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A low-cost Windows 8 tablet for digital modes SOTA operations

I found this on the Southgate A.R.S. News site. It looks like it would have great potential for getting on to PSK31 and other digital modes from the hill-top!

73,
Walt (G3NYY)

Sorry dupe… you are already in the log… :smile:

I’ve read the various posts, including the Southgate ‘news’ posts, but none seem to meet my criteria as yet.

I understand the want for cheap, who doesn’t? But then there’s the need for practicality.

I would like to be able to charge a device whilst using it and to be able to interface to external ‘things’ as well. I’d even say that I would pay a bit more for such luxuries…

Windows tablets are all well and good, but I struggle against, rather than with, my Windows PC to the point where Linux begins to become attractive. I’ve avoided iOS systems and used Android but that has its downsides as well.

Maybe I need to revisit my Raspberry Pi and Aruinio boards and try, again, to get to grips with programming language?

Oooh! And there was me thinking your posting was about cut-price indigestion tablets!
:wink:

73,
Wlat

Well Apple have sold around 200million premium priced iPads, I don’t know how many Android (premium or cheap) tablets have been sold. If there was ANY demand for a tablet that could drive something and be charged simultaneously then you’d be able to buy one. The USB battery charging spec allows it… oh how I remember the fun implementing a simulation for one of our customer’s cellphone SoCs that did USB2 OTG with full support for CDP, DCP and ACA etc. The phrase to look for is ACA (Auxilliary Charging Adapter), it allows for an OTG device to charge itself whilst acting as a USB host.

Anyway a tablet is not a replacement for a desktop/laptop computer… it’s an adjunct that is primarily as a media consumption device. You browse the web, send emails and watch films etc. They have fast sleep/wakeup times and probably the longest they get run for continuously is when you watch a film or read a book on one. So there simply isn’t a mass market use case for device connection and charge simultaneously.

This Windows tablet is a little lightweight on the battery life at 4-6hours (lets plump for 4hrs and be happy if it goes longer) when premium Andriod/iOS devices are in the 8-10hrs range. How much is an iPad mini in comparison? So for the price the battery life is acceptable for the price!

Ah well, so I’m in a minority again. That’s not unusual.

Arduino, blah ! Only ever for convenience - but never to learn. It WILL teach you some bad habits in embedded C that are hard to shake off.

Jonathan.

1 Like

What is:

SoC
OTG
CDP
DCP
?

73,
Walt (G3NYY)

SoC: system on a chip… all the individual building blocks of a system implemented on one piece of Silicon instead of lots of separate integrated circuits soldered to a circuit board.

OTG: On-the-go. A special kind of USB port. By default USB ports are either a host or a device. A laptop USB port will be a USB host, the host controls devices plugged into it. A USB device is an item that is controlled by a USB host. A USB mouse is a device, a USB memory stick is a device, a 3g dongle is a device. You can only connect a host to a device, never a host to host or device to device. An OTG device defaults to being a USB device but when connected to another device, they decide one of them will become a host.

A USB printer is a device, the computer you connect it to controls the printer. A camera with USB interface is a device, you connect it to a host and the host can transfer the images to and from the camera. An OTG printer would act as a device with a host computer but when connected to a device will become a host allowing you to connect a camera direct to a printer and print the images from the camera without using a computer to control them.

CDP: Charging downstream port. A computer’s USB port is normally SDP: Standard Downstream Port. It can control devices connected to it and will allow up to 500mA to be drawn from its power rails to power a USB device. A CDP is exactly the same but allows upto 2A to be drawn. You can charge a phone/tablet from an SDP but it will be much slower than using a CDP.

DCP: A dedicated charging port. This is a powersupply with a USB connector that typically provides 1A to 2A.

When you plug USB items together, all sorts of signalling occurs during what is called enumeration. This is when your computer decides how much current to allow, finds drivers for the device, allocates a drive letter for USB sticks etc. The USB battery charging specs allow USB charging aware devices to twiddle the signal levels to marginal voltage levels. The voltages are small enough that they look like digital 0 levels and so no data is transferred but big enough that the USB chips can decide what the port is. i.e. SDP, CDP, DCP etc.

A USB host provides 5V at 500ma…2A. A USB device can power itself from this power. If you have an OTG device like a tablet then when you connect it to a PC, the computer USB host provides power to charge the tablet battery, the computer USB host negotiates with the tablet and typically the tablet looks like a USB memory stick so that you can trasnfer files to and from the tablet. As all tablets are OTG, if you connect a USB memory stick to the tablet (with an OTG adapter cable) then tablet becomes the host and it provides 5V (at some current) to power the USB memory stick. The contents of the USB stick are visible on the tablet. However, now the tablet is providing power for the USB stick you cannot charge the tablet battery. You need an ACA, auxilliary chariging adapter that plugs between the OTG tablet and the USB stick so that it provides power for the tablet and the USB stick. That way you can charge the battery and power the sick. Typically you connect a DCP to an ACA to power the OTG :smile:

Clear now?

2 Likes

OMG!

(“Body is invalid try to be more descriptive” Mr. Reflector said"):grin:

Oh there is so much more and that is just battery charging.

e.g. your phone battery is completely discharged and it will not power up. You plug it into your PC to charge it. The PC doesn’t know what it is because the phone can’t boot and complete the enumeration. The USB spec allows a device to pull a maximum of 100mA when it has not enumerated. This means your phone can pull 100mA and it starts to charge its battery as best it can. Within 10mins it must be capable of booting enough of the phone software so that it can enumarate with the PC and request more current. At this point it can go back to deep sleep so that the battery charges. Later it can wake up and use the power from USB to run the phone and charge the battery.

Then we have the physical signalling for USB 1.0/2.0/3.0/3.1. Then the USB specs for exchanges acros the bus. And the OTG spec. Then we have the software that runs on top of the USB exchanges. My employer’s USB3.0 hardware data manual runs to 1884 A4 pages of text and diagrams on the registers and how to program the chip to do USB.

There’s an awful lot going on in USB!

“My brain 'urts!”

Brian

1 Like

Amazing!
It’s a jungle of acronisms and so many features and specs we, the mortals, don’t even guess about their existance…
Perhaps it will be easy for you to say why my laptop is not anymore recognising the SD cards when entered into its slot.
I always thought it might have lost the driver but after reading your last post, I fear it may well be anything else… :wink:
Best 73 de Guru - EA2IF

Thank you very much, Andy! Most informative.

73,
Walt (G3NYY)

I now have one, so will report relevant info in due course. It will download and run Thunderbird and HDSDR, so looks promising.
73,
Rod

SDR# is meant to work OK

Hi Rod,
It would interest me to know if your Windows tablet is Intel processor based and hence able to run most if not all Windows desktop PC programs or whether it is using a different (e.g. ARM) processor and hence only able to run applications written for the Windows mobile platform?

I have used my 7" ASUS MemoPad Android tablet from a couple of summits, trying to get a PSK31 contact but even the size and weight of a 7" tablet has to be weighed up against to results one can get.

By the way Wolphi does a whole range of amateur radio “apps” for Android phones and tablets, these interface to the rig via the headset 3.5mm connector (note many tablets don’t have mic-in wired to the 3.5mm jack - the ASUS tablet goes and all phones do). Wolphi also does a physical interface for FT-8xx and IC-703/6 to Android 3.5mm audio jack - or you can make your own - he publishes the circuit for free.
http://www.wolphi.com/

73 Ed.

The full technical details are in the linked article in the 1st post.

Ok, so it’s running the 1.33GHz Intel Atom processor - a quad-core upgrade of the processor family previously used in Netbooks, which as it says means it can run programs written for the desktop (as long as they don’t need too much “horse power”). Interesting that the 8 inch version starts at around 80 pounds just 5 pounds more than the 7 inch version - that could be the “sweet spot”. The 10 inch versions start at about 140 pounds.

73 Ed.

Knock yourself out picking a cheap tablet!

http://www.banggood.com/Wholesale-Windows-Tablet-c-1835.html

Set country and currency at the top, the price doesn’t include local taxes/duty so you may have to pay a chunk extra. Or maybe not if you are lucky.