gbulmer
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Re: Break out board (GPIO, SPI, I2C, and UART)

Tue Nov 08, 2011 4:39 pm

Quote from liz on November 8, 2011, 16:13
Just to muddy the waters even more, I should add that we (the Raspberry Pi Foundation) do plan to make some add-on boards ourselves next year.

liz - I think that is an extremely helpful statement. My interpretation is, the R-Pi *STANDARD* hardware interface will be the physical layout of sockets and electrical signals that R-Pi add-on boards use.

It also encourages me to hope that R-Pi designers will try to make the sockets easy to get at :-)

Bacan
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Re: Break out board (GPIO, SPI, I2C, and UART)

Tue Nov 08, 2011 4:41 pm

Liz:: Why not just make a R-Pi Hacker/Maker/Experimenter board?

Use all the PCB layout space needed to properly
* expose all the allowable Broadcom SoC signals,
* put on sockets for Lots and Lots of card type plug in RAM, not POP RAM
* put headers for every type of video out the SoC supports: HDMT, Composite, ?LCD/LED?, ...
* GPIO on standard & sturdy connector pin row
* put USB chip & Eithernet chip
* Real Time Clock
* stacker connectors for specialized IO cards
* plus what ever else the Crowd Source desires and votes for.
* put the connectors in the back edge, and blinky LEDs on the front edge

And charge $100+USD to us 1st world Geeks & Hacker people.

Just my opinion.

[Added] Oh ya! Make it 2 layer, so Want-ta-be designers can learn from the released design plans.

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abishur
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Re: Break out board (GPIO, SPI, I2C, and UART)

Tue Nov 08, 2011 5:05 pm

Well, I was going to give a detailed response... but the long and short is that to provide the kind of board you're talking about would mean a complete reworking of every last component! Plus from what we know of the SoC and what they're using, the little pieces they're not making use of are pieces that wouldn't be used anyway expect in extremely strange situations, just not as useful as we would hope for the end user :(

Also, if you're willing to pay 100+USD then what you've just described is the beagleboard/pandaboard. Why reinvent the wheel? ;)
Dear forum: Play nice ;-)

gbulmer
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Re: Break out board (GPIO, SPI, I2C, and UART)

Tue Nov 08, 2011 5:05 pm

Bacan - a bit off topic, but let me try ...

I very strongly recommend you read "Crossing the Chasm", and you can start here:
http://en.wikipedia.org/wiki/C.....asm_(book)
that will give one explanation about "why not".

Have you ever watched "Dragon's Den"?
The way it works is *YOU* go in and say "This product will make this much money. Here is the business case, here is the analysis. This is what it costs to make in this volume. Based on this market research, this is the size of the market, and how many we can sell, and at what profit margin. I need this much money to get to market."

It doesn't work by you going in and saying "if you stopped what you are doing, throw away much of the research, change the target market, and make this instead, I would buy one. Put all of your effort into this instead."

Does that explain "Why not just make a ...(different thing)" is not the best question to start with?

IMHO, I do not think it is R-Pi's problem to explain "why not", I think it is your problem to explain "why".

The act of doing that for yourself is likely to throw up good questions, which might lead you to explanations of "why not", or identify extra opportunities that R-Pi may be under resourced to investigate and exploit.

Just my $0.02 worth

hippy
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Re: Break out board (GPIO, SPI, I2C, and UART)

Tue Nov 08, 2011 5:15 pm

Quote from Bacan on November 8, 2011, 16:41
Liz:: Why not just make a R-Pi Hacker/Maker/Experimenter board?


Something along those lines seems reasonable. All the components ( except headers ) would be same as a normal R-Pi board so it's really just another PCB design.

Quote from Bacan on November 8, 2011, 16:41
And charge $100+USD to us 1st world Geeks & Hacker people.


I'd pay a fair price for the board, would accept a reasonable premium for what it gives, the extra cost of design and production, but at that price I'd also be looking at Beagleboard and other alternatives. I'd also have to weigh-up whether that $100 really gave me anything better than a $25 R-Pi and some other solution.

----

Any way, we still seem no closer to having anything like a simple breakout board for those people who want to go beyond soldering to header pins or fanned-out ribbon cable if they can find such a thing, which is what those wanting to play with R-Pi hardware interfacing will be looking at when the boards turn up in a month or two.

Admittedly there's not a lot which can be done until we know what GPIO connections there are and perhaps where they are placed.

Bakul Shah
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Re: Break out board (GPIO, SPI, I2C, and UART)

Tue Nov 08, 2011 6:47 pm

Bacan, Why not just use the Beaglebone?

Bacan
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Re: Break out board (GPIO, SPI, I2C, and UART)

Tue Nov 08, 2011 8:16 pm

Quote from abishur on November 8, 2011, 17:05
... kind of board you're talking about would mean a complete reworking of every last component!

I am typing about a HME board, in addition to, not in place of Model A or B cards.

Why reinvent the wheel? ;)

Profit from sales goes to R-Pi Foundation.

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Gert van Loo
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Re: Break out board (GPIO, SPI, I2C, and UART)

Tue Nov 08, 2011 8:23 pm

Ok, I can reveal that I have been working on a simple I/O extender card. Note: It is my own development and is not (yet) official Raspberry Pin foundation work. I can do that because I have seen the initial version of the final board. I can't finish my design until the final board is done and I have the risk that I have to re-route the whole design if the board designer decides to move the connector or swap a lot of pins. My plan is to make four prototypes and debug them as soon as the first real boards come out. (I might needs some help with that...) If they work I will release the full details, schematics, documentation, Gerbers etc. Maybe the Raspberry Pi foundation is willing to make a number of boards and sell through their website, or not!
I started this because several teachers wanted to teach 'driving hardware'. So this is intended as a teacher board. it has:

- 12 general purpose I/O buffers to be set for Input or Output (Solder jumper) with a LED per buffer.
- 6 open collector relay drivers.
- L6203 (Multiwatt) 4A motor driver (with fuse)
- PIC18F2xK20_28 (or pin compatible) connected to the SPI bus
- MAX 7317 SPI extender IC
- Two LDO regulators.

There are two opposite rows of holes, one to the GPIO pins and the other to the logic. You have to select which GPIO pins you connect where. e.g.
6xbuffer (2 in 4 out), 2x relay, 2 PWM** wires to the motor.
or
4 GPIO (SPI) to the PIC plus 12xbuffer (10 in, 2 out)
With a bit of luck the board may be available a few weeks after the first PI boards.
Board cost estimate is ~$4 but gets lower if we can order large quantities. You have to assemble it yourself so you can also decide which parts you want and which parts not. Assembly is not difficult as all components except the MAX 7317 are huge. Smallest SMD is 0805).
The board is two layer with minimum track width and spacing of 0.254 mm (Except the SMD footprints).
Caveat: I am not very good PCB layout engineer. You have to live with what I make and I leave it for others to take it and improve it. This is just my attempt to get something out there for you guys ASAP.
**Note if you use PWM for the motor I strongly suggest you do NOT play music!

Bacan
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Re: Break out board (GPIO, SPI, I2C, and UART)

Tue Nov 08, 2011 8:41 pm

Thank you for the book reference.

Personally, I find Four Steps to the Epiphany by Steven Gary Blank
a more robust exercise and resource in business planning and product development. FYI: for the past ten years I've been aiding early stage ventures with planning, capital presentation, and process sequencing. Maybe a thread for R-Pi 3rd party start-ups would be useful. Oh ya, VARs thread. Got shot down in flames here in the forum.

Yes, I'll be very happy to see the production release of A/B cards having a socket bringing out the GPIO and any extra SoC signals that would be useful. I say socket, instead of pins because sockets will the better protect the SoC from stray Kid ESD than a picket fence of pins going right to the heart of SoC.

As for the Uber-board above vs a Beagle-"whatever". It feeds and grows the R-Pi ecosystem, uses the Broadcom SoC, and will be part of a product line from one single vender, for it's developer community. I'm not suggesting a "Walled Garden". Just maybe, less finger vendor pointing when something doesn't work.

bradburts
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Re: Break out board (GPIO, SPI, I2C, and UART)

Tue Nov 08, 2011 11:13 pm

Quote from Gert van Loo on November 8, 2011, 20:23
Ok, I can reveal that I have been working on a simple I/O extender card. !
Great, count me in!
What about software support, do you have that covered, do you need help?
$4 is a great price for a kit, low enough to encourage people to give construction a go and hopefully gain some educational benefit. Once bought an Acron Atom kit so expect a small self build interface board should be ok (kids today though.......)
There seems to be a bit of off topic discussion about business which in engouraging in a way, albeit maybe a little heated.
Its great that RPI foundation looking to add their own board but is this wise? If after a few months nothing appear from Gert and or ano then I suppose that RPI must provide a solution. Once RPI have a solution I doubt that anyone will buy a 3rd party solution.
If however RPI stand back for a while then 3rd party solutions will appear either through renumeration, helpfulness or top of the class motivations - each of these processes will help grow the RPI culture.

theomarkettos
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Re: Break out board (GPIO, SPI, I2C, and UART)

Tue Nov 08, 2011 11:23 pm

Hi Gert,

If you want me to look over your board I'd be happy to do that.

Theo
(with access to the final board, doing a lot of PCBs at the moment)

gbulmer
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Re: Break out board (GPIO, SPI, I2C, and UART)

Wed Nov 09, 2011 1:34 am

Quote from Bacan on November 8, 2011, 20:41
Thank you for the book reference.

Personally, I find Four Steps to the Epiphany by Steven Gary Blank
a more robust exercise and resource in business planning and product development. FYI: for the past ten years I've been aiding early stage ventures with planning, capital presentation, and process sequencing. ...
Wow! And you still ask "why not ...?".
I dof my cap to you for optimism :-)
Yes, I'll be very happy to see the production release of A/B cards having a socket bringing out the GPIO and any extra SoC signals that would be useful.

I say socket, instead of pins because sockets will the better protect the SoC from stray Kid ESD than a picket fence of pins going right to the heart of SoC.

As you will understand from reading this thread, there appears to be several different use cases, with different solutions.

As for the Uber-board above vs a Beagle-"whatever". It feeds and grows the R-Pi ecosystem, uses the Broadcom SoC, and will be part of a product line from one single vender, for it's developer community. I'm not suggesting a "Walled Garden". Just maybe, less finger vendor pointing when something doesn't work.

I am curious. As you who have been 'in the business' for 10 years, and hence understand how precious start-up resources are, and how key focus is, I'd like to understand your evidence, and the scale of the market.

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Gert van Loo
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Re: Break out board (GPIO, SPI, I2C, and UART)

Wed Nov 09, 2011 9:08 am

bardburst wrote: $4 is a great price for a kit,
Uh. I said ~$4 for the board. You have to kit it out yourself. So you can omit the parts you don't need. e.g. the L6203 is rather expensive and if you don't drive a motor, just don't buy the chip.

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Burngate
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Re: Break out board (GPIO, SPI, I2C, and UART)

Wed Nov 09, 2011 11:21 am

Quote from Gert van Loo on November 8, 2011, 20:23
Ok, I can reveal that I have been working on a simple I/O extender card. Note: It is my own development and is not (yet) official Raspberry Pin foundation work.
Great! I'll take two!
(just as gentle encouragement - a few months down the line, this would be a wonderful enhancement to the product line, along with SD cards, cases, &c.)

bradburts
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Re: Break out board (GPIO, SPI, I2C, and UART)

Thu Nov 10, 2011 9:20 pm

Quote from Gert van Loo on November 9, 2011, 09:08
bardburst wrote: $4 is a great price for a kit,
Uh. I said ~$4 for the board. You have to kit it out yourself.
Thought that was a great price ;)
May I suggest that you offer the board with, as a minimum, basic parts kit +$1 of protection diodes & resistor etc? Maybe also offer a pro version +$4 with parts for an ADC, DAC and a FET channel or two?
As I write and guess at the kit costs I am thinking that the ARDUINO solution is quite a good approach, cheaper and less tracks to lay.
Just need a good ARDUINO app & RPI driver......
Anyway postage is not cheap and so offering a kit of part allows you a good margin (against my need to pay for second postage to farnell etc) and/or a better kit of parts. There is also the hastle saved, I hate sourcing parts even when I know the part number.
If costs reach $15 then I would be looking for an assembled board with at least GPIO, ADC and DAC. So a kit at $8 would be nice.
Myself I would want a pre-built board with GPIO, ADC and DAC.
I don't know how many would want a kit, hopefully more than a few.

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liz
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Re: Break out board (GPIO, SPI, I2C, and UART)

Thu Nov 10, 2011 9:24 pm

Seeing as Gert did so much work on the hardware of the Raspberry Pi itself, it'd be idiotic of us not to give our official blessing to this add-on board. (Eben's supposed to have told him that already, but I think Gert was away earlier this week.) Consider Gertboard an official product!
Director of Communications, Raspberry Pi

Bacan
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Re: Break out board (GPIO, SPI, I2C, and UART)

Thu Nov 10, 2011 9:40 pm

Gertboard great product name.

What type of berry is a Gert? ;-)

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meltwater
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Re: Break out board (GPIO, SPI, I2C, and UART)

Fri Nov 11, 2011 10:29 am

+1 For the Gertboard.

Such a solution would be great for teaching etc, as far as I understood one of the aims for the R-Pi was to allow the I/O of a PC to be accessible again. Personally I'd love to set the R-Pi up and then try out a few experiments by clicking on an extension board.

I'd be quite happy with a DIY kit of parts and PCB, even a order list for farnel/maplins would be fine (long term probably not practical since as soon as the order numbers change the list is no good). With the design and a PCB to use, it should make it practical for most people to use.

When the release R-Pi is ready and checks out ok, please PM me if you are willing to send out a PCB and list of parts and I'll try it out...happy to help with assembly instructions on a wiki etc.

Ultimately even if the board is capable of performing a simple LED traffic light demo driven by the R-Pi, you have the spark for education. I can just imagine the link kids will make when they realise that computers can do more than play games and send emails and they can interface with the real world under their control. In some ways, it is more powerful than showing a PIC can do it, since they are used to computers which use graphical displays etc not chips with code hidden inside.

For me, I have plenty of "if I had the I/O interface to my software I could do this" ideas, the R-Pi should give the display, storage, connectivity and raw CPU for most projects so hopefully the focus can be on ideas and programming.
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kendrick
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Re: Break out board (GPIO, SPI, I2C, and UART)

Sat Nov 12, 2011 4:28 am

To have fun with Liz's muddied waters... A few things that dont seem to be looked at. though I may have just gotten lost in the techno babble... since I am planning to learn my hardware programing/electronics in the next few years through my companies tuition program :D

1) Rpi is to learn from and geared towards 3rd world countries. An older article (linux journal? 2002 ish i think) talked about 3rd world injinuity on a 486 or p75 running a hotel and its website on linux and other types of linux use on old hardware. Making it easy for them to plug in to a buss on that board would be a huge thing.

2) learning to make a robot makes flashing lights booring ;) programing the chips and building the sensors from the pi would make it that much more likable. for example a simple robot kit or even making it possible to tie in to the lego mindstorm? stuff. having usb being the only option would get quite limiting.

3) I plan to use these to control the sensors etc of my green houses and much more. They will be getting poe one way or another and may never be connected to video out.

Side note. a stackable bus would be awesome. There was an article a while back about a group that was clustering SBC's that were designed to connect to a standardized buss. it wasnt plc or cann based but similer automation/embeded standard. they had a lot of fun/success with parell computing doing things that way. I could see a 3rd world science department finding that useful where higher education is just starting to get built up and no real funding for it.

bradburts
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Re: Break out board (GPIO, SPI, I2C, and UART)

Sat Nov 12, 2011 10:05 am

Quote from kendrick on November 12, 2011, 04:28
Side note. a stackable bus would be awesome.
IEEE 802.3 works for me ;)
(Edit: sort off stackable with a hub/switch/router)
Seriously though, I think the interesting projects you are looking for, robots, lego will come in time.
There has been a lot of techno babble and this has been useful in determining what people want and therefore what a board should provide.
There won't be a single solution, there will always be a need to tinker and adapt. I don't think that I will find what I need, a low cost, low profile pre-built board with basic I/O protection but I will find the information and confidence within this forum to build it myself!

jg
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Re: Break out board (GPIO, SPI, I2C, and UART)

Sun Nov 13, 2011 11:05 pm

Quote from Gert van Loo on November 8, 2011, 20:23
Ok, I can reveal that I have been working on a simple I/O extender card. <snip>

- 12 general purpose I/O buffers to be set for Input or Output (Solder jumper) with a LED per buffer.
- 6 open collector relay drivers.
- L6203 (Multiwatt) 4A motor driver (with fuse)
- PIC18F2xK20_28 (or pin compatible) connected to the SPI bus
- MAX 7317 SPI extender IC
- Two LDO regulators.


<snip>Caveat: I am not very good PCB layout engineer. You have to live with what I make and I leave it for others to take it and improve it. This is just my attempt to get something out there for you guys ASAP.


Sounds great, If you post the design somewhere, I'm sure it can be quickly improved, if needed.

The 'magic-sauce' is things like connector placements, pin allocates and mounting holes, and that is best passed as CAD files.

Q: What PCB design system is this in ?

Q: What package is allowed for on PIC18F2xK20_28 ?
I'm guessing _28 means 28 pins ? DIP or SO ?
Microchip have just released a PIC32 variant (PIC32MX120F032B) in SkinnyDIP28(300mil), so that could be a good package for teaching, with a wide-breadth of 'horsepower'.
{ I also see the new 70 MIPs dsPIC33EP64MC50X mentions SDIP28}

(NXP also now do 32bit in DIP28, but theirs is 600 mil ?!? )

Suggestion: As well as the Microcontroller, can you also add a smarter ADC, like this one ?

http://www.ti.com/product/ina2.....=ina226-pr

The INA226 has 36V DC direct measure, and current (80mV) and even measures power. All to 16 bits.

So is great to Read-back motor, and will also make good Solar power teaching.

It uses i2c to communicate, and is in a small MSOP10, and can pretty much connect directly to loads. (no complex dividers/amplifiers)

hippy
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Re: Break out board (GPIO, SPI, I2C, and UART)

Sat Nov 19, 2011 2:45 am

Does anyone know if there's a hardware 'reset' pin for the SoC available via GPIO, JTAG or other connector ?

And if there is; does it put the SoC into a low / lower power consumption mode while asserted ?

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abishur
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Re: Break out board (GPIO, SPI, I2C, and UART)

Sat Nov 19, 2011 4:14 am

Well, I don't know the first question. I think there was some general discussion about it, but nothing firm (so I'm planning on it being the official "if it has power it's on")

The second part I do know. Even if there was a reset pin or power/standby the GPU is extremely aggressive in it's power scheme. If there's an unused part it's completely off, which means as far as the GPU is concerned, there's really not power savings to be garnered by turning going into standby/lower power. As far as the other part of the SoC, we've been told that that would be dependent on the OS itself, but seeing as how we're talking about a couple watts, I'm not sure if there's any plan to try and make a low powered mode.
Dear forum: Play nice ;-)

WizardOfOZ
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Re: Break out board (GPIO, SPI, I2C, and UART)

Sat Nov 19, 2011 6:53 am

Haven't seen an active reset mentioned anywhere, though that doesn't mean it isn't there.

However if you need such a signal, then it is easy to build into the power supply. If you fed +5V to the Pi via, say, the GPIO port (which I believe *is* possible), then you can simply choose to use a PSU regulator with a shutdown signal.

That way you could still have power for your watchdog circuit/reset button timer if desired to ensure a proper system reset. Only drawbacks is that we may need two PSU regulators in some situations, and that the reset cycle itself may take longer to execute compared a 'true' hardware reset signal due to the need to wait for on-board capacitors to discharge.

hippy
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Re: Break out board (GPIO, SPI, I2C, and UART)

Sat Nov 19, 2011 11:34 am

Thanks abishur, WizardOfOz.

I think I've found the answer - nSRST on JTAG is a processor reset, though that reset may be combined with nTRST, depending on chip implementation.

I was really just exploring what options we had for restarting everything without power-cycling, having a cluster of R-Pi sharing a single SD Card and other idle musings; how to abort and restart errant bare-metal programs, download new images for bare-metal and own-OS programs without JTAG and without having to remove SD Card.

Using reset might also bring some options for battery powered R-Pi which are easier to implement than full power-cycling circuitry.

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