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'F427 ADC channel 16 (temperature sensor)

The 'F427 (437/429/439 "BigManta") is pretty much completely backward compatible, meaning, that a reasonably well written 'F405/407 program (i.e. which does not touch the bits reserved in 'F405/407) binary will run unmodified in the 'F427.

There are two little exceptions I know of, both in ADC: the VBAT divider is 4 rather than 2, and the temperature sensor is on channel 18 rather than on channel 16 (it shares ch.18 with the VBAT measurement, but there are register bits which switch on/off the internal switches in an unambiguous way).

I am currently working on a 'F407 program, but have for some reasons a 'F427 on the prototype board. Today, I've linked in an older, already existing 'F407 piece of code which measures and displays both VBAT and temperature. It displayed VBAT as 1.51V and I immediately realized what's wrong - the /3 divider in 'F427 instead of /2 - but waitaminute... a correct temperature is displayed!

So I played a bit and found, that channels 16 and 18 read basically identically, when the temperature sensor is activated.

This is non-fatal, but I would really like to hear ST to comment.

JW

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