[Arm-netbook] EOMA68 laptop battery management.

Luke Kenneth Casson Leighton lkcl at lkcl.net
Wed Mar 2 23:10:18 GMT 2016

On Wed, Mar 2, 2016 at 10:49 PM, Jakub Kákona <kaklik at mlab.cz> wrote:
> Thanks for the diagram!

 no problem.

> But I have one more question. Is it really necessarily to operate bq24193's
> I²C bus at 1.8V?

 i don't know! :)

> According to datasheet http://www.ti.com/lit/ds/symlink/bq24193.pdf
> The 1.8V was used only as example of operating voltage..
> The Absolute Maximum Ratings for all SDA, SCL and INT pins is 7V and both
> are "i2c standard open collectors" and could be pulled-up to any rail within
> the operating voltage range..
> Therefore I think the Voltage translator is not necessary...

  if you reckon an STM32F072 could handle it, then fine.  that saves
at least 2 ICs, which is great.  if you'd like to actually test it,
STM32F072-NUCLEO boards are only $EUR 10 from rs-online, mouser, arrow
and digikey.

 ok, so key question: what sort of timescale do you think you'd be
able to do this in?  reason i ask is, i need to work out the timeline.

 practical matters: i used eurocircuits to get the PCBs done, they
were about 7-10 days (unless you pay extra), and around $EUR 70 for
QTY2.  i have some components (connectors, switches, capacitors) i can
send you.

 more practical matters: from mid-april i'm going to be moving to a
new country *every month* until the end of the year, to track getting
this into a first production run.


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