Pi-Face IO board for Raspberry Pi

[Alec Clews]

I've been put in touch with someone in Sydney who is distributing the Pi-Face IO board

See http://pi.cs.man.ac.uk/interface.htm

"Pi-Face Digital is the first of a range of interfaces to allow the Raspberry Pi to control and manipulate the real world. It allows the Raspberry Pi to read switches connected to it – a door sensor or pressure pad perhaps, a microswitch or reed switch, or a hand held button. With appropriate easy to write code, the Raspberry Pi then drives outputs, powering motors, actuator, LEDs, light bulbs or anything you can imagine to respond to the inputs."

Who is interested?

NB -- This is all being done at cost by everyone involved and is not a commercial venture.

I'm guessing the cost would be around $50-$70 (I'm totally guessing based on GBP30 cost in UK) but the price is being worked out.

I just need approx numbers for now. No commitment yet.

However once we do commit then it's firm. I can't afford to purchase unwanted boards.

Cheers

Alec

[Jacob Gillies]

Looks good but $50-70 for a handful of Terminals and couple of relays and buffers is steep. 

I suppose the PCB is nice and for those with plenty of cash it might be a good solution.

Alec

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[Andy Gelme]

hi All,

On 2012-08-6 09:31 , Jacob Gillies wrote:
> Looks good but $50-70 for a handful of Terminals and couple of relays
> and buffers is steep.

You need to count all the costs, for a low-volume production run, before
you make a true comparison ...

- Professional PCB manufacture
- 9 terminal blocks
- 2 relays
- I/O expander/buffer chip
- Hardware assembly time
- Developing (perhaps), modifying / patching (definitely) an SPI kernel
driver
- Developing example code
- Support

... plus a bunch of miscellaneous costs ... and some modest
consideration for the time/effort that the designers have put into
making this happen.

It's important to realize that community efforts (or even in the case of
University of Manchester Comp Sci) are often labours-of-love that don't
make a bunch of money for the people driving the project / product.

However in time, either Pi-Face or some other effort will ramp up to
serious quantities and you'll start to see more large-scale commercially
competitive prices.

> I suppose the PCB is nice and for those with plenty of cash it might
> be a good solution.

Only a small percentage of people have the skills to produce such a
board and the associated firmware by themselves.

So, the problem is really about choice ... and providing hackers with
different options, depending upon their particular skills, time
availability and financial situation.

Some hackers have all the skills required and can make something for
just a few dollars, with existing parts lying around their fully
kitted-out work desk and value their time at $0 / hour (as a hobby that
is fine). Those hackers have a choice.

Hopefully, with the monthly Saturday Raspberry Jam sessions and the
HackerSpace meetings in general, we'll be able to help more people be
self-sufficient ... or at least tackle these projects within the context
of the HackerSpace (and not have to buy everything off the shelf).

- - - - - - - - - - - - - - - -

Members of our HackerSpace have developed a number of Arduino shields or
custom Arduino boards, which have been the basis for Linux Conference
Australia Arduino mini-conferences, competitions, internal projects, etc.

Some of those people are already thinking about Raspberry Pi add-on boards.

If we ask nicely (they are very busy), they may come out and chat about
their formative ideas ... and we could potentially pull together a
custom CCHS (Melbourne HackerSpace) development board, perhaps as part
of the monthly Saturday Raspberry Jam sessions.

It'll be a matter of prioritizing some of the projects already underway,
which includes LCA2013 Arduino mini-conference, 3D printer boards, laser
cutter electronics, Mr. Bones ... other group and individual projects.

Based on past experience, the base-line cost for any board we do will be
$50 or (likely) more. However, it'll probably do a *lot more* than the
Pi-Face.

Should such a project get off the ground, then the main result will not
be a cheap board (if you count up all the time and cost) ... although,
it would be reasonable value for money. The main result would be that
the people involved, which can be any HackerSpace members, would learn a
considerable amount of new and interesting things / skills.

- - - - - - - - - - - - - - - -

Is there any interest in designing / producing our own Raspberry Pi
add-on board ?

Does anyone have suggestions for what sort of functionality they would
like to see on that board ?

Is there someone who is willing to lead the effort ?

Note: The project leader doesn't have to be the one designing the actual
board, it can be someone who is willing to manage the effort, bring
together the members and generally look after the health / timely delivery.

--
-O- cheers = /\ /\/ /) `/ =
--O -- http://www.geekscape.org --
OOO -- an...@geekscape.org -- http://twitter.com/geekscape --

[David Lyon]

One way to achieve something similar may be to use this
chip:

 - http://au.element14.com/microchip/mcp23008-e-p/ic-io-expander-8bit-i2c-pdip18/dp/1439387

and do something like this:

 - http://embedded-lab.com/blog/?p=2834

[Andy Gelme]

hi All,

On 2012-08-6 09:42 , David Lyon wrote:
> and do something like this:
> - http://embedded-lab.com/blog/?p=2834

Take care ... that is a 5 VDC circuit (no problem for a PIC12F683) and
your Raspberry Pi operates at 3.3 VDC.

You would need to make appropriate adjustments (run at a lower voltage,
alter some resistor values) to ensure that you don't damage your
Raspberry Pi.

The MCP23008 looks like it operates with voltages as low as 1.8 VDC.

[tubular]

On Monday, 6 August 2012 10:42:21 UTC+10, andyg (@geekscape) wrote:

Is there any interest in designing / producing our own Raspberry Pi 
add-on board ? 

Does anyone have suggestions for what sort of functionality they would 
like to see on that board ? 

Is there someone who is willing to lead the effort ? 

I'm happy to lead an initial CCHS effort into a variant of the Pi Face, based on a previous design

http://forums.parallax.com/showthread.php?136266-Sneak-Peek-PP-Low-Cost-Industrial

My proposal for a Pi variant would be 

- Pi would connect "cpu down / SD card up" to connect to the base PCB, which would have terminals, relays, PSU onboard 

- Use the 36 pin Bud Enclosure (available from Altronics) - its about 100mm wide, SD card and USB from the Pi would stick out for easy access

- Use the Adafruit 2.0" TV which should fit nicely into the case and be visible through the transparent lid

- Use slimline Altronics relays, din rail case, screw terminals etc (single source, perhaps we can even persuade them to kit them up) 

- 3D print a custom lid for the bud enclosures, with holes in the right places for the Pi 

I would need help on the software side of the Pi, as its mostly new to me.   Big thanks to Alec for the image from Saturday, to get me started.  

I hope to be in tonight, I'll bring some prototypes.   It should be easy enough to hook up the pi to the existing board which has fets, optos, psu already in place.  

cheers

Lachlan

[Peter Rogers]

I am interested in looking into making our own pcb,

 

And as it turns out i have some of the mcp30s08 chips mentioned in the i/o expander article.

 

I was thinking about some basic i/o, power supply and maybe some led’s/switches for learning i/o.

 

Possibly also adding some sort of display as one thing we found on the weekend is its hard to know which board is yours when theres 5 others on the same network.

 

Anyway. Im looking into it so im happy to help

 

Peter

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[Michael Borthwick]

On 06/08/2012, at 3:00 PM, tubular wrote:

> - Use the 36 pin Bud Enclosure (available from Altronics) - its
> about 100mm wide, SD card and USB from the Pi would stick out for
> easy access

Can you please provide a link?
I can't find anything called a Bud Enclosure on the Altronics site.

[tubular]

Can you please provide a link?
I can't find anything called a Bud Enclosure on the Altronics site.

Hi Michael 

Bud page here 

http://www.budind.com/view/Plastic+Boxes/DIN+Rail+Mount+Multi-Board+Box 

Altronics parts

H8456 - "6 module" is about 100mm wide is the one I'm thinking for the Pi 

[Luke Weston]

Ultimately you want to determine what you actually want the interfaces and inputs and outputs to and from the outside world to actually be, and once you've got that layer specified you can then specify the lower-level stuff like what ICs you're going to use.

[Luke Weston]

If you're designing a project and having a number boards made and sourcing components and assembling the boards in-house, sourcing the components from one of the Australian retail shopfront suppliers like Altronics or Jaycar is probably one of the worst possible choices, in terms of very high costs and limited range to choose from. Somewhere like Digi-Key would be far better and cheaper.

[tubular]

On Tuesday, 7 August 2012 00:09:59 UTC+10, Luke Weston wrote:

If you're designing a project and having a number boards made and sourcing components and assembling the boards in-house, sourcing the components from one of the Australian retail shopfront suppliers like Altronics or Jaycar is probably one of the worst possible choices, in terms of very high costs and limited range to choose from. Somewhere like Digi-Key would be far better and cheaper.

Hi Luke

I agree Digikey is better and cheaper, but I'm not convinced we have to go down that path to come up with something useful here.    I guess I'm imagining a general purpose 'starter' design with a few of each type of basic i/o, it could easily be extended or modified with version 2.  

I can't make it to CCHS tonight, unfortunately, but if you're there let's find out what others would find useful with regard to I/O, and I2C / SPI peripherals, and also what physical form would work.  The lack of mounting holes makes the latter a good chunk of the challenge

[David Lyon]

It's not that Australian retailers are greedy. They just
have higher costs and smaller markets.

Is this the connector?

 - http://au.element14.com/te-connectivity-amp/102387-6/connector-housing-female/dp/1654576?Ntt=2.54mm+26+way+female

Something like it in china is less. This is for cable connect:

 - http://www.aliexpress.com/wholesale?SearchText=26+pin+female

In tokyo, it's about 60c:

 - http://akizukidenshi.com/catalog/g/gC-00084/

[David Lyon]

There was an interesting article about this posted on hackaday recently:

 - http://hackaday.com/2012/08/05/not-quite-building-a-raspi-arduino-bridge/

[David Lyon]

On Mon, Aug 6, 2012 at 10:56 AM, Andy Gelme <an...@geekscape.org> wrote:

Take care ... that is a 5 VDC circuit (no problem for a PIC12F683) and
your Raspberry Pi operates at 3.3 VDC.

I see your point.

Noticed this chip at Element14, which falls under the magic $1 each
(if 20 are bought):

 - http://au.element14.com/texas-instruments/pcf8574apwr/ic-8-bit-expander/dp/1408304

It's suitable for 3.3v operation.

[Clifford Heath]

On 06/08/2012, at 8:16 AM, Alec Clews wrote:
> I've been put in touch with someone in Sydney who is distributing the Pi-Face IO board
> See http://pi.cs.man.ac.uk/interface.htm

I put up a question on the blog post about the maximum SPI clock rate,
but got no answer.

The screen-shots show only 40KHz being used, which would put a serious
crimp in the resultant bit-toggle rate. I assume the RPI can go a lot faster
than that - the chip on Piface supports up to 20MHz.

Anyone know?

Clifford Heath.

[Luke Weston]

Is this the connector?

 - http://au.element14.com/te-connectivity-amp/102387-6/connector-housing-female/dp/1654576?Ntt=2.54mm+26+way+female

Something like it in china is less. This is for cable connect:

 - http://www.aliexpress.com/wholesale?SearchText=26+pin+female

In tokyo, it's about 60c:

 - http://akizukidenshi.com/catalog/g/gC-00084/

Assuming what you want is a 26-pin (2x13) 0.1" IDC ribbon cable plug with strain relief, the Digi-Key HSR26S-ND is 34 cents in quantity 100 or 59 cents in quantity 1. Cheaper if you don't want the strain relief.

[Andy Gelme]

hi All,

On 2012-08-6 08:16 , Alec Clews wrote:

I've been put in touch with someone in Sydney who is distributing the Pi-Face IO board

I'm guessing the cost would be around $50-$70 (I'm totally guessing based on GBP30 cost in UK) but the price  is being worked out.

A good alternative is the Gertboard, which has just been announced as ready (finally) ...

�� http://www.raspberrypi.org/archives/1734

They can be pre-ordered from element14 (yet more waiting) for AUS$62.70 (inc GST).

It is a kit (not pre-assembled).

You get more capability compared to the Pi-Face I/O board.� The Gertboard includes ...

• 12x buffered I/O

• 3x push buttons

• 6x open collector drivers (50V , 0.5A)

• 48V, 4A motor controller(via GPIO PWM)
  

• 28-pin dual in line ATmega microcontroller (connected via UART)

• 2-channel 8/10/12 bit Digital to Analogue converter (MCP4802 via SPI)

• 2-channel 10 bit Analogue to Digital converter (MCP3002 via SPI)
  

I particularly like having a microcontroller on-board, which can handle time-critical hardware control and even more expansion.

[Luke Weston]

There's a few things I dislike a little bit about the Gertboard, such as:

- There doesn't seem to be any mention of what license applies to it, is it closed, or is it open hardware? Yes, you can find the schematic on the web, but that doesn't make it open. That's more significant with Gertboard than with the Raspberry Pi itself, because lots of people are likely to be making derivative hardware in this space, whereas getting access to the BCM2835 chips means that it's unlikely that we'll see Raspberry Pi derivative hardware emerging in the same way.

- Doesn't have rounded corners. 

- Ugly green soldermask.

- It's a very "busy" board with lots of devices and lots of flexibility packed in there, but there are lots of jumpers that need to be patched together, and it's not intuitive or easy to use without having to first carefully read through the long manual. It's very complicated, arguably it's trying to do too much, and that can detract from usability.

But those aren't greatly significant complaints. :)

[tubular]

I think it's a good start for an i/o board.  At least it has mounting holes, and easy enough to construct.   

Some comments by Gert van Loo about its open-ness here 

http://www.raspberrypi.org/phpBB3/viewtopic.php?f=42&t=14107 

My major complaint is it doesn't seem to be designed to fit a particular case (yes we could 3d print one).   

I've ordered a blank GertBoard pcb ($9.50 from e14, combined with $38 pi goes above $45 req'd for free shipping)

cheers

Lachlan

[Michael Borthwick]

I have plenty of ATMEGA8 IC's if you need one.