[...] > > >> > > >> I think it is nicer to have it set in the dt; we need the dt anyway so > > >> it seems logical to get it setting the right channel. > > > > > > Can you please elaborate why is it logical? > > > > > > I took a brief look over the datasheet [1], here are the facts I see > > > (correct me if I'm wrong). I first looked at Figure 51. : > > > > > > - ADS1246 has two input channels > > > - ADS1247 has four input channels > > > - ADS1428 has eight input channels > > > > > > - Each one of the 2/4/8 input channels can be connected to either P(+) > > > or N(-) of the amplifier (figure 53) for the ADC. > > > > > > - Apparently, according to Figure 51. , it is possible to have only one > > > P and one N channel enabled at time (and therefore sample only one > > > pair of channels with the ADC) since the P and N rails are shared by > > > all the inputs and there's only one ADC block. > > > > > > Therefore, the userland would have to export sysfs file for each of the > > > channels where one would write if the channel is possitive(+) / > > > negative(-) / not_connected(NC) and then trigger the start of sampling. > > > > > > What do you think? > > > > This does not make them act as differential against each other. > > > > We can have several combinations as: > > > > 0 - P / 1 - N (differential) > > 0 - P / 1 - P / 2 - P / 3 - N (all differential to 3) > > and so on. > > > > So how userland would tell which would be the differential to use? > > > > Our board has: > > > > 0 against 1 > > 2 against 3 > > > > but it is a design choice. > > > > Am I missing something? > > echo 'P' > /sys/.../chan_mux_0 > echo 'P' > /sys/.../chan_mux_2 > echo 'N' > /sys/.../chan_mux_1 > echo 'N' > /sys/.../chan_mux_3 > > Like this for example ;-) And this could be nicely implemented via IIO, but > I believe there might even already be an IIO API for this stuff. btw. you might even implement some kind of channel sets, where you could have mapping between 1 P-channel : N N-channel or the other way around , but this seems rather complex. I'm just adding this here as an option that came to me. Best regards, Marek Vasut -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
