[Nut-upsuser] Protocol for an Arduino based UPS

[Glenn Ramsey]

Thanks Charles,

On 20/08/18 13:55, Charles Lepple wrote:
> On Aug 19, 2018, at 3:31 PM, Glenn Ramsey <gr at componic.co.nz> wrote:
>> 
>> Hi,
>> 
>> I'm building a DIY UPS for a Raspberry Pi using a 12V SLA battery, charger,
>> and an off the shelf 5V regulator. To monitor the battery level I'd like to
>> use an Arduino or similar type device. Since the Arduino can have a serial
>> over USB connection with the Pi I'd like to implement a protocol that can
>> be used with NUT.
>> 
>> Does anyone know if something like this has already been done? The only
>> thing I could find was this [1], but it doesn't look like there is a NUT
>> driver. Maybe I'm not searching with the right terms?
> 
> I'm at a loss for the right search terms, and I know we had someone
> considering building a USB/HID version of what you are talking about. If
> there was indeed another discussion, it would probably be on the nut-upsdev
> lists:
> 
> https://alioth-lists.debian.net/cgi-bin/mailman/listinfo/nut-upsdev

I found a post there from 2010:

https://alioth-lists.debian.net/pipermail/nut-upsdev/2010-April/004740.html

that describes what I want.

> A related UPS project (but I think they ruled out Arduino-class processors
> early): https://gitlab.com/esr/upside/wikis/external-interface
> 
>> 
>> If I were implement a UPS protocol what would be the easiest one to
>> implement that is already supported by NUT?
> 
> The Megatec/Q* protocols are fairly ubiquitous, so that might be where I
> would start.
> 
> You mentioned serial-over-USB - does the Arduino show up as a /dev/ttyUSB*
> node or similar on the Pi? The following assumes that it does.
> 
> blazer_ser has some test strings:
> 
> https://github.com/networkupstools/nut/blob/v2.7.4/drivers/blazer_ser.c#L73
> 
> but development has been moved to nutdrv_qx, which is the preferred driver to
> test against (though it is a bit more comprehensive, and perhaps less clear
> at first glance).
> 
> Protocol documentation: https://networkupstools.org/protocols/megatec.html

Thanks very much for that. That lead me to find this:

https://github.com/xm381/Raspberry-Pi-UPS

which appears to be exactly what I was looking for.

Glenn