On Sun, 19 Jan 2020 at 19:58, Dave VE3LHO <dave@...> wrote:
On Sat, Jan 18, 2020 at 09:28 PM, Jerry Gaffke wrote:
Indeed, the $2 Blue Pill has two 12bit A/D's, good to 1 msps, up to 16 channels.??
Unfortunately, the raw specs can be misleading. The issue, typically, is noise which causes the lower bits of the ADC result to be garbage.
There is a figure of merit for ADCs called Effective Number of Bits (ENOB). ENOB is basically how many bits you can rely on to actually represent the signal at the input to the ADC. Some people have measured ENOB for Blue Pills and found that there are fewer "effective" bits than on a typical 8b Atmel Arduino board. 7? or 8 as I recall where I think the Arduino boards being measured were 8 or 9.
The speculation is that the culprit on the Blue Pill boards is the poor layout and 2 layer board. Apparently, the original LeafLabs Maple boards which used the same ST32 micro had better ENOB.
