Re: Raspberry Pi SenseHAT / AstroPi

[slos <new.stephane.los@gmail.com>]

Le mardi 23 janvier 2018 18:40:16 UTC+1, Dmitry A. Kazakov a écrit :
> On 2018-01-23 16:45, slos wrote:
> 
> > To play with Raspberry Pi I have a SenseHAT, renamed from AstroPi, which is a HAT with some sensors :
> > https://www.raspberrypi.org/documentation/hardware/sense-hat
> > 
> > Since it was designed to go in space, I would have thought an Ada library to be available... ;-)
> > But I could not find one. :-(
> 
> Way too expensive and useless for automation purposes.
Well, I just wanted to play with some sensors and there are some on this SenseHat which costs by the way less than 40 Euros.
And connecting it to a PLC could be fun by allowing to control some process / machine like with a Wii Remote :
https://en.wikipedia.org/wiki/Wii_Remote
> There are 
> virtually thousands of different hats you cannot expect all of them 
> supported.
Of course since the HAT connector provides only signals like GPIO, I2C, SPI, UART, you can connect whatever you want to it. And of course you can design your own.
> 
> Anyway for [semi-]serious use one usually designs a new one. E.g. for a 
> BeagleBone board our partner designed a hat with many A/D converters and 
> a tiger chip.
This SenseHat is for discovering / fun / demo / what you can think of, and isn't that expensive. And one can just plug it on top and use the provided software to start playing.
> 
> The problem is that the architecture of ARM boards does not allow use of 
> modular components. A monolithic sensor/actuator board never has a 
> chance to meet the requirements, so one must design it new each time.
Or use one that fits with their needs.
> 
> > So what can be found is a Python library on top of a C++ one.
> 
> Actually I would expect a proper driver. A C library means it must run 
> with root privileges. Not good.
Why would you need root privileges to run a C library ?
You have to set the proper rights to a user or group and that should suffice.
> 
> > But maybe I have missed something already done in Ada ?
> 
> What for? If you say that there is a C library, you can call it directly 
> from Ada.
No, I said there is a C++ library and a Python binding on top.
Actually the Python library uses the C++ library for some sensors and devices directly for joystick and framebuffer.
> 
> P.S. We could consider supporting it in our middleware, but as I said, 
> at first glance it looks too expensive and much useless.
It could allow some people interested in Ada language to play on an inexpensive target. Is it useless ?
The Raspberry Pi was designed exactly for that purpose. Teaching and experiments for anyone interested in.
> Then it does 
> not scale other architectures. We usually support boards / protocols 
> available for more that just Raspberry Pi. Raspberry Pi has a very bad 
> call among customers. One can show it as proof of the concept but 
> nothing more.
> 
> -- 
> Regards,
> Dmitry A. Kazakov
> http://www.dmitry-kazakov.de
Stéphane