Dennis,

> The odds are very good that all pins on the module map directly
> to the same pin of the HC-05 chip itself... And most likely the chip
> specification sheet will use the same name.

No such luck I'm afraid.   I'm looking at the HC-05 datasheet here :

https://components101.com/sites/default/files/component_datasheet/HC-05%20Datas
heet.pdf

No EN or STATUS pins.  Heck, not even RXD and TXD are present as such. :-)

> Now -- if they are buffered/inverted between the module pins
> and chip should be in the documentation from the module
> manufacturer.

That is documentation I expected to come with the module, but didn't.   And
with the absense of an actual product number (other than the webstores
internal one) there is no way to get at it.

> (Let me guess, you went lowest bid on eBay for this)

Nope.   I ordered it thru a webshop in my own (small) country.  Pretty-much
to forgo the kind of horror stories you sometimes read about ordering
abroad.  Alas, It looks like I fell into another pit.

>
https://www.instructables.com/community/Are-the-JY-MCU-and-the-HC-05-bluetooth-
module-the-/
> implies the module has voltage converters for 5V I/O.

That would clash with the "LEVEL : 3.3V" silk-screen info on the back of my
module (directly next to the RXD and TXD pins) - which makes me yearn for
the breakout boards manufacturer specs.

> The schematic diagram shows a Maxim MAX3232 chip

I'm afraid that that schematic (in the same image as the module) is just a
tad too blurred to be able to read any text there.   Heck, can't even see
what the two words at either end of that diode say (and I've even scaled up
the 1000x1000 "hires" image to try)

> Note that both of those conflict with the bottom labeling on this
> module, which states 3.3V levels for RXD and TXD.

Yup.  Conflicting/mismatching info that I've also found during my searches.
Which either means someone (a hobbyist ?) cut corners, or is possibly
targetting a different module ...

> At this point, I'd probably pull out an oscilloscope and put that
> on the output pin&ground, then apply first 3.3V to the module,
> followed by 5V

I was thinking of using an ohm meter to figure out where the breakout board
pins lead to (directly connected to the HC05 module or thru something), but
your idea doesn't sound half bad either. :-)

Though its definitily /not/ something I expected to need to do.   I will
probably refrain from buying more, as I would likely need to go thru the
whole song-and-dance again. :-(

Regards,
Rudy Wieser

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