On Thu, 2024-05-02 at 13:15 -0500, Adam Rizkalla wrote: > On Thu, May 02, 2024 at 07:16:16PM +0200, Vasileios Amoiridis wrote: > > Hi Angel! > > > > Indeed the datasheet says that the pressure is a signed value. But this > > comes > > in contrast with 2 things: > > > > 1) The BMP58x sensor does not have a compensation function so the value from > > the > > sensor is a pressure value just in different unit from the one reported by > > IIO. > > And the sensor is able to report in between 30-125kPa according to the > > datasheet which are both positive values so it makes more sense to be an > > unsigned value. > > > > 2) According to the BMP5 sensor API [1] provided by Bosch, the pressure is > > declared as an unsigned value. > > > > So, what should we trust? > > > > [1]: > > https://github.com/boschsensortec/BMP5_SensorAPI/blob/master/bmp5_defs.h#L895 > > The pressure sensor reading cannot be negative, as the pressure range of the > sensor > is 300 - 1250 hPa,so this change does not need to be applied for > bmp580_read_press(). > Also, the overflow issue does not happen with the pressure reading since the > value > read back from the device is scaled up only by 2^6 for pressure vs 2^16 for > temperature, > so multiplying by 1000 even for the maximum value would still fit in a 32-bit > signed > integer. Temperature ranges above ~32.767C, however, will overflow a 32-bit > signed > integer when multiplied by 2^16 * 1000 which is why this change is necessary > only for > temperature readings. > > Hope this helps clarify. > > Best, > Adam Crystal clear. Thanks to both of you for the clarifications :) Acked-by: Angel Iglesias <ang.iglesiasg@xxxxxxxxx> Kind regards, Angel
