Author Topic: what uC + touch-screen dev-kit?  (Read 5657 times)

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Online Rasz

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Re: what uC + touch-screen dev-kit?
« Reply #15 on: May 16, 2013, 07:50:53 AM »
if you want to put a tablet inside something you cant buy a 700$ ipad..


no, if you want to put a tablet somewhere put a $43.80 tablet there
http://dx.com/p/jxd-s18-4-3-resistive-screen-android-4-0-mini-pad-tablet-pc-w-tf-wi-fi-g-sensor-black-161536

this has better specs than any dev kit :) and you can learn android on it
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Offline nctnico

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Re: what uC + touch-screen dev-kit?
« Reply #16 on: May 16, 2013, 11:46:11 PM »
PID loops in a RPi that is running a full blown OS with undetermined response time seems like a great idea  :palm:
No problem at all. Just use a timer interrupt like on a microcontroller.

Online Rasz

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Re: what uC + touch-screen dev-kit?
« Reply #17 on: May 17, 2013, 02:08:54 AM »
PID loops in a RPi that is running a full blown OS with undetermined response time seems like a great idea  :palm:
No problem at all. Just use a timer interrupt like on a microcontroller.

interrupts have non deterministic response time under linux (or any other preemptive os)
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Offline nctnico

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Re: what uC + touch-screen dev-kit?
« Reply #18 on: May 17, 2013, 04:09:18 AM »
If that where true then a lot of hardware wouldn't work. You shouldn't expect nanosecond accuracy on the execution of an interrupt (just like on a microcontroller) but sub millisecond shouldn't be a problem at all.

Offline ddavidebor

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what uC + touch-screen dev-kit?
« Reply #19 on: May 17, 2013, 04:23:44 AM »
Use a pc type processor to control this tipe of things is just complicated and unreliable.

I will never buy something done that way.

Offline nctnico

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Re: what uC + touch-screen dev-kit?
« Reply #20 on: May 17, 2013, 06:40:52 AM »
And yet some industrial control systems work that way. Often the ethercat protocol is used to control I/O modules where the processing is done on a PC (and sometimes time critical things are done inside the interrupt service routine of the ethernet card!). If you are willing to pay then HP offers a wide range of very stable PCs.

Besides. I thought we where talking about some embedded (ARM) device.

Offline ddavidebor

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what uC + touch-screen dev-kit?
« Reply #21 on: May 17, 2013, 06:43:13 AM »
Why si much trouble when you can use a 5$ micro

Online Rasz

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Re: what uC + touch-screen dev-kit?
« Reply #22 on: May 17, 2013, 10:57:44 AM »
Why si much trouble when you can use a 5$ micro

5$ micros dont have fancy touchscreen UIs
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Offline ddavidebor

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what uC + touch-screen dev-kit?
« Reply #23 on: May 17, 2013, 02:52:16 PM »
But 5$ micro can do pid!

And work, work without a boot, an os, a fu****g java virtual machine and a damn touchscreen!!!!!

Do you understand?

Online SeanB

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Re: what uC + touch-screen dev-kit?
« Reply #24 on: May 18, 2013, 02:30:06 AM »
So can a quad opamp and a few passives, and lasts generally decades in industrial service.

Offline brainwash

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Re: what uC + touch-screen dev-kit?
« Reply #25 on: July 01, 2013, 10:59:09 AM »
I'm in the process of building a similar lab instrument and it will all be controlled from an Android tablet or phone since it's the easiest way to go. There will be some buttons, knobs and plain LCDs/digit displays but most of the stuff will be done via bluetooth.
There is no single solution for everything, I went with a modular design. Since a micro is <5$, even a dev board could be less than 10$ it's easier to just build a separate module for everything: programmable supply, battery charger, mini voltmeter/scope, signal generator, analyser/decoder, data logger, component tester, ...
A central module could handle all the connectivity (bluetooth, even serving a web page), RPi comes to mind here. Everything else communicates via a serial protocol to that module. You can also set up bootloaders on each module so that you can update the firmware via the central module.

Online Harvs

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Re: what uC + touch-screen dev-kit?
« Reply #26 on: July 04, 2013, 12:47:20 PM »
A central module could handle all the connectivity (bluetooth, even serving a web page), RPi comes to mind here. Everything else communicates via a serial protocol to that module. You can also set up bootloaders on each module so that you can update the firmware via the central module.

If the tablet and central module have access to a wifi router, another option is using wifi.  Using something like a RPi and android tablet with wifi and sockets is a rather pleasant experience to develop with, and potentially cheap.  Sockets isn't any harder than serial once you get your head around it.

I'm sure bluetooth is fine to, it's just another option.

Offline brainwash

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Re: what uC + touch-screen dev-kit?
« Reply #27 on: July 04, 2013, 04:01:12 PM »
I mean the small embedded modules communicate via serial (rs232, i2c, spi, ...) to the central module. Of course the central module talks to the outside world via TCP/IP or BT.
Unfortunately 802.11a/b/g does not have such a huge reach on the hobbyist market, perhaps this will change in the future.

Offline cthree

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Re: what uC + touch-screen dev-kit?
« Reply #28 on: July 05, 2013, 02:35:02 AM »
Because this cheap tablet has an expected life of 2 year

Extraordinary claims require extraordinary evidence. Where do you get the 2-year life expectancy rating from?

I've not seen a tablet die in under 2 years that wasn't being seriously abused. I still have a first-generation iPad that works like a freeking champ (used several hours per day). In fact, I kind of wish it would break so I would have an excuse to buy a new one with one of those pretty Retina displays... but the thing just won't die. And all of the Android tablets I have seen were similarly robust.

A iPad isn't a cheap tablet, even the first one. You're spoiled. Check out some of those $69 Android gingerbread hunks of garbage if you want to see a cheap tablet. I think 2 years is generous for some of them.

Offline Christe4nM

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Re: what uC + touch-screen dev-kit?
« Reply #29 on: July 05, 2013, 05:47:28 AM »
@Topic Starter:

Seeing those specs I had to think of the NXP LPC178x / LPC185x or FreeScale Kinetis K70 as possible candidates.
Devkits: LPC1788; LPC1857; FreeScale Tower System

For an RTOS take a look at FreeRTOS.

NXP has a nice deal with Segger that includes free (commercial) use of their emWIN GUI libraries (no source code though) as long as you use an LPC micro. Also NXP has some free USB libraries for their micro's. Haven't used either myself yet though.

The thing is, I'm not sure if any solution that fits your needs will be really small and cheap. Those micro's with LCD, Ethernet etc will cost anywhere from €8 to €15 depending on peripherals, supplier and how many you buy. On the other hand, maybe you could go for a multiple small (and dedicated) micro solution.


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