Date: Sun, 31 May 2020 11:11:40 -0600 From: Ian Lepore <ian@freebsd.org> To: "Dr. Rolf Jansen" <freebsd@cyclaero.com>, freebsd-arm@freebsd.org Subject: Re: BeagleBone AI Message-ID: <966c33ea1924c2cfab5d9e295a9239d134e03f8a.camel@freebsd.org> In-Reply-To: <DCF67826-C2CA-461F-9A61-F934F6FB042A@cyclaero.com> References: <DCF67826-C2CA-461F-9A61-F934F6FB042A@cyclaero.com>
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On Fri, 2020-05-29 at 23:21 -0300, Dr. Rolf Jansen wrote: > We are starting a new project of industrial device controllers. We > want to utilize ARM-SBCs as unit controllers (and here a unit is one > industrial device), and we need to attach at least 24 ADCs, 8 DACs > and 16 DIOs to each unit controller (UC). Many unit controllers > (eventually tenths to hundreds) would then communicate by a custom > protocol over ethernet with a command and control server. The UCs and > the C&C server would be operated by FreeBSD. Direct interoperability > of the UCs with 3rd party IT systems is not a concern, integration > needs to be done via the C&C server. > > Since the sample/update rate requirements are quite low, we are going > the I²C path, and initial testing has been done using the BeagleBone > Black. It got 2 separate I²C 400 kbit/s busses which helps already, > avoiding I²C address conflicts. Yet, the 8 port I²C switch TCA9548A > is working very well, and we are now sure to be able to attach enough > ADCs, DACs and DIOs to each unit controller. > > Although the initial viability tests were done with a BeagleBone > Black running FreeBSD 13-CURRENT, we could start with another more > modern SBC. > > First Question: > > What modern SBC with more than 1 I²C bus and which can run FreeBSD > 13++ would you suggest? > > > Now recently, I found the BeagleBone AI site > https://beagleboard.org/ai/ <https://beagleboard.org/ai/>. This one > got also 2 I²C busses, and physically, with respect to a housing, it > could be a 1:1 replacement for a BBB. It seems, this one is still too > new for FreeBSD. I am very fond of the BB concept - for me it is much > more appealing for industrial embedded applications than for example > any RPI. However, the BBB came to age, and I would start a new > project with it only, if there would be a reasonable chance for an > upgrade path. > > Two more Questions: > > Is it reasonable to assume that FreeBSD would run on a BBAI in the > future, let¢s say in 2 to 3 years? > > Perhaps I could help porting FreeBSD to a BBAI. What would be the > general steps? > > > Many thanks in advance for any suggestions, advices and > clarifications. > > Best regards > > Rolf > BTW, if you need drivers for any new i2c devices just let me know and I'll see what I can do. Also, in my experience you can often get away with running an i2c bus faster than 400khz if you need more bandwidth. I've never seen any modern chip fail to work at 800khz, and most seem to work fine up to about 1mhz; above that they become pretty unreliable. -- Ian
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