On Sun, May 05, 2024 at 08:46:02PM +0100, Jonathan Cameron wrote: > On Tue, 30 Apr 2024 18:21:01 +0100 > Conor Dooley <conor@xxxxxxxxxx> wrote: > > > On Tue, Apr 30, 2024 at 07:29:45PM +0300, Alisa-Dariana Roman wrote: > > > + diff-channels: > > > + description: > > > + Both inputs can be connected to pins AIN1 to AIN16 by choosing the > > > + appropriate value from 1 to 16. > > > + items: > > > + minimum: 1 > > > + maximum: 16 > > > + > > > + single-channel: > > > + description: > > > + Positive input can be connected to pins AIN1 to AIN16 by choosing the > > > + appropriate value from 1 to 16. Negative input is connected to AINCOM. > > > + items: > > > + minimum: 1 > > > + maximum: 16 > > > > Up to 16 differential channels and 16 single-ended channels, but only 16 > > pins? Would the number of differential channels not max out at 8? > > May not really be limited to 16 differential. Many chips use general purpose > muxes on both sides so you can do all combinations. In practice that's normally > pointless. > > A more useful case is to do all but one channel as positive inputs and the remaining > channel as the negative for those 15 differential channels. Yah, 15 is what I had in my head as the highest reasonable number given the information given about the AIN# pins. > This is effectively the same as doing pseudo differential channels, but > on more flexible hardware. This is in contrast to a device that only supports > pseudo differential where there is a special pin for the negative > (this device has that as well as full muxes on the other 16 lines). > > Having said all that. The ad7194 datasheet says 8 differential channels.. > I have no idea why though... Maybe something to do with the mux switching? > Or maybe assumption is that if you want to do pseudo differential you'll use > the pseudo differential mode rather than wasting hardware? I didn't look at the datasheet tbf, I was just asking given the description didn't make sense to me and looking for an explanation from the author.
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