[Nut-upsuser] Building a Custom UPS with NUT Compatibility

[Charles Lepple]

Hi Josh,

I'm not finding this Microchip firmware example online at the moment, but there was once a PIC sample project that implemented USB HID PDC, which is the protocol the NUT usbhid-ups driver speaks. I think the OpenUPS product (somewhat misleadingly named IMHO; the firmware is not open source, as far as I know) has similar HID descriptors to that example project, and it is one of the models with custom variables.

https://networkupstools.org/docs/man/usbhid-ups.html

https://github.com/networkupstools/nut/blob/v2.8.0/drivers/openups-hid.c

As long as you have a good USB HID vendor example project to work from, you should be good to go. HID PDC is fairly straightforward, just with a lot of different names and variables. For basic system shutdown, there are just a few bits in UPS.PowerSummary.PresentStatus that need to be implemented.

Related: I haven't followed ESR's "upside" project in a while, so not sure if it will provide a good starting point. If nothing else, there might be some good UPS engineering information in the wiki: https://gitlab.com/esr/upside

-- 
Charles Lepple
clepple at gmail

> On Sep 16, 2022, at 3:34 PM, Joshua Quesenberry via Nut-upsuser <nut-upsuser at alioth-lists.debian.net> wrote:
> 
> Good Afternoon,
>  
> I’m part of team that’s been tasked with building an embedded system that does, among other things, battery management, including behaving like a UPS. We’d like to take full advantage of integrating with NUT and hopefully also it offers some support for running custom queries of the device? Can some point me in a good direction for writing firmware that works seamlessly with NUT? Are there any existing firmware frameworks that are open source that I can look at? We haven’t selected a microcontroller/microprocessor yet, but we’re familiar with Microchip and NXP, so if one of those would provide a shorter path to results or you have a 3rd recommendation to consider, please let me know.
>  
> Thanks!
>  
> Josh Q
>  
> 

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