The process of debugging my remote oil level sensor continues. This is
based on a PICO W plus a nano timer to wake it up every couple of hours
to send a message via the home wifi.

After an issue in which it stayed woke, and flattened its battery and
never sent any data, the code has been modified and its back on the tank
after extensive testing, with three *lithium* batteries.

I was unaware of lithium primary cells in an AA format till now. But
three of these start out at 5,2V and stick around 5V for a long time.
Perfect for the unit.

In addition they are reckoned to be more tolerant of the cold and to
last twice as long.

Early days, but if anyone is thinking of battery powering a PICO outside
for intermittent use, a nano timer and lithium primary cells looks to
be the best technology.


--
Any fool can believe in principles - and most of them do!



--- PyGate Linux v1.5.16
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

The Natural Philosopher <tnp@invalid.invalid> writes:

On 15/06/2026 19:49, Brian Gregory wrote:

nano timer ??
What's that then?

TPL5100

https://www.ti.com/product/TPL5110

I kinda thought modern microcontrollers have this sort of thing built
in? Oh, looks like the Pico (no W) draws 2 mA in "deep sleep" and this
timer draws 35 nA.

--- PyGate Linux v1.5.18
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 24/06/2026 07:33, Anssi Saari wrote:

The Natural Philosopher <tnp@invalid.invalid> writes:

On 15/06/2026 19:49, Brian Gregory wrote:

nano timer ??
What's that then?

TPL5100

https://www.ti.com/product/TPL5110

I kinda thought modern microcontrollers have this sort of thing built
in? Oh, looks like the Pico (no W) draws 2 mA in "deep sleep" and this
timer draws 35 nA.

Yes.

Plus there is the advantage that you get a complete reboot every time
things fire up.

And its very very simple. Drive pico pin high. get power cut.


--
Canada is all right really, though not for the whole weekend.

"Saki"


--- PyGate Linux v1.5.18
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

Anssi Saari <anssi.saari@usenet.mail.kapsi.fi> wrote:

The Natural Philosopher <tnp@invalid.invalid> writes:

On 15/06/2026 19:49, Brian Gregory wrote:

nano timer ??
What's that then?

TPL5100

https://www.ti.com/product/TPL5110

I kinda thought modern microcontrollers have this sort of thing built
in? Oh, looks like the Pico (no W) draws 2 mA in "deep sleep" and this
timer draws 35 nA.

That does sound surprisingly bad for the Pico. Seems that the RP2040 is
0.18mA in 'dormant' (ie deep sleep) and 0.38mA in 'sleep', which is a bit better. So must be something else on the Pico that's not so good in sleep mode.

If you've got other stuff hung off the MCU that isn't super low power,
you're going to have to power-gate it anyway, in which case the nano timer
will do that at the same time.

Theo

--- PyGate Linux v1.5.18
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 24/06/2026 13:41, Theo wrote:

Anssi Saari <anssi.saari@usenet.mail.kapsi.fi> wrote:

The Natural Philosopher <tnp@invalid.invalid> writes:

On 15/06/2026 19:49, Brian Gregory wrote:

nano timer ??
What's that then?

TPL5100

https://www.ti.com/product/TPL5110

I kinda thought modern microcontrollers have this sort of thing built
in? Oh, looks like the Pico (no W) draws 2 mA in "deep sleep" and this
timer draws 35 nA.

That does sound surprisingly bad for the Pico. Seems that the RP2040 is 0.18mA in 'dormant' (ie deep sleep) and 0.38mA in 'sleep', which is a bit better. So must be something else on the Pico that's not so good in sleep mode.

The broadcomm wifi chip.

If you've got other stuff hung off the MCU that isn't super low power,
you're going to have to power-gate it anyway, in which case the nano timer will do that at the same time.

Indeed. I have an ultrasonic unit.

I looked at every combination I could think of, and ended up with the
nano timer after trying to construct my own in analogue.

I can say that the three lithium primary cells plus the nano timer (MUST
have a BIG electrolytic on its back end or it goes unstable) is THE very
best way to have a periodic remote sensor 'phone home' if a cable can't
be laid



--
I would rather have questions that cannot be answered...
...than to have answers that cannot be questioned

Richard Feynman




--- PyGate Linux v1.5.18
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

Theo <theom+news@chiark.greenend.org.uk> wrote:

Anssi Saari <anssi.saari@usenet.mail.kapsi.fi> wrote:

The Natural Philosopher <tnp@invalid.invalid> writes:

On 15/06/2026 19:49, Brian Gregory wrote:

nano timer ??
What's that then?

TPL5100

https://www.ti.com/product/TPL5110

I kinda thought modern microcontrollers have this sort of thing built
in? Oh, looks like the Pico (no W) draws 2 mA in "deep sleep" and this
timer draws 35 nA.

That does sound surprisingly bad for the Pico. Seems that the RP2040 is >0.18mA in 'dormant' (ie deep sleep) and 0.38mA in 'sleep', which is a bit >better. So must be something else on the Pico that's not so good in sleep >mode.

I think (ultra) low power was not a primary design goal for the Pico.

--
Dipl.-Inform(FH) Peter Heitzer, peter.heitzer@rz.uni-regensburg.de

--- PyGate Linux v1.5.18
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 24/06/2026 15:51, Peter Heitzer wrote:

Theo <theom+news@chiark.greenend.org.uk> wrote:

Anssi Saari <anssi.saari@usenet.mail.kapsi.fi> wrote:

The Natural Philosopher <tnp@invalid.invalid> writes:

On 15/06/2026 19:49, Brian Gregory wrote:

nano timer ??
What's that then?

TPL5100

https://www.ti.com/product/TPL5110

I kinda thought modern microcontrollers have this sort of thing built
in? Oh, looks like the Pico (no W) draws 2 mA in "deep sleep" and this
timer draws 35 nA.

That does sound surprisingly bad for the Pico. Seems that the RP2040 is
0.18mA in 'dormant' (ie deep sleep) and 0.38mA in 'sleep', which is a bit
better. So must be something else on the Pico that's not so good in sleep >> mode.

I think (ultra) low power was not a primary design goal for the Pico.

I think that is very true. What attracted me was the amount of flash,
and ram, the availability of wireless and ADCs and the price. Less than
a pint of beer in a nightclub.
Arduinos were 3 times the price

The ZeroW running debian is a damn sight easier to code for, however.

--
?There are two ways to be fooled. One is to believe what isn?t true; the
other is to refuse to believe what is true.?

?Soren Kierkegaard


--- PyGate Linux v1.5.18
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 25/06/2026 04:35, wmartin wrote:

On 6/24/26 08:41, The Natural Philosopher wrote:

On 24/06/2026 15:51, Peter Heitzer wrote:

Theo <theom+news@chiark.greenend.org.uk> wrote:

Anssi Saari <anssi.saari@usenet.mail.kapsi.fi> wrote:

The Natural Philosopher <tnp@invalid.invalid> writes:

On 15/06/2026 19:49, Brian Gregory wrote:

nano timer ??
What's that then?

TPL5100

https://www.ti.com/product/TPL5110

I kinda thought modern microcontrollers have this sort of thing built >>>>> in? Oh, looks like the Pico (no W) draws 2 mA in "deep sleep" and this >>>>> timer draws 35 nA.

That does sound surprisingly bad for the Pico.ÿ Seems that the
RP2040 is
0.18mA in 'dormant' (ie deep sleep) and 0.38mA in 'sleep', which is
a bit
better.ÿ So must be something else on the Pico that's not so good in
sleep
mode.

I think (ultra) low power was not a primary design goal for the Pico.

I think that is very true. What attracted me was the amount of flash,
and ram, the availability of wireless and ADCs and the price. Less
than a pint of beer in a nightclub.
Arduinos were 3 times the price

The ZeroW running debian is a damn sight easier to code for, however.

Be careful about trusting that ADC, it is somewhat notorious for inconsistent lower bits...summing and averaging helps, if you have the inter-sample time to do that.

The errors are very predictable as they are caused by certain
very low value capacitors in the switched capacitor adc having
incorrect values. It seems that the chip design tools did not
model stray or fringing capacitances accurately enough.
There is software around that can post process the adc readings
to make a substantial improvement. https://github.com/kitanokitsune/rp2040adc_correction
John


--- PyGate Linux v1.5.18
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 25/06/2026 04:35, wmartin wrote:

On 6/24/26 08:41, The Natural Philosopher wrote:

On 24/06/2026 15:51, Peter Heitzer wrote:

Theo <theom+news@chiark.greenend.org.uk> wrote:

Anssi Saari <anssi.saari@usenet.mail.kapsi.fi> wrote:

The Natural Philosopher <tnp@invalid.invalid> writes:

On 15/06/2026 19:49, Brian Gregory wrote:

nano timer ??
What's that then?

TPL5100

https://www.ti.com/product/TPL5110

I kinda thought modern microcontrollers have this sort of thing built >>>>> in? Oh, looks like the Pico (no W) draws 2 mA in "deep sleep" and this >>>>> timer draws 35 nA.

That does sound surprisingly bad for the Pico.ÿ Seems that the
RP2040 is
0.18mA in 'dormant' (ie deep sleep) and 0.38mA in 'sleep', which is
a bit
better.ÿ So must be something else on the Pico that's not so good in
sleep
mode.

I think (ultra) low power was not a primary design goal for the Pico.

I think that is very true. What attracted me was the amount of flash,
and ram, the availability of wireless and ADCs and the price. Less
than a pint of beer in a nightclub.
Arduinos were 3 times the price

The ZeroW running debian is a damn sight easier to code for, however.

Be careful about trusting that ADC, it is somewhat notorious for inconsistent lower bits...summing and averaging helps, if you have the inter-sample time to do that.

Oh yes. It has noise allright. But feeding sensors from the stabilised
3.3v line helps a lot.

Do I really need 12 bit accuracy to measure temperature? Not really. Nor
is it a microsecond sample that I need, Ring buffers and averages are
easy to implement


Onboard is fine.

--
The difference bweteen a psychopath and a saint is that the psychpoath
takes what he can and gives only what he must, but the saint gives
everything he can and takes only what he needs.




--- PyGate Linux v1.5.18
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On 6/24/26 08:41, The Natural Philosopher wrote:

On 24/06/2026 15:51, Peter Heitzer wrote:

Theo <theom+news@chiark.greenend.org.uk> wrote:

Anssi Saari <anssi.saari@usenet.mail.kapsi.fi> wrote:

The Natural Philosopher <tnp@invalid.invalid> writes:

On 15/06/2026 19:49, Brian Gregory wrote:

nano timer ??
What's that then?

TPL5100

https://www.ti.com/product/TPL5110

I kinda thought modern microcontrollers have this sort of thing built
in? Oh, looks like the Pico (no W) draws 2 mA in "deep sleep" and this >>>> timer draws 35 nA.

That does sound surprisingly bad for the Pico.ÿ Seems that the RP2040 is >>> 0.18mA in 'dormant' (ie deep sleep) and 0.38mA in 'sleep', which is a
bit
better.ÿ So must be something else on the Pico that's not so good in
sleep
mode.

I think (ultra) low power was not a primary design goal for the Pico.

I think that is very true. What attracted me was the amount of flash,
and ram, the availability of wireless and ADCs and the price. Less than
a pint of beer in a nightclub.
Arduinos were 3 times the price

The ZeroW running debian is a damn sight easier to code for, however.

Be careful about trusting that ADC, it is somewhat notorious for
inconsistent lower bits...summing and averaging helps, if you have the inter-sample time to do that.


--- PyGate Linux v1.5.18
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)