There are exemptions from FCC Part 15 requirements for several classes of
devices, including:

8.Digital devices in which both the highest frequency generated and the
highest frequency used are less than 1.705 MHz and which do not operate fro=
m
the AC power lines. Digital devices that include battery eliminators, AC
adaptors or battery chargers which permit operation while charging or that
connect to the AC power lines indirectly do not fall under this exemption.

Also,

Low-frequency devices that don't generate timing signals or pulses at a rat=
e
in excess of 9,000 pulses (cycles) per second (i.e., 9 kHz)

So, with a low enough clock rate, you can probably do without the
certification. However, note that even though certification is not required=
,
the FCC can still shut you down if your device interferes with others.

~ Bob Ammerman
RAm Systems

> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
Of
> Chris McSweeny
> Sent: Sunday, November 06, 2016 2:42 PM
> To: Microcontroller discussion list - Public. <piclist@mit.edu>
> Subject: Re: [EE] Really simple cutoff circuit
>=20
> On Sun, Nov 6, 2016 at 7:26 PM, Bob Blick <bobblick@outlook.com> wrote:
>=20
> > If it's a lithium-ion or lithium-polyester, how about using a 1-cell
> > protector chip specifically designed for it, like the CS213?
> >
>=20
> I was kind of thinking that - though the battery supposedly already has
one. He's
> sending me the bits and I'll do some testing - and I can prototype the
solution
> otherwise.
>=20
> If not one of those, then the 10F PIC is looking a good solution (though
as
> mentioned before I might go for an AtTiny10 simply due to better recent
> familiarity - I'm not sure I even have anything to programme a 10F). Is i=
t
> possible to use VCC as a reference and measure the value of the internal
> voltage reference against that (maybe by sending the reference voltage ou=
t
on
> a pin)? If not I'd surely need a voltage divider.
>=20
> I'm in the UK, but in any case these devices aren't going on sale - I'll
check if
> there are any regs I need to meet, but I don't think there would be - wil=
l
be
> used by a commercial company, but as part of kit they lease/loan out and
any
> arrangement with me certainly wouldn't involve me selling to them.
>=20
> Thanks for all the help,
>=20
> Chris
> --
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--=20
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