Very low-cost Android-based touch panel for HMI

You pretty much get Ethernet, Wifi, SD, RTC and battery with most of the high-volume Android offerings. The problem will be term of availability. For 7", there are a dizzying array of sub-$150 offerings. There's no cost savings by making your requirements more modest.

They do not, however, have RS485 natively.

Just IMO, but if I needed 485, I'd buy a Cubie or RasPi, plug a $5.00

485 adapter into one of the USB slots and connect to it via WiFi.

Android app development is pretty much a "walled garden".

--
Les Cargill

What quantity do you have in mind? Does it absolutely have to run Android? An old client of mine built something like that for their own application (retail kiosk) and it is quite nice, but runs a more generic Linux. Maybe they could work something out with you if you want enough of them. Their thing has a 3.5" touchscreen and uses a USB client port for power and network. It has an internal serial port so maybe that could be brought out as RS-485 with a little bit of customization.

For really big quantity you might try archos.com which can customize their hardware for you:

Do you think your price target is realistic? For $50 you will be hard pressed to find a small tablet which is about your specs minus the RS-485 plus a few very low cost peripherals. I would think they way to go is to find the lowest priced tablet you can and add a USB RS-485 adapter.

Even the Beagle Bone Black is $45 to start and that doesn't include the LCD or touchscreen.

--

Rick

OS. I'll use only the LCD, the touch panel and a serial interface (RS485) . A USB device port (to make a connection with a PC) and/or USB host port (for connecting USB pen drives) would be nice. The size of LCD could be fr om 5 to 7".

Sound like you don't really need Android. You are spec'ing out everything that need Android/Linux/networking.

ctions (like on Android smartphones).

Or just a good micro with touch screen LCD.

essed to find a small tablet which is about your specs minus the RS-485 plu s a few very low cost peripherals. I would think they way to go is to find the lowest priced tablet you can and add a USB RS-485 adapter.

Might be doable if qty is high enough. I am thinking perhaps in 10K pcs.

I have been looking for a low cost tablet with Bluetooth.

I have found a few, seems like BT is to costly for most manufactures to add.

There are some BT terminal programs out in the wild, but they do not always work with the tablets I have got.

I got a 7" Lenovo Ideatab A2107A-F (Ver 4.0.3) on sale and BlueTerm does work with it.

Now to get my own App to work with that.

hamilton

Il 06/09/2014 22:30, Les Cargill ha scritto:

I need to connect the touch panel to a RS485 bus, so I'd plug a USB/485 adapter to RasPi. I don't need WiFi at all.

I don't know, because I've no knowledge about development on Adroid. But I use Android-based smartphones and the human interactions through touch movements and graphics are very nice.

With a full features framework like Android, the final app will be very simple: sending/receiving messages to/from RS485 bus, put some data on display and get commands from the user through touch screen. I don't need to access any difficult hw devices.

I could use just Linux and abandon the idea to use Android, but the question will be: is it possible to create the same or a similar look&feel with bare Linux? ...without spending too much time to reinvent and rewrite the same things already written in Android OS?

Il 07/09/2014 00:38, snipped-for-privacy@gmail.com ha scritto:

But I need a LCD with a touch screen.

This is interesting. Do you think I could reach the same or similar look&feel of Android without Android? Could you suggest an OS and graphics frameworks or libraries to use? Mostly for touch management?

Yes, the quantity will be about 5k/10k.

id OS. I'll use only the LCD, the touch panel and a serial interface (RS48

5). A USB device port (to make a connection with a PC) and/or USB host por t (for connecting USB pen drives) would be nice. The size of LCD could be from 5 to 7".

er

ing that need Android/Linux/networking.

A high end micro can drive LCD and touch screen.

ractions (like on Android smartphones).

&feel of Android without Android? Could you suggest an OS and graphics fra meworks or libraries to use? Mostly for touch management?

You can still port part of Android/Java to your device. Think of it as a p icture frame with custom touch screen. If you don't need Wifi/Networking a nd flexible apps loading, you can reduce the RAM footprint and FLASH much o f your app.

pressed to find a small tablet which is about your specs minus the RS-485 plus a few very low cost peripherals. I would think they way to go is to f ind the lowest priced tablet you can and add a USB RS-485 adapter.

s.

There are picture frames for around $20 to $30. Upgrading the micro and to uch screen can be done for less than $20. If you device is always USB powe r/connected, you might not even need the battery.

But chances are you'd possibly have WiFi between the RasPi and the Android already.

Ideally, you *should* be able to build things such that either could work. I say that without that much knowledge of what building an Android app looks like.

Understood.

One point I'm trying to get across :) - RS485 is a largely alien technology in the RasPi/Android sphere. Paradoxically, WiFi isn't.

WiFi is also... wireless.

Pretty sure these work with just about all the RasPi class devices

I know they work with a Cubie running Lubuntu.

Either could work. I have no way of estimating cost of development for you doing the work. SFAIK, you will have to conform to the expectations of the Android SDK.

I don't think Ken Thompson done it that-away.

--
Les Cargill

In Android, you deal with socket at the low level and url at the high level, just like most standard software under UNIX/Linux. And in the old days, UNIX runs with serial connections, without Wifi.

As long as you have ppp, slip or something on RS485. Android/Java would not know or care about what's running under it.

But while they are similar, serial port connections aren't exactly the same API as for sockets. You talk about ppp/slip - to be sure. That's doable... but...

There's this:

Not exactly daunting, but still a parcel of work.

I've little doubt that's true, but I don't think you have to add anything to get WiFi on an Android, but you have to add an RS485 adapter and it'll be (possibly) quite a bit slower. If you can get things to agree to a 1/4 Mbit connection, then it's probably fast enough - although most likely it's still half-duplex ( and will have long turnaround times ).

If I make my guess, the Wifi dongle for a RasPi will be about the same cost as two RS485 adapters.

--
Les Cargill

I'd be tempted to look at the various Allwinner-based tablets coming out of China. AllWinner stuff is 'less bad' than some of the other cheapo SoCs as far as software openness goes - that means there's a little more of an ecosystem about it. Such a tablet is basically a touchscreen, the AllWinner SoC, and maybe a wifi chip and battery. Beware of the batteries, they may not be high quality - you could disconnect them if not needed. I'm assuming you'd want it rooted, so check there is root available.

In theory, if the innards are the same as other Allwinner tablets you're insured a bit from supply-chain issues: the SoC is the same so pick up another cookie-cutter tablet. Contacting the factory on Alibaba might be the way to get a more consistent supply (but be prepared for language issues).

But a warning: you're at the 'cheap junk' end of the market here. It may work, but what you save on ticket price you might spend instead on supply hassles. But could be worth it if the volume is high and the timescale is short (don't expect the same to be available next year).

Theo

Just ran across this:

It does state that it has RS485.

hamilton

of China. AllWinner stuff is 'less bad' than some of the other cheapo SoCs as far as software openness goes - that means there's a little more of an ecosystem about it. Such a tablet is basically a touchscreen, the AllWinne r SoC, and maybe a wifi chip and battery. Beware of the batteries, they ma y not be high quality - you could disconnect them if not needed. I'm assum ing you'd want it rooted, so check there is root available.

It would be difficult to meet the target price of $50. The Allwinner SoC s till need two external SDRAM and external flash loading SD. I am thinking of a single chip micro with 2M flash and 512K sram, with no external chips.

I did a search on Alibaba and found a number of units. Not sure of all the prices but $50 sounds like it could be in the range. Only one clearly supported RS-485 and showed a module in the image, but said it was an option. Some of the others said RS-485 in the list of features/interfaces, but weren't clear about it while others only mention RS-485 in the listing title. Still, it might be worth setting up a conversation with a few of them. Certainly this is the easy route to hardware if you can be sure they will be making them long enough to suit your needs. I guess you can always find a newer, similar unit if they stop making this one.

--

Rick

There is still usually a "blob" in the BSP parts for 'em.

The thing that might be important is to find the OTG port and image-off the NAND.

I know the Cubie boards have quite a bit of community for them; it's not clear that this is true of the tablets. And it's anything but clear how much they'd all have in common

You really kind of have to be your own escrow service. You can always eBay off extras.

--
Les Cargill

To clarify, you need a RS485 driver that supports operation on a multi-drop link, with addressed and broadcast reception, and/or master function? (as opposed to simple point-to-point)

m:

t of China. AllWinner stuff is 'less bad' than some of the other cheapo So Cs as far as software openness goes - that means there's a little more of a n ecosystem about it. Such a tablet is basically a touchscreen, the AllWin ner SoC, and maybe a wifi chip and battery. Beware of the batteries, they may not be high quality - you could disconnect them if not needed. I'm ass uming you'd want it rooted, so check there is root available.

still need two external SDRAM and external flash loading SD. I am thinkin g of a single chip micro with 2M flash and 512K sram, with no external chip s.

I can go to a store an get a 7" tablet with a dual core Allwinner, 512MB ra m, 4GB flash for 50$

if you buy parts and build something with a 7" lcd and capacitive touch yourself I'd think $50 is hard to meet, even with a single chip micro

-Lasse

com:

out of China. AllWinner stuff is 'less bad' than some of the other cheapo SoCs as far as software openness goes - that means there's a little more of an ecosystem about it. Such a tablet is basically a touchscreen, the AllW inner SoC, and maybe a wifi chip and battery. Beware of the batteries, the y may not be high quality - you could disconnect them if not needed. I'm a ssuming you'd want it rooted, so check there is root available.

oC still need two external SDRAM and external flash loading SD. I am think ing of a single chip micro with 2M flash and 512K sram, with no external ch ips.

ram, 4GB flash for 50$

Yes, economy of scale.

ourself I'd think $50 is hard to meet, even with a single chip micro

Doable for 10k pcs. You can get parts much cheaper than retail.