433Mhz Rf receiver module to it and a a piezotransductor
    A few lines of code, et voila.

  • First Prototype....Fail

    Alain Mauer09/07/2019 at 09:16 0 comments

    The attiny85 runs now at 1Mhz. I removed all the parts of the digistump, so I could use it as simple attiny.e

    The pillowpart should be attached to the pants, and the 2 neodyms with the Shirt in between. The basic idea behind this was, that when the shirt or the pants are removed, the 2 contacts jump together and the microprocessor transmits a code. then it goes to sleep. 

    The Idea was not bad, but I forgot en unknown variable in the scenario: My son :)

    He saw, that I attached something to his shirt and immidatly he pulled on the two straps, so that the system was disarmed.
    Now I know, that was not the best plan. So let me sleep a night over it.

  • Relaunching the project

    Alain Mauer09/01/2019 at 12:06 0 comments

    We still have the problem and now it's really time for this project. Even if it sounds not complicated, I had first to learn a little bit more about Arduino programming and to understand the fuse bits and boot-loader stuff.

    The Digitump Attiny has the fusebit set to lock the pin 5. This pin is needed for ISP programming. So I used this Instructable "Fuse Reset Attiny" to reset the fusebits with 12V. 

    After the reset , I could finally upload a 1Mhz Boolloader and I make the Digistump run on 3V

    Here my quick and dirty fuse bit reset'er.

View all 9 project logs

  • 1
    The Transmitter

    This is the transmission part of the UD-Alert

    It's based on an Attiny85 running at 1Mhz on his internal oscillator. A cheap 433Mhz RF module for the wireless transmission in the house,a end switch and a CR2032 battery.

    The circuit is in normal state in sleep mode, and use about 0.14uA. When the switch is activated, it generates an interrupt, and the Attiny is powering up the RF module over Pb3 and starts transmitting a code, with the help of the RCSwitch library, over Pb4. In this short moment, it pulls 0.7mA. I think on normal use, the battery should be good for 5-8 years. The RCSwitch library is for cheap power plugs, but it's exactly what I need for this project. The  modules i used can be found  here. 

    I can not tell you in meters, what distance they transmit, but it works through our house made of concrete over the 3 floors. 

  • 2
    The Receiver

    The receiver Part. You can add a display, but I think some kind of pager design will be more than enough.

    This part is under construction. for the moment, I use my Arduino QP project

View all instructions

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Ted Yapo wrote 04/06/2018 at 15:28 point

Hi Alain, this is a great project and I am looking forward to seeing how it works.  I especially like that you've stressed the safety aspects - lithium coin cells can be very dangerous around children, especially if they exhibit mouthing behaviors.

  Are you sure? yes | no

Alain Mauer wrote 09/07/2019 at 15:12 point

Hi, I just re-launched the project. For sure, I must guarantee that Scott can not access the battery. It will be impossible to change the CR2032 after, but for the few Euro in electronics and the time it will work, it will be a disposable part.

  Are you sure? yes | no

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