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1  Using Arduino / Programming Questions / Re: New to Arduino - help converting float on: July 29, 2014, 03:56:45 am
From what I can google, I believe that it is
Code:
ble_write(unsigned char)/code]

You can send ASCII or binary data, it is up to the application at the other end to process it appropriately.
2  Products / Arduino Due / Re: error compiling on: July 29, 2014, 03:42:12 am
The first problem is that you need to select Arduino Due in the Tools -> Boards menu.

The second problem may be that some of your libraries are specific to AVR, and will need updating.
3  Using Arduino / Programming Questions / Re: Hardware Serial Confusion - using LinkSprite RS485 hardware. on: July 28, 2014, 03:50:51 pm
I write the request for data to the device, the device waits 10mS after the stop bit, then responds. I have a 100mS delay between the end of writing and the beginning of reading.  And yet, there is data to read long after the device has transmitted it. There is something I don't understand here - any thoughts?

The comment in your code is correct, data received is buffered until you read it. The buffer size is probably 64 bytes.
4  Using Arduino / Microcontrollers / Re: Intel Galileo has integrated linux OS on: July 27, 2014, 11:34:42 am
I read somewhere that Microsoft will be doing Galileos with Windows running on them, their attempt to get into IoT.
Microsoft makes a lot of announcements.

Heh, true. They recently updated the webpage http://dev.windows.com/en-us/featured/Windows-Developer-Program-for-IoT

Their plan appears to be Windows apps plus Intel hardware plus Microsoft cloud. From their recent efforts with smartphones and tablets not sure how well that will work.
5  Using Arduino / Microcontrollers / Re: Intel Galileo has integrated linux OS on: July 27, 2014, 07:47:47 am
I think that companies like Intel would have no interest in the "maker community" except that the "Internet of Things" is predicted to be huge, and the last thing Intel want is to see billions of things with someone else's CPU in them, even if Intel don't actually have a suitable CPU.

The Galileo does have the air of a very bodged rush job, even though done by a team with lots of resources.

I read somewhere that Microsoft will be doing Galileos with Windows running on them, their attempt to get into IoT.

As for Linux sources and documentation, good luck with that! I recently went to a 3 hour seminar on building and configuring Linux using yocto, the presenter explained it was just a quick overview, the full presentation took 3 days  smiley-eek-blue I admit I ducked out at the first break...
6  Using Arduino / Programming Questions / Re: on off swich on: July 27, 2014, 07:27:56 am
I disagree, years of experience tells me always debounce switches!

7  Using Arduino / Programming Questions / Re: I'm having trouble getting my stepper motor to turn once every hour on: July 27, 2014, 05:44:34 am

The motor also gets a lot hotter than usual. What do I have to change in my code to set things up correctly to control the motor in 1/4 stepping mode? Hopefully that will get rid of the squeaking and cool the motor down. If there's anything else that looks wrong in my code please let me know.

Sounds like your stepper driver is getting hot and shutting down, then restarting. This is consistent with the motor getting hot - it is drawing a lot of current. You either need to put some cooling on the driver, reduce the current limit or use a bigger driver.

The squeaking is probably normal for any microstepping driver, they use PWM to control the current. Often some of this ends up in an audible band. It may be possible to tune out the noise, depends on the stepper driver.
8  Development / Suggestions for the Arduino Project / Re: Does Arduino have a future? on: July 27, 2014, 05:31:32 am
The architecture of AVR or cortex CPUs is essentially the same as those of 50 years ago, and in that time people have been wrestling with the problem of bare-metal vs OS.

Unfortunately, there is no way to create OS-like functionality without incurring some overhead.  The more independence of processing that you want, the more overhead you need. This is an inevitable feature of several processes sharing a single CPU core, memory and peripherals.

Fortunately, the hardware guys keep making faster chips, so we get round the problem that way. The alternative is to have independent cores, e.g. like the Parallax Propeller. But I am pretty sure there is no software trick to get the best of both worlds.

There is a niche at the bottom end for bare metal systems, and I think the basic Arduino will continue to provide an entry level type system for that. It's also clear there is demand for systems with rich environments like Raspberry Pi. The price/performance of those will continue to improve, and the price get closer to that of Arduino, if not already there.

What will probably not change is the middle ground, between bare metal and feature rich OS like Linux. For example, I would like to add TCP/IP, web server, USB host with support for wi-fi dongle to my bare metal project. That's a big chunk of code. There is no obvious off the shelf solution, or "go to" RTOS which supports all that out of the box.

The problem is that there are thousands of RTOS to choose from, but drivers and middleware for them is lacking. I think this is one area where diversity doesn't help, and a single standard would allow people to develop drivers and middleware instead of re-inventing the RTOS.

Perhaps the Japanese had the right idea with ITRON, but a government funded standard seems like anathema to the western way of doings. ITRON is claimed to be the most widely used OS (units shipped), but few people have heard of it.

Ironically, an old version of Unix might be a good real time OS, at least for 32 bit devices. It has a simple clean architecture and is well known.

The gap between 16MHz 8 bit AVR, and a 500MHz 32 bit ARM with 4MB RAM (roughly where Linux becomes runnable) is too big to be bridged with a single RTOS. It should be possible to scale from say 50MHz ARM with 32KB upwards on a single RTOS, but chips with a few kB of RAM will be too resource constrained to run anything more than a very basic RTOS if at all.

So I think Arduino will continue as a cheap and simple way to interface to electronics, systems like Beaglebone will reach the price point of Arduino, and the problem of the middle ground between bare metal and Linux will continue.

Perhaps the answer is dual function boards like Arduino Tre and UDOO, with a fast interface between the low and high level CPUs.
9  Products / Arduino Due / Re: About Serial.print() function for DUE on: July 26, 2014, 11:04:11 am
These measurements are misleading. At 115200, the speed of transmission is exactly the same for Mega and Due.

The difference in Due is that the write blocks, so you waste time waiting. So if you have other stuff to do, it could be made more efficient, but you won't be able to transmit faster. The Mega appears faster because it has not actually sent the data, it has just put the data into a buffer.

In the worst case on Mega, if the transmit buffer is full, then you still end up waiting.

However, I can't see any good reason why the Due should not support a transmit buffer, I think it would be quite easy to add. With the new availableForWrite function, the user can maximise the amount of processing done while waiting for comms, and perhaps minimise latency between transmissions.

I will have a go at creating a patch.
10  Products / Arduino Due / Re: Due for very low power applications? on: July 21, 2014, 07:35:54 pm
I would try to start with a design that is designed for low power, but it might be simpler and almost as good to control the Due power with a small extra circuit. This type of thing is described here http://alanbmitchell.wordpress.com/2011/10/09/design-of-the-extended-battery-life-power-controller-for-the-arduino/

Atmel and Microchip do some low power 8 bitters which could act as power controller. If you have the electronics-fu you could probably get down to nA or something, but for 1-2uA having a micro is a lot more flexible to run timers, wake on int, shutdown request etc.

Of course the Due would need to store its state before powering off, there are a number of ways to do that.
11  Products / Arduino Due / Re: Problems programming the Due on: July 21, 2014, 04:41:30 pm
This is puzzling. I don't think that adc12_sam3u.c should even be in the build, because as the name suggests it is for SAM3U not SAM3X. adc.c is the file for the SAM3X.

Poking about in hardware\arduino\sam\system\libsam, it seems that the makefiles support SAM3U and SAM3X targets. I guess this stems from the time when they weren't sure to use SAM3U or SAM3X.

I can't see that the gcc make files would work at all, but the IAR project excludes adc12_sam3u. The implication is that Arduino must use IAR to build the due_x library?

tldr; just delete adc12_sam3u.c !

Edit: I think I was looking in the wrong place, the make files for libsam_sam3x8e_gcc_rel.a are in hardware/arduino/sam/variants/arduino_due_x. But, I still can't see how the library is built from there. I would like to figure this out, because I want to create a patch to enable the watchdog!
12  Products / Arduino Due / Re: Problems programming the Due on: July 21, 2014, 01:55:39 pm
From the date of the fiddling script, it was written sometime in 2013-09 and the Due library has certainly changed since then. It would be good to know which version of IDE Willy used at the time, but I can't see that written anywhere.

The file that make fails on is adc12_samu.c in libsam/source. The offending line is possibly "#if SAM3U_SERIES" if SAM3U_SERIES is not defined. (It's not good coding style).

Finding the source of the error might be rather difficult, but a workaround might be to define SAM3U_SERIES and see what happens. It would help to know what the previous IDE used was and compare the differences.

I've had similar problems with standalone Due projects that used to work with one IDE version then stop working on another, I don't think there is a way to avoid that until the IDE has stabilized.
13  General Category / General Discussion / Re: Compilation on: July 20, 2014, 07:03:23 am
If you want to have a go at building a computer from scratch, have a look at some of the home-built computers, like this one http://www.electronixandmore.com/projects/relaycomputertwo/index.html

Not a practical way to build a computer, but the result is almost like kinetic art.

14  General Category / General Discussion / Re: Good career options for arduino enthusiasts, and similar tech minded people? on: July 20, 2014, 06:45:21 am
In my experience, there are few opportunities for that sort of person. The type of stuff people generally do hobby-wise is really tip of the iceberg compared to industrial scale projects, and there must be a very small number of companies trying to produce "fun" type electronic gizmos.

Having a hobby interest is good because it demonstrates an interest in the subject, but for nearly all jobs you need the depth of expertise that college provides. In fact you usually need more, but college shows you have an ability to study stuff you may not be interested in. Unfortunately most jobs are 20% interesting and 80% boring stuff you have to do. Endless days in the lab testing...






15  Using Arduino / Motors, Mechanics, and Power / Re: Stepper motor jitter on: July 20, 2014, 02:23:26 am
The AF_Stepper class does not appear to implement acceleration profiles? If you are stopping without acceleration, then the moving mass will cause some oscillation about the final step point.  In the worst case it could lead to missed steps.

It appears that using this library microstepping doesn't work with single steps, the library starts and stops on a full step. You would need to perform a multiple of the microstep interval (16 may be the default) per call to get proper results.

Which version of the motor shield have you got? The V1 motor shield and library are pretty basic, you may struggle to get precise operation from it. The v2 board looks better, but a4988 driver or similar and accelstepper might be a better option.
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