Theo wrote on 12/19/2017 7:32 PM:
> rickman  wrote:
>> I would be writing my own programs using Gforth.  It would be talking to
>> external devices and, as I've said, using the phone for the UI.  The phone
>> will do data collection, status display and perform whatever calculations
>> are needed to support that.  It might also do data logging.  Nothing
>> complex so not demanding of the software on the phone.  I'm thinking for
>> $50 it is cheaper than a tablet or a pi with attached display and keypad
>> and a *lot* more flexible.
>
> Surprisingly, there does appear to be gforth for Android:
> https://wiki.forth-ev.de/doku.php/en:projects:gforth-android:start

Why surprisingly?  I've downloaded it but not done anything with it yet.


> However I'm not sure how well it will play with the phone UI - does it use
> the Android widgets or do you have to build all of that yourself?
>
> Otherwise I'd suggest implementing your control logic on, say, a Pi and
> having the tablet talk to it via wifi - simplest would be a web interface.
> Any tablet you buy will have a web browser so you can treat them as
> completely interchangeable.  The Pi running the control logic and web server
> is where the application does most of its work and talks to whatever
> hardware you need.

Why is a pi needed at all?  I don't follow.


> You might get away with a more basic microcontroller instead of a Pi, but
> running a wifi/TLS/etc stack on those is a bit of a pain.  Maybe an ESP8266
> would suffice, but it's quite limited especially when doing TLS.

Wow!  I remember years ago, back when trade magazines were paper, an article
talked about how much MCUs were shrinking and that we may have Linux on a
chip at some point.  That is essentially what a pi is.  But running a
non-realtime OS is not the way to go when doing low level hardware I/O.
It's ok to play with the pi and make things go ding and flash lights, but a
tiny MCU is much more appropriate for most things.  I'm pretty sure I
mentioned that previously.  The sensor will have an MCU and communicate with
the phone via bluetooth as long as it is reliable.  I've had trouble with
bluetooth on every PC I've ever had.  But it seems to work ok phone to
earpiece anyway.

I also read that phones can have TTL level serial ports on the USB
connector, so that might be an option as well.


> You could go Bluetooth or USB device instead, but the downside is there's
> more risk it will be incompatible with future tablets in some way.

Why?  Use of standard interfaces seem like the low risk approach to me.

--

Rick C

Viewed the eclipse at Wintercrest Farms,
on the centerline of totality since 1998

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