[Nut-upsuser] Generic UPS driver

[Charles Lepple]

On Dec 21, 2013, at 11:36 PM, Ariel Wainer wrote:

> On 21/12/13 21:31, Ariel Wainer wrote:
>> 
>> Ok, I did this, here is how it went (approximately):
>> t=0     power on the UPS, with some load.
>> t=2 min unplug the UPS from mains, alarm goes off.
>> t=33 min low battery alarm goes off.
>> t=35 min ups powers down.
>> 
> 
> Ok, trying to make sense of the capture (again: it's all guessing, I
> have no experience with usb protocol):
> 
> Up until packet #255/131 seconds  in the pcap file, the payload is 0x03,
> then  it changes to 0x01 , and then it changes again to 0x02 at  packet
> #3975/2081 seconds.
> 
> It seems like:
> 0x01 = AC failed
> 0x02 = Battery low.
> 0x03 = AC is ok

Also, there is an Interrupt Out transfer at #4115/2154 (repeated at #4117) that sends a 0x01 down to the UPS. I assume it turns off at that point, or shortly thereafter?

> It looks simillar to the UPS implementation example from
> http://www.usb.org/developers/devclass_docs/pdcv10.pdf

Well... the first few pages of Appendix A are boilerplate USB descriptors. The report descriptor (A.6) is where things start to differ. Your UPS doesn't have Usage Page 0x84, 0x85 or 0x86 in its report descriptor - it only has 0xFFA0, which is in the vendor-specific range, and the two Usage fields are just 8-byte unstructured buffers (also with vendor-specific IDs).

It might be possible to tell usbhid-ups to match on the 0xFFA0 usage page, and ignore all of the other HID PDC definitions. I'll poke around the code.

-- 
Charles Lepple
clepple at gmail