simplesi
Posts: 2327
Joined: Fri Feb 24, 2012 6:19 pm
Location: Euxton, Lancashire, UK
Contact: Website

Please design a Primary School Board

Sat Aug 18, 2012 9:45 pm

I'm looking for some to design a GPIO expansion board - 8 digital outputs/4inputs, 2 motor outputs and 4 analogue inputs for use in primary schools.

This amount of i/o should allow for a decent range of projects for primary school children to program with via Scratch.

My idea to get i produced (if it would make things cheaper) would be to just get circuit boards produced and then bundle them into a bag with the components needed and get local effort to each school to have a solder fest evening with some pupils and get them built.

But I need a good circuit design that would be medium bullet proof-eg. cope with outputs being mistaken for inputs and either held high at 5V or shorted to ground etc :)

Anyone know some electronics :)

Cheap component count would be welcome :)

Simon
Seeking help with Scratch and I/O stuff for Primary age children
http://cymplecy.wordpress.com/ @cymplecy on twitter

User avatar
Jim JKla
Posts: 2218
Joined: Sun Jan 29, 2012 11:15 pm
Location: Newcastle upon Tyne UK

Re: Please design a Primary School Board

Sun Aug 19, 2012 6:46 am

Wow! so nothing complex then :D

You are probably right the nearest we have at this time is this http://elinux.org/RPi_Screw_Connector_Breakout_Board

I suspect this is a a little more complex than you expect with less functionality.

It is early days lets face it the educational RPi is still in the wings and from your post I suspect the Gert Board is probably what you need and it is out as kit form and it's not a cheap option. ;)
Noob is not derogatory the noob is just the lower end of the noob--geek spectrum being a noob is just your first step towards being an uber-geek ;)

If you find a solution please post it in the wiki the forum dies too quick

jamesh
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 26864
Joined: Sat Jul 30, 2011 7:41 pm

Re: Please design a Primary School Board

Sun Aug 19, 2012 7:17 am

To OP - what is you cost requirements? I know 'as cheap as possible', but what figure are you thinking about?
Principal Software Engineer at Raspberry Pi (Trading) Ltd.
Contrary to popular belief, humorous signatures are allowed.
I've been saying "Mucho" to my Spanish friend a lot more lately. It means a lot to him.

simplesi
Posts: 2327
Joined: Fri Feb 24, 2012 6:19 pm
Location: Euxton, Lancashire, UK
Contact: Website

Re: Please design a Primary School Board

Sun Aug 19, 2012 10:31 am

To OP - what is you cost requirements? I know 'as cheap as possible', but what figure are you thinking about?
My target price would be £10 (Ex Vat as schools don't pay VAT) (In large say 25% of schools in the country buy 10 of them type quatities)

I don't mind paying $25 to trailblaze them :)

What we need is at least a reference design and then we can all work out how to do it cheaper as its MUCH easier to be a critic/commentator than a creator :)

Simon
Seeking help with Scratch and I/O stuff for Primary age children
http://cymplecy.wordpress.com/ @cymplecy on twitter

tech_monkey
Posts: 130
Joined: Fri Mar 09, 2012 6:12 pm

Re: Please design a Primary School Board

Sun Aug 19, 2012 11:00 am

Maybe a Gert board Lite version.
Does your school have A level students, maybe a project for them would be to design this board. Or talk to your local technical college, they are always wanting project ideas for their students.
http://www.casatech.eu

simplesi
Posts: 2327
Joined: Fri Feb 24, 2012 6:19 pm
Location: Euxton, Lancashire, UK
Contact: Website

Re: Please design a Primary School Board

Sun Aug 19, 2012 11:24 am

Maybe a Gert board Lite version.
Could you put together a circuit for us please :)
Does your school have A level student
"Please Design a Primary School Board" - we don't have many A-Level candidates in primary schools :)

Simon
Seeking help with Scratch and I/O stuff for Primary age children
http://cymplecy.wordpress.com/ @cymplecy on twitter

techpaul
Posts: 1512
Joined: Sat Jul 14, 2012 6:40 pm
Location: Reading, UK
Contact: Website

Re: Please design a Primary School Board

Sun Aug 19, 2012 12:31 pm

What sort of connections are you expecting to use for the I/O?

Easiest safety method is to use DIFFERENT connectors for motors, analogue, inputs and outputs.

Warning with this much I/O one of the major costs will be the price of the connectors. I would expect that of your £10 target price even with ZERO profit the connectors will be £5 of the cost in volumes less than 1000.

Also to fit that many I/O on and be useable by Primary School children the connectors will need spacing out and easy connection methods (spring release of push levers), so the board will be larger pushing up PCB costs.
Just another techie on the net - For GPIO boards see http:///www.facebook.com/pcservicesreading
or http://www.pcserviceselectronics.co.uk/pi/

techpaul
Posts: 1512
Joined: Sat Jul 14, 2012 6:40 pm
Location: Reading, UK
Contact: Website

Re: Please design a Primary School Board

Sun Aug 19, 2012 12:50 pm

Alternative solution for you

Start with base board on I2C with PCF8575 (16 bit input or output) and Analogue inputs (only slow moving limited to 0-5V) using a PCF8591. I already have a board with PCF8575 on adding PCF8951 would be easy.

Have an I2C daisy chain connector to talk to add in boards for

Motor control (with its own power supply or batteries)

This way some of the connector issues are reduced as they only use the motor board when needed.
I think more teachers could view motor control as an addon as that is all sorts of other complicatiuons, electrical, mechanical, physical and environmental as how to do it, is there room for something motorised or several motorised units moving about. It may transpire they have only one motor unit.

For possibilities some boards are shown as safer breakout boards on http://www.facebook.com/pcservicesreading
Just another techie on the net - For GPIO boards see http:///www.facebook.com/pcservicesreading
or http://www.pcserviceselectronics.co.uk/pi/

simplesi
Posts: 2327
Joined: Fri Feb 24, 2012 6:19 pm
Location: Euxton, Lancashire, UK
Contact: Website

Re: Please design a Primary School Board

Sun Aug 19, 2012 12:53 pm

The cost of the connectors is irrelevant if I don't have a circuit to connect them to :)
BUT ... :)
What sort of connections are you expecting to use for the I/O?
Plan A - 4mm banana (as a lot of exisiting DT/Control stuff in schools uses it, Plan B - LoudSpeaker type - e.g push wire in - its got safety issues but then again fingers are for burning in the word of the great philospher Marco-Pierre White :) - Plan C Something else :)
Easiest safety method is to use DIFFERENT connectors for motors, analogue, inputs and outputs.
Useful idea :)
Warning with this much I/O one of the major costs will be the price of the connectors.
So we are going to need cheap ones - when I was liitle - I once saw main terminal blocks used as cheap connectors :)
Also to fit that many I/O on and be useable by Primary School children the connectors will need spacing out
The connectors are going on lid/sides of the case box, the case can be tall enough to cope - but it will be same width height as RPi case (so its looks nice for the teachers :) )

One idea for the case is to ask the pibow people to make an extended one incorporating the RPi and the PriBoard but lets see what the circuit board comes out like first :)

WHAT I NEED IS A CIRCUIT PLEASE :)

Simon
Seeking help with Scratch and I/O stuff for Primary age children
http://cymplecy.wordpress.com/ @cymplecy on twitter

simplesi
Posts: 2327
Joined: Fri Feb 24, 2012 6:19 pm
Location: Euxton, Lancashire, UK
Contact: Website

Re: Please design a Primary School Board

Sun Aug 19, 2012 1:00 pm

Alternative solution for you...
Got a circuit? :)

We COULD get away with just digital i/o for very simple but that's really a KS1 (4-7 age) device - I'm targeting 7-11 (and possibly KS3 up to age 13) who want to build something with motors and analogue sensors.

But having said that - a modular approach could be the way but I say - lets get a design that does it all and see where we are at then :)

regards
Simon
Seeking help with Scratch and I/O stuff for Primary age children
http://cymplecy.wordpress.com/ @cymplecy on twitter

techpaul
Posts: 1512
Joined: Sat Jul 14, 2012 6:40 pm
Location: Reading, UK
Contact: Website

Re: Please design a Primary School Board

Sun Aug 19, 2012 1:10 pm

simplesi wrote:The cost of the connectors is irrelevant if I don't have a circuit to connect them to :)
BUT ... :)
What sort of connections are you expecting to use for the I/O?
Plan A - 4mm banana (as a lot of exisiting DT/Control stuff in schools uses it, Plan B - LoudSpeaker type - e.g push wire in - its got safety issues but then again fingers are for burning in the word of the great philospher Marco-Pierre White :) - Plan C Something else :)
For that many I/O requires a large area to mount them on, and 4mm or loudspeaker connectors are only cheap in 10000+. Also unless PCB mounted the costs are astronomical for someone to wire them up inside.
Warning with this much I/O one of the major costs will be the price of the connectors.
So we are going to need cheap ones - when I was liitle - I once saw main terminal blocks used as cheap connectors :)
These require screwdrivers for most and it is NOT so easy to make types they cannot mis-wire.
Some are available with push levers for easy wiring but cost more.
Also to fit that many I/O on and be useable by Primary School children the connectors will need spacing out
The connectors are going on lid/sides of the case box, the case can be tall enough to cope - but it will be same width height as RPi case (so its looks nice for the teachers :) )
Try getting lots of 4mm connectors together 8 output and 4 input with at least 2 ground, plus 4 analog with a gnd EACH and two motors with GND each is a LARGE area !!
One idea for the case is to ask the pibow people to make an extended one incorporating the RPi and the PriBoard but lets see what the circuit board comes out like first :)

WHAT I NEED IS A CIRCUIT PLEASE :)

Simon
What you need is to think again it ONLY stands chance of being feasible as a modular approach. The costs of connectors and any hand wiring to 4mm connectors means it will be £100+ ion volumes of 500+ BEFORE anybody makes any profit or ships or supports it or writes documentation.

The electronics is EASY the physical and mechanical are not possible even at £25 unless everybody works for free and has no mortgages to pay or need to eat
Just another techie on the net - For GPIO boards see http:///www.facebook.com/pcservicesreading
or http://www.pcserviceselectronics.co.uk/pi/

simplesi
Posts: 2327
Joined: Fri Feb 24, 2012 6:19 pm
Location: Euxton, Lancashire, UK
Contact: Website

Re: Please design a Primary School Board

Sun Aug 19, 2012 1:24 pm

The electronics is EASY
:) and .... :)

I understand your points with the connectors but without a circuit to connect them too, its a moot point at this time :)

Maybe we'll end up using drawing board pins and paper clips like we normal do in primary schools :)

There is an existing device with a slightly large footprint that has the type/number of connectors on it and by shifting shome to the sides, Ithink the physical arrangement is quite possible - and kids have small hands so they can work better in confined spaces :)
The costs of connectors and any hand wiring to 4mm connectors means it will be £100+ ion volumes of 500+ BEFORE anybody makes any profit or ships or supports it or writes documentation.
Well the maximum price is £99 because thats what the current commercially made device costs and that comes with manuals, psu, sensors etc etc :)

I think you missed the bit about - lets get a circuit :) then we'll get a PCB desigined and then price up board + bits and send them out to schools in a bag (a la Gertboard) and get local geek hero's/parents/high school tech students to wire them up (as we are all in the teach a man to fish program here :) )

Simon
PS Did I mention that I need a circuit? :)
Seeking help with Scratch and I/O stuff for Primary age children
http://cymplecy.wordpress.com/ @cymplecy on twitter

simplesi
Posts: 2327
Joined: Fri Feb 24, 2012 6:19 pm
Location: Euxton, Lancashire, UK
Contact: Website

Re: Please design a Primary School Board

Sun Aug 19, 2012 1:27 pm

PS for the avoidance of doubt - I could design one myself but it would probably end up electrocuting the pupils and blowing up the main incoming fuse to a school so you REALLY don't want me doing this - think of the the kids :)

Simon
Seeking help with Scratch and I/O stuff for Primary age children
http://cymplecy.wordpress.com/ @cymplecy on twitter

techpaul
Posts: 1512
Joined: Sat Jul 14, 2012 6:40 pm
Location: Reading, UK
Contact: Website

Re: Please design a Primary School Board

Sun Aug 19, 2012 1:41 pm

Wait a couple of days and I should have time to get the PCF8575 board tested the circuit is simple and I2C, add PCF8591 is easy (done that many times). The layout connector types and positioning is important to get right.

Motor control should be a seperate module and requires more circuitry and power source. Power source needs yet another connector even if battery pack, if battery pack on PCB that makes PCB larger. This WILL make it larger than footprint of the Pi.

I suggest you mock up the connector layout and battery pack to see what size it actually is.

PCB turnaround times without paying premiums and doing a layout from scratch is 2-3 weeks than a day to assemble to test. Wiring up those connectors and mounting them on something is half a day to a day depending on the experience of the assembler and a pre-drilled plate to mount them on. That is for each unit. The pre-drilled plate has to be designed and built by someone then LABELLED.

One thing these days everybody who makes electronics does is reduce the amount of wires between boards and to connectors, because labour is expensive even in China, if the board can just be auto-assembled in one go it is easier.

If each school wants 10 you either have somebody who has 1 -2 weeks of spare time to make the connector wiring for you or 10 people suitable skilled to do it and then test they have done it right.

I have been involved in electronics manufacturing and varioous parts of it from design to assembly line for over 30 years and know you are at present reaching beyond your means. For a general product for all schools it has to be well designed BEFORE the first PCB and mechanical assembly and will need probably two iterations to get right and produce manuals etc. Include all the drawings and wiring instructions.
Last edited by techpaul on Sun Aug 19, 2012 1:44 pm, edited 1 time in total.
Just another techie on the net - For GPIO boards see http:///www.facebook.com/pcservicesreading
or http://www.pcserviceselectronics.co.uk/pi/

techpaul
Posts: 1512
Joined: Sat Jul 14, 2012 6:40 pm
Location: Reading, UK
Contact: Website

Re: Please design a Primary School Board

Sun Aug 19, 2012 1:42 pm

PS forgot to mention I am now off to a customer site to sort out some servers, networks etc so probably wont be around for a few days.
Just another techie on the net - For GPIO boards see http:///www.facebook.com/pcservicesreading
or http://www.pcserviceselectronics.co.uk/pi/

jamesh
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 26864
Joined: Sat Jul 30, 2011 7:41 pm

Re: Please design a Primary School Board

Sun Aug 19, 2012 1:53 pm

simplesi wrote:
The electronics is EASY
:) and .... :)

I understand your points with the connectors but without a circuit to connect them too, its a moot point at this time :)

Maybe we'll end up using drawing board pins and paper clips like we normal do in primary schools :)

There is an existing device with a slightly large footprint that has the type/number of connectors on it and by shifting shome to the sides, Ithink the physical arrangement is quite possible - and kids have small hands so they can work better in confined spaces :)
The costs of connectors and any hand wiring to 4mm connectors means it will be £100+ ion volumes of 500+ BEFORE anybody makes any profit or ships or supports it or writes documentation.
Well the maximum price is £99 because thats what the current commercially made device costs and that comes with manuals, psu, sensors etc etc :)

I think you missed the bit about - lets get a circuit :) then we'll get a PCB desigined and then price up board + bits and send them out to schools in a bag (a la Gertboard) and get local geek hero's/parents/high school tech students to wire them up (as we are all in the teach a man to fish program here :) )

Simon
PS Did I mention that I need a circuit? :)
Well, if you calm down and chill out a bit, and stop being so impatient, perhaps someone might have the time to spend a day or two (of their own time) knocking one up. This stuff doesn't happen instantly. We get it - you want some time donated to do some work. No need to keep on about it.

Note that the cost of components is going to be high (connectors as mentioned).

The Gertboard does all you need and more, and the circuits for that are available - a mod of those to cut off unnecessary stuff might be a good start.
Principal Software Engineer at Raspberry Pi (Trading) Ltd.
Contrary to popular belief, humorous signatures are allowed.
I've been saying "Mucho" to my Spanish friend a lot more lately. It means a lot to him.

simplesi
Posts: 2327
Joined: Fri Feb 24, 2012 6:19 pm
Location: Euxton, Lancashire, UK
Contact: Website

Re: Please design a Primary School Board

Sun Aug 19, 2012 2:34 pm

Well, if you calm down and chill out a bit, and stop being so impatient, perhaps someone might have the time to spend a day or two (of their own time) knocking one up. This stuff doesn't happen instantly. We get it - you want some time donated to do some work. No need to keep on about it.
The point about impatience is well understood but I am an impatient person - sorry :(
(Target for prototype - 2 weeks on Tues -start of school year :) )

Boards in production, me retiring on 1% cut on all sales (Joke :) ) - ready for 2nd half Autumn Term with full lesson plans - activities/ideas for a medium D&T/IT bright primary teacher :)

I believe I was just trying to keep the thread on that thing that you don't want me to mention again :)

techpaul was making some valid points over the whole project feasibility and I was trying to bring it back to the "its the circuit design" thread purpose :)
The Gertboard does all you need and more
I actually don't think it does :( - It does a lot of stuff but not whats required (Just 1 motor O/P for instance) - unless I've mis-read the docs which is entirely possible

AFAIK The Gertboard is a secondary school and greater type device - to be useful as an I/O board and also to encourage people to think about things and soldering etc.

I just want a working simpler, cheaper board and I think if someone sticks a circuit up to do it, then the community could/would hopefully pile on and suggest better/cheaper/smaller ways of achieving the same end.

I feel like a prophet without honour at the moment but SOMEONE has got to get the RPi down to Primary Level D&T and it looks like its me at the moment -until the big/clever boys and girls decide to come along and show me up - I look forward to this day :)
Seeking help with Scratch and I/O stuff for Primary age children
http://cymplecy.wordpress.com/ @cymplecy on twitter

User avatar
croston
Posts: 711
Joined: Sat Nov 26, 2011 12:33 pm
Location: Blackpool
Contact: Website

Re: Please design a Primary School Board

Sun Aug 19, 2012 2:44 pm

I think this Raspberry Jam may be of interest to you as it may well be concentrating on exactly what you are after:
http://www.raspberrypi.org/phpBB3/viewt ... 57&t=14636

tech_monkey
Posts: 130
Joined: Fri Mar 09, 2012 6:12 pm

Re: Please design a Primary School Board

Sun Aug 19, 2012 2:54 pm

Can't see why you can't say start with a gert board and then go from there. Since this would give you some idea of what the kids are capable of doing and if you really need anything different.
Also you obviously didn't read my last post completely, as I said "Does your school have A level students, maybe a project for them would be to design this board. Or talk to your local technical college, they are always wanting project ideas for their students."
Meaning if you have access to A level students get them to design and build a board for you. Not use some thing designed for A level students.

Still think the local Technical college might be your best bet. They might even all ready have something similar you could look at. Just pick up the phone and ask them.
http://www.casatech.eu

techpaul
Posts: 1512
Joined: Sat Jul 14, 2012 6:40 pm
Location: Reading, UK
Contact: Website

Re: Please design a Primary School Board

Sun Aug 19, 2012 2:56 pm

simplesi wrote:I believe I was just trying to keep the thread on that thing that you don't want me to mention again :)

techpaul was making some valid points over the whole project feasibility and I was trying to bring it back to the "its the circuit design" thread purpose :)
A good circuit design is no good without a GOOD specification and limits of design set first.

Anybody can create a circuit, but every time you have to respin add a month into the timeline for PCB and documentation and software, even if we were not doing this in our spare time!
I just want a working simpler, cheaper board and I think if someone sticks a circuit up to do it, then the community could/would hopefully pile on and suggest better/cheaper/smaller ways of achieving the same end.
Yes they might but more likely to act like a committe going nowhere and making several incompatible versions, all based on their needs not the general need.
I feel like a prophet without honour at the moment but SOMEONE has got to get the RPi down to Primary Level D&T and it looks like its me at the moment -until the big/clever boys and girls decide to come along and show me up - I look forward to this day :)
The big boys will do it by putting a team on it and getting the GOOD specification first, before looking at a circuit, which is something I am sure you are familiar with in D&T work out what you want, then do the drawings, then make it and document it.

Round here I am one of the few who has actual experience of electronics, software, projects, ICT and computing in schools as I have it daily from the other half who is ICT and Computing teacher for 11-18 year olds. having done projects with kids, given talks, design and built teaching aids. Also looked over projects, the syllabus and exam questions.

So bear in mind I do understand your level of syllabus better than most and a lot of the other issues.

One teaching aid we considered making into a sellable product but the cost of connectors and cables to achieve it made it too expensive unless we could build 100,000 in one batch, which is a lot of funding in hope that we could move them let alone where do we store them, until sold, arranging shipping etc...
Just another techie on the net - For GPIO boards see http:///www.facebook.com/pcservicesreading
or http://www.pcserviceselectronics.co.uk/pi/

simplesi
Posts: 2327
Joined: Fri Feb 24, 2012 6:19 pm
Location: Euxton, Lancashire, UK
Contact: Website

Re: Please design a Primary School Board

Sun Aug 19, 2012 3:25 pm

Forums - love em - hate em - can't do without em :)
PM sent to techpaul and tech_monkey to calm the waters :)

"I'm looking for some to design a GPIO expansion board - 8 digital outputs/4inputs, 2 motor outputs and 4 analogue inputs for use in primary schools." :)

I just would like a good stab at this to start with - no PCB layout needed - just a nice little circuit diagram that would/could/might do the job. :)

.

Can you help? :)

Simon
PS If there is a mod around - if you could copy all the posts to another thread but leave this thread alone (as its hyperlinked on the rest of T'internet and just leave the writing above as the 1st post - that would be handy to restart things off again :)
Seeking help with Scratch and I/O stuff for Primary age children
http://cymplecy.wordpress.com/ @cymplecy on twitter

User avatar
DexOS
Posts: 876
Joined: Wed May 16, 2012 6:32 pm
Contact: Website

Re: Please design a Primary School Board

Sun Aug 19, 2012 3:40 pm

You need to design something like "littlebits" but for the R PI
http://littlebits.cc/

They are open hardware so you should not have a problem there
https://github.com/littlebitselectronics/eagle-files
Batteries not included, Some assembly required.

simplesi
Posts: 2327
Joined: Fri Feb 24, 2012 6:19 pm
Location: Euxton, Lancashire, UK
Contact: Website

Re: Please design a Primary School Board

Sun Aug 19, 2012 3:47 pm

You need to design
Stop there - I'm looking for someone else to do the work :)

Very nice piece of kit - It could be very interesting to hook some of it upto a RaspberryPI through a little add on circuit board :)

Simon
Seeking help with Scratch and I/O stuff for Primary age children
http://cymplecy.wordpress.com/ @cymplecy on twitter

User avatar
DexOS
Posts: 876
Joined: Wed May 16, 2012 6:32 pm
Contact: Website

Re: Please design a Primary School Board

Sun Aug 19, 2012 3:53 pm

simplesi wrote:
You need to design
Stop there - I'm looking for someone else to do the work :)

Very nice piece of kit - It could be very interesting to hook some of it upto a RaspberryPI through a little add on circuit board :)

Simon
They are already designed and eagle files available.
You need to find someone to design a R PI interface board ;) .
Batteries not included, Some assembly required.

simplesi
Posts: 2327
Joined: Fri Feb 24, 2012 6:19 pm
Location: Euxton, Lancashire, UK
Contact: Website

Re: Please design a Primary School Board

Sun Aug 19, 2012 4:17 pm

You need to find someone to design a R PI interface board
Do you know anyone who could and would design an RPi interface board? :)
Simon
Seeking help with Scratch and I/O stuff for Primary age children
http://cymplecy.wordpress.com/ @cymplecy on twitter

Return to “HATs and other add-ons”