Interfacing with a LCD/tablet dash

Hardware inside and outside of the ECU
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skeeters_keeper
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Interfacing with a LCD/tablet dash

Post by skeeters_keeper »

It seems like one of the first things I'd like to do is have a way to display a "digital dash". I like TunnerStudio - but driving around with my laptop on the passenger seat doesn't seem like a great long-term solution. I don't think the STM32 can handle a display or running TunnerStudio, in addition to functioning as our ECU... so I see two options:
1) use a USB interface to another board, such as a Raspberry Pi, which is running TS and have that display to a 7" display in the dash
2) use Bluetooth (or usb) to connect to a tablet running TS or shadowDash (for an android tablet)

I'm inclined to think the tablet may be easier and more versatile... would a bluetooth interface be easy enough to set up with the STM32? Anyone have a suggestion on a tablet that would be good for this? I'm thinking almost any cheap tablet would be good enough for a dash.
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Re: Interfacing with a LCD/tablet dash

Post by AndreyB »

Wait a second. I am not getting what you are saying.

You begin with
I don't think the STM32 can handle a display or running TunerStudio, in addition to functioning as our ECU
but then you suggest we
use Bluetooth (or usb) to connect to a tablet running TS or shadowDash (for an android tablet)
This just does not make any sense to me. What exactly do you refer to by "handle TunerStudio"?

Obviously stm32 is absolutely capable of providing data to an external device - it could be a laptop, a tablet or a DIY tablet made of a Raspberry PI. Do you mean that we cannot launch TunerStudio directly on stm32? Oh yes that's for sure, at least because TunerStudio need a full-scale device and stm32 is an embedded micro controller :)

We have an open ticket http://sourceforge.net/p/rusefi/tickets/14/ for Bluetooth. As soon as we get a developer willing to contribute, this would go forward :)
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Re: Interfacing with a LCD/tablet dash

Post by AndreyB »

PS: and it's not so simple with STM32 not capable of driving an LCD directly.

First of all, our stm32f407 is absolutely capable of driving text LCD displays. The largest one I could find in 30 seconds was 20x4 - http://www.ebay.com/itm//281161739370 - but that's already at least something.

As for graphics LCDs, again - even stm32f407 can drive the smallest one, and we probably have enough resources to afford controlling them right from ECU. The problem with these ones would be that all these LCDs are tiny and we are limited by amount of RAM we can allocate for a screen buffer. The cheap LCD screens are cheap because they do not have the memory, and the whole problem with larger LCDs is not with CPU but with RAM - someone has to store the picture in memory, either the LCD controller or us.

But things are going forward - there are newer and just more powerful MCUs in the stm32 family

For instance look at STM32439I-EVAL - it has a tiny issue of a $550 price tag, but I suspect it would be capable of acting as an ECU and DASH at the same time. But at this price it's cheaper to get a tablet. So, let's get to work on the Bluetooth functionality :)
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Re: Interfacing with a LCD/tablet dash

Post by frig »

would a bluetooth interface be easy enough to set up with the STM32?
Yes. Something like HC-04 or HC-05 connected to uart. Shadowdash on android tablet works good on this setup.
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Re: Interfacing with a LCD/tablet dash

Post by AndreyB »

frig wrote:Yes. Something like HC-04 or HC-05 connected to uart. Shadowdash on android tablet works good on this setup.
Have you actually tried this already? Would you be willing to write a detailed HOWTO? :)

I have one of these "New High Quality Wireless Bluetooth Transceiver Module RS232" from eBay but I have not yet tried wiring them up.
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skeeters_keeper
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Re: Interfacing with a LCD/tablet dash

Post by skeeters_keeper »

Sorry for not being as clear as I could have been, russian, but you answered my questions perfectly!

I knew the STM32 could drive simple displays - but I wasn't sure if it would be enough to actually display a dash. From what you said it sounds like it would be on the hairy edge and would probably be better left to an external tablet that just receives data from the stm32. Besides, why re-invent the wheel when ShadowDash is a nice looking app for only $10, and can log data and use the GPS/accel that is in the android tablet.

I think I will try to get a tablet for Christmas, and then work on the bluetooth link.
Perhaps something like this cheap one which has bluetooth but no GPS
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Re: Interfacing with a LCD/tablet dash

Post by kb1gtt »

I got one of those nextbooks and I'm a bit disappointed. It does not allow for the playstore to be installed, so it's quite difficult to get programs installed. I'm looking to see if I can get a different OS installed on it, as it appears the playstore issue is purely a software issue not a hardware issue. Also the nextbook seems to have blah software installed, so I'm thinking it should have a different OS before it's used for a dash display. I'm finding that browsing with one web page is often slow and seems to fail often. I would really think that should work but it just plain seems buggy. On a good note, I left it out side last night, it got down to around 0C and it seems to still work fine. So it did OK at low temperatures.

Does anyone know where or how I can install a different OS on this that might be a better platform? So far I have failed with http://www.cyanogenmod.org/
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jedediah_frey
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Re: Interfacing with a LCD/tablet dash

Post by jedediah_frey »

There are a ton of cheap tablets out that have bluetooth and you can use a full keyboard with.
erich
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Re: Interfacing with a LCD/tablet dash

Post by erich »

The Discovery board it totally is fast enough to run an LCD display.
I run one of these in my car: http://www.ebay.com/itm/new-7inch-7-0-800-480-TFT-LCD-Module-Display-Touch-Panel-SSD1963-For-51-AVR-/111140237971?pt=LH_DefaultDomain_0&hash=item19e0797293
The discovery board runs datalogging for the engine, talks to the stock ECU to pull out real time data and decodes MP3s.
Understand that the Discovery board is about as fast as a Pentium 133. There were a whole lot of video games that ran just fine on that hardware.

Now, if you're doing the engine management via software timing the display updating will get in the way as it's a CPU heavy load.
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Re: Interfacing with a LCD/tablet dash

Post by kb1gtt »

If one chooses a tablet, I'd suggest picking one from this list http://wiki.cyanogenmod.org/w/Devices#vendor=; that will allow much more flexibility from a developer stand point.
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TheHeckler
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Re: Interfacing with a LCD/tablet dash

Post by TheHeckler »

If you can deal with a small dash there is an ST unit wirh LCD
https://my.st.com/st-extranet-web-active/active/en/catalog/tools/PF259090
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Re: Interfacing with a LCD/tablet dash

Post by AndreyB »

TheHeckler wrote:If you can deal with a small dash there is an ST unit wirh LCD
https://my.st.com/st-extranet-web-active/active/en/catalog/tools/PF259090
2.4" QVGA TFT LCD is unrealistically small
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Re: Interfacing with a LCD/tablet dash

Post by acab »

I think we can add support of that multifunction gauge:
http://www.plxdevices.com/product_info.php?id=MULTDM6
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Re: Interfacing with a LCD/tablet dash

Post by AndreyB »

acab wrote:I think we can add support of that multifunction gauge:
http://www.plxdevices.com/product_info.php?id=MULTDM6
You know where to send your patches :)
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Re: Interfacing with a LCD/tablet dash

Post by acab »

I very lasy for that)!
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