Advice for designing visual tool for autistic children (time device + leds) - Page 1
Forum section: electronics / beginners

author: JensAndree
author_rank: Contributor
timestamp: April 07, 2013, 02:14:02 pm
content: Hello dear tinkerers and electronics wizards!Both my sons are autistic and as all autistic children they have very little or no concept of time. In order to help them I got an aid a few years ago that shows the current time (15 min segments) with the aid of leds and a digital clock.These leds are mounted on both sides of a whiteboard where we can write, or put pictagrams, of what happens at that time.These "devices" are silly expensive ($1200+) and the need for a second one has emerged and I just can't afford to buy another one... (plus the fact that the electronics is really simple and I can build a better and more adapted myself)My oldest son has requested this new whiteboard to be mounted on the wall in his room so he can keep track of time whilst being on the computer so it doesn't have to cover 24 hrs.The plan is to have the leds cover 06:00 - 24:00 which should be 72 leds, but I might go for 24 hrs in order to not create a future problem...The size should also be somewhat smaller than it is today.I have plenty-a-leds at home but since I want to make this one a tad smaller I've decided to use smd leds. (actually I'm planning to use more or less only smd where possible since this is also a great project to learn new skills!)I will drive the whole thing with an atmega328p/32u or similar because I'm quite skilled with that microcontroller "family" and I've never used pic and STM's toolchain stinks IMHO)The left side of the board represents the "awake" hours and the right one "sleeping" hours. Every 15 minutes a light turns off which indicates the current time.When it's night all the right ones light up and starts to count down until morning. The night light have different colour than day.The one they have now have single colour leds (red for day and blue for night) but I'm thinking about using multi-coloured leds on this new one in order to highlight events on the board.I'd prefer not to connect the leds in a matrix so I've looked at both 74HC595 and MCP23017 as possible ways of addressing the leds. I've also looked at LPD8806 since that provides an excellent way of individually controlling each led (full colour and pwm).If I go down the LPD8806 route I could use all leds to signal alarms etc with patterns but it would add complexity to the design...The whiteboard we have today uses three Micrel MM5451YN display drivers so in order to not get accused for copying existing stuff I won't use themThe plan is to design "strips" of pcb's which contain perhaps 32 leds each which then are connected via wires in order to keep production costs down plus simplify maintenance if a board breaks down in the future. These strips will also enable many variants to be made. If this is the route then a simple arduino can control the whole lot but since I'm also adding a 4x7 segment display I might just as well design the controller board with both microcontroller and display.The solution should be driven by a generic wall-wart or similar.I will open source the files for others to build, or midify, since for some reason all resources for handicapped children are disgustingly expensive and very few actually can afford to buy them!I'm a beginner when it comes to electronic design but I have pretty good soldering skills and I'm a software engineer since 23 years back but the last few months I've learned Eagle cad enough to design simple but working pcb's.I have looked at using led strips that uses LPD8806 but the leds are too far apart in order to make it reasonable in size and by cutting each segment of a strip and placing them horisontally creates a soldering job that's vulgar... The strips are terrible to solder when cut...What choice(s) would you make if given the task to address 72, or 96 leds + driving the rest?It doesn't have to be low-cost but everything countsOther components that's required: RTC, battery backup, hidden buttons for setting the time, alarms etc.The plan is to mount the populated pcb's behind background paper and plexiglass in a frame. The paper will have a printed design and will be "easily" replaced if and when needed and the plexiglass is a cheap but working surface for non-stick whiteboard pens.( I wanted to change the numbers on the one we have today and the "kit" they sell with replacement stickers costed.... (drumroll)... $300 + VAT!!!)Here is a (promo) picture of the whiteboard they have today.I know it's not exactly a hard-core project with regards to the electronics and complexity of design but it's a great project for both me and the kids, and possibly for others?Many thanks in advance!p.s Did a search for LPD8806 on digi-key but scored zero... Does it have another name? Plenty on eBay though.

author: PetaVolt
author_rank: Contributor
timestamp: April 07, 2013, 04:33:24 pm
content: What is the target size for the whiteboard?Spencer

author: JensAndree
author_rank: Contributor
timestamp: April 07, 2013, 05:41:51 pm
content: Quote from: PetaVolt on April 07, 2013, 04:33:24 pmA3 (297 × 420 mm, 11.69 × 16.54 in) standing would be ideal but not critical.I need to fit 06:00 - 20:00 on the left side and 20:00 - 06:00 on the right. That should make it 56 + 40 leds.

author: Bloch
author_rank: Unknown
timestamp: April 07, 2013, 06:40:14 pm
content: Quote from: JensAndree on April 07, 2013, 02:14:02 pmFirst that are insane !About using a Cpu ....... well it almost begs to made of simple 74xxx counter and direct led driven.

author: Bloch
author_rank: Unknown
timestamp: April 07, 2013, 06:49:01 pm
content: That about buy a "standard" whiteboard (steel).And just use 3mm led and drill holes in the whiteboard ? and use wires to the led´s.

author: JensAndree
author_rank: Contributor
timestamp: April 07, 2013, 07:37:15 pm
content: Quote from: Bloch on April 07, 2013, 06:40:14 pmThe downside of that is that it becomes harder to "program".By adding visual feedback for certain "alarms", things like toilet visits etc, makes it easier for them to "keep track" of time and the feeling of self success.I have thought of adding a wireless network connection to the one we have now and syncing it with a calendar but that's taking a bit too far.I could use 5mm leds and drill through as you said but I'd really like to go for smd leds since I'd like to start working with smd. I'm also trying to keep the weight down a bit since the current one is rather heavy. Reliability is important so I'd prefer not to wire anything more than I have to.Autistic people really hates change and if an important tool like this malfunctions their whole day is down the toilet.I do appreciate all the suggestions though!It's perhaps hard for me to explain all the angles and requirements since I live with this 24/7 and is used to always be a few steps ahead and always make sure everything goes according to plan. I try to make them less depending of me, hence this new and improved tool.

author: MasterOfNone
author_rank: Regular Contributor
timestamp: April 07, 2013, 10:08:51 pm
content: Here’s some ideas1: Use Multiple bargraph LED drivers (LM314 etc) driven by multi-channel DACs connected to the MCU of your choice.Or2: Buy a Cheap LCD TV or Monitor (with a Visa Mount), buy a small cheap (and quiet ) computer like the Raspberry Pi ( around $30) . Write a some software that draws a bargraph on the left edge of the screen during the day or the right edge during the nigh. Buy a cheap thin magnetic white board and cut it to a size where it covers the centre of the screen leaving only the edges where the left and right bargraphs are drawn. Mount the White board on the front of the TV/Monitor (possibly hinged). Note the Raspberry Pi clock isn’t battery backed, but it can use internet via a Wifi dongle or the Ethernet I/F. (Also your electricity bill could go up with this idea).Or3: Forget the complex LED addressing schemes just use a different MCU to drive groups of LEDs. One MCU would be the Master and it would read the RTC (Note you can buy ready built RTC modules that connect to I2C, try Ebay or amazon). The other Slave MCUs would drive the LEDs. The Slave MCUs would only be connected to the Master via the serial port (RS232 type) . So the Tx-Data pin on Master would be connected to Rx-Data on all the Slaves (I.e. Multi-drop Simplex configuration). Therefore the Master can only send data, and the Slaves can only receive data.The Protocol:The Master sends: <ID>< LED Pattern>All slaves receive this message, but only the slave you have programmed to respond to <ID> sets the LEDs using <LED pattern>.OK, I never said they were good Ideas, I just said here's some ideas

author: akcoder
author_rank: Contributor
timestamp: April 08, 2013, 06:16:57 am
content: Quote from: Bloch on April 07, 2013, 06:40:14 pmWhile I agree that it is insanely expensive, you have to remember that the target market for these devices is rather small. If everyone had these in their house, it would run maybe $50 US. Think about when the first DVD players came out, they were many, many hundreds of dollars. Now, Wal-Mart sells them for $25-30.I don't know if these devices fall under FDA regulations, but if they do, that would be another reason for the high cost. The cost of complying with FDA regs, filing a 510k, documentation requirements, etc is a significant amount of money.All that said, I fully support Jens building one himself and open sourcing it! I'm a software guy by trade (which Jens has covered), otherwise I would be more than willing to help with this! I think its a fantastic project!-dan

author: akcoder
author_rank: Contributor
timestamp: April 08, 2013, 06:50:06 am
content: Quote from: JensAndree on April 07, 2013, 02:14:02 pmLook at the 74x165 or STP16C596. Those are the 16 bit big brother to the '595, which means less chips.Quote from: JensAndree on April 07, 2013, 02:14:02 pmSince your using the ATmega series of chips, you can pickup an "Arduino" RTC for next to nothing.Deal Extreme has one for $5, and this FleaBay one is $4eBay auction: #281012402441.To run in the event of a power failure, I'd use aLithium Ion/LiPoly charge controller like this one at SparkFun. It has a selectable output so you can enable and disable the charger via your microcontroller. Scratch that, thiscontroller gives you Li-Ion/LiPoly charge and boost to 5vin one board for $20.Good luck and keep us informed! I'm very interested, my wife has a nephew who is autistic and when he gets a little older something like this would help them immensely!BTW, have you seen the TED talk withAditi Shankardass?She is a neuroscientist who discovered (by accident) that a not insignificant percentage of children diagnosed with autism were actually having micro seizures. Her talk, along with the talks byDean Kamen(especially his "Luke Arm" talk, andAimee Mullinsare my favorites.-dan

author: Nickk2057
author_rank: Regular Contributor
timestamp: April 08, 2013, 08:28:13 am
content: Quote from: JensAndree on April 07, 2013, 02:14:02 pmi like to add to that as well....i am a autistic man myself and i made it through the years as well... meaning i use the passion of electronics for me to learn... and so i became a computer technician.. (which made me a great one at that with a slightly higher IQ as well)anyways... i hope you keep up the great work there... and POWER TO THE AUTISTICS!!!!!

author: amyk
author_rank: Super Contributor
timestamp: April 08, 2013, 11:07:19 am
content: Quote from: JensAndree on April 07, 2013, 07:37:15 pmThey need to be alarmed forthat?

author: JensAndree
author_rank: Contributor
timestamp: April 08, 2013, 11:58:06 am
content: Quote from: amyk on April 08, 2013, 11:07:19 amSadly yes. Unless toilet visits are scheduled they don't know when to go and it often ends in disaster... Not funny when it happens in school...Another common story is when autistic people grow up and move to own living, eating becomes an issue.I've met a guy who first didn't really know how much bread was needed for breakfast so in the morning he bought 14 loafs of bread - just to be sure.He then had breakfast at 07:00, a snack at 08:00, lunch at 09:00 and he'd already eaten his supper before 12:00! All because he was afraid to miss his meals...By providing enough help for my kids (7 and 9 years old) in order for them to do things at given times throughout the day they feel successful and able to perform most "basic" tasks as their friends do.I've developed quite a lot of software for my oldest sons Android phone which helps him to keep track of time. Most of them are available for free on Google Play, others are too crude for general release.I've had a talk with a hw engineer at work today and got some feedback but I still have a few things to work out before I start to order the components I lack and start prototyping, but I do have a addressable led strip at home with enough leds to do a breadboard version so I guess that's the next step.Thanks for all the comments so far! All the things I make which can be useful for someone else I will give away for free because these kids need all the help they can get.To be continued!

author: JensAndree
author_rank: Contributor
timestamp: April 08, 2013, 07:35:33 pm
content: Have just started to construct a crude prototype with WS2801 (instead of LPD8806) and SMD 5050 leds since I had a led strip with those components and although my Eagle skills are pretty basic I got something that seems to work and at a reasonable footprint.I found an I2C RTC in a box meant for Arduino so the clock is sorted.I also found a 4x7-segment I2C display to show the current time.This design is by far more complex than it need to be but on the other hand it's configurable in so many ways that it should suit everyone.When I showed my oldest son - who's requested this - that the leds can have any colour he liked the idea. Green for normal time and red for important stuff he said.He learned to change the current board himself two years ago and we progressed from only pictogram images to text only and if he's written the task himself then he can't cheatI think this will result in a win-win situation!One thing I noticed with Eagle cad tonight was that even if I add a SOP14 component, the routing grid stayed the same (50 mil) and autoroute resulted in massive FAIL... One could think that if you add tiny components and use autoroute it would change the grid to something compatible...?Hey, part of this exercise is to actually learn and evolve and not just make a copy-ish product!I've started to dread the soldering of those super-tiny resistors and caps already and I'm sure I'll destroy a few SOP14 drivers as well... Perhaps one should invest in a hot-air kit before attacking it?Back to drawing again...

author: JensAndree
author_rank: Contributor
timestamp: April 09, 2013, 07:20:55 pm
content: I've been prototyping a bit but spent most time in Eagle.I'm a total beginner in Eagle and so far it's been a journey of trial and error...(but I'm eager to learn although I still rely on autoroute - hence all the vias...)Can anyone have a look and see if it makes sense or if I'm way off and need to start over?I've attached the brd and sch for a 4 hour module + two screenshots that outlines the rough idea.Many thanks in advance!p.s I have no formal training in electrical engineering and only just started using Eagle but I'm happy to receive constructive criticism!

author: Rufus
author_rank: Super Contributor
timestamp: April 09, 2013, 07:38:15 pm
content: Quote from: JensAndree on April 09, 2013, 07:20:55 pmThe resistors are supposed to go in series with the FB pins not in series with the LEDs.

author: JensAndree
author_rank: Contributor
timestamp: April 09, 2013, 07:56:25 pm
content: Quote from: Rufus on April 09, 2013, 07:38:15 pmThanks!By looking at the datasheet I focused on the resistors that was in series with the LEDs but overlooked the others.Is this correct then? (please see attached picture)

author: Rufus
author_rank: Super Contributor
timestamp: April 09, 2013, 08:06:45 pm
content: Quote from: JensAndree on April 09, 2013, 07:56:25 pmI think so but only from my memory of looking at the data sheet yesterday.

author: JensAndree
author_rank: Contributor
timestamp: April 09, 2013, 09:09:09 pm
content: Quote from: Rufus on April 09, 2013, 08:06:45 pmMany thanks!

author: JensAndree
author_rank: Contributor
timestamp: April 15, 2013, 08:07:00 am
content: Just thought I'd make an update since I've asked a few questions and got help.I've made a working prototype with ws2801 and it does what it says on the box. However, in order to make this available for "anyone" at low-cost my smd pcb is perhaps the wrong direction to take so I'm redesigning the whole concept to be built only from already available components and will try to keep soldering to a minimum and no custom pcb's.I will construct a first prototype based on an Arduino Leonardo and a ws2801 based led strip (cut into 4 segments) and a byb rtc.I will also add an i2c enabled 4x7-segment display for the digital clock readout.As soon as the new prototype is done I shall post it here for criticism and feedback before making BOM, code and instructions available.There will always be other projects where I can practice smd soldering

author: Unknown
author_rank: Unknown
timestamp: May 16, 2013, 03:57:03 pm
content: Hi, just wondered did you manage to get time to put something together?