Hi Jacopo, On Mon, Oct 17, 2022 at 06:31:59PM +0200, Jacopo Mondi wrote: > Hi Sakari, > > On Mon, Oct 17, 2022 at 06:57:48PM +0300, Sakari Ailus wrote: > > Hi Jacopo, > > > > On Mon, Oct 17, 2022 at 05:10:03PM +0200, Jacopo Mondi wrote: > > > > which is also named analog_gain_code_global, but is documented > > > > differently. > > > > > > > > Could you btw read registers 0x0000 to 0x00ff and provide the data ? > > > > > > There is nothing interesting there if not default values. I was hoping > > > that analogue_gain_m0 analogue_gain_c0 and analogue_gain_m1 > > > analogue_gain_c1 would provide a way to inject gains using the > > > standard CCS gain model, but those registers are said to be read-only > > > > The m[01] and c[01] factors in the CCS analogue gain formula are constants > > that determine how the sensor's analogue gain setting translates to actual > > analogue gain. They are not intended to be modifiable at runtime. > > > > You're right sorry, indeed they're constant. > > For this sensor: > analogue_gain_type: 0 > analogue_gain_m0: 1 > analogue_gain_c0: 0 > analogue_gain_m1: 0 > analogue_gain_c1: 4 > > I should be capable of programming the global analog gain using the linear > CCS gain model if the sensor is actually CCS compliant. > > gain = m0 * x + c0 / m1 * x + c1 > = R0x0204 / 4 > > However, the application developer guide shows the gain to be set > through manufacturer specific registers (0x3028 or 0x305e) and I cannot > find much correlations between the manufacturer specific gain model > (a piecewise exponential function) and the model described by CCS, which > seems way simpler. I wonder if the values in these registers are just leftovers from an earlier sensor. If the device implements a device specific gain model, it is unlikely to support the CCS model(s). There is also an alternative to the traditional CCS gain model, in section 9.3.2 of the spec version 1.1. The formula in that case is: gain = analogue_linear_gain_global * 2 ^ analogue_exponential_gain_global -- Kind regards, Sakari Ailus
