2022-03-27 00:47:21

by Jagath Jog J

Subject: [PATCH v2 1/5] iio: accel: bma400: Fix the scale min and max macro values

Changing the scale macro values to match the bma400 sensitivity
for 1 LSB of all the available ranges.

Signed-off-by: Jagath Jog J <[email protected]>
---
drivers/iio/accel/bma400.h | 22 ++++++++++++++++++++--
1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/accel/bma400.h b/drivers/iio/accel/bma400.h
index c4c8d74155c2..190366debdb3 100644
--- a/drivers/iio/accel/bma400.h
+++ b/drivers/iio/accel/bma400.h
@@ -83,8 +83,26 @@
#define BMA400_ACC_ODR_MIN_WHOLE_HZ 25
#define BMA400_ACC_ODR_MIN_HZ 12

-#define BMA400_SCALE_MIN 38357
-#define BMA400_SCALE_MAX 306864
+/* BMA400_SCALE_MIN macro value represents m/s^2 for 1 LSB before
+ * converting to micro values for +-2g range.
+ *
+ * For +-2g - 1 LSB = 0.976562 milli g = 0.009576 m/s^2
+ * For +-4g - 1 LSB = 1.953125 milli g = 0.019153 m/s^2
+ * For +-16g - 1 LSB = 7.8125 milli g = 0.076614 m/s^2
+ *
+ * The raw value which is used to select the different ranges is determined
+ * by the first bit set position from the scale value, so BMA400_SCALE_MIN
+ * should be odd.
+ *
+ * Scale values for +-2g, +-4g, +-8g and +-16g is populated into bma400_scales
+ * array by left shifting BMA400_SCALE_MIN.
+ * eg:
+ * To select +-2g = 9577 << 0 = raw value to write is 0.
+ * To select +-8g = 9577 << 2 = raw value to write is 2.
+ * To select +-16g = 9677 << 3 = raw value to write is 3.
+ */
+#define BMA400_SCALE_MIN 9577
+#define BMA400_SCALE_MAX 76617

#define BMA400_NUM_REGULATORS 2
#define BMA400_VDD_REGULATOR 0
--
2.17.1

2022-03-28 11:20:17

by Jonathan Cameron

Subject: Re: [PATCH v2 1/5] iio: accel: bma400: Fix the scale min and max macro values

On Sun, 27 Mar 2022 01:11:42 +0530
Jagath Jog J <[email protected]> wrote:

> Changing the scale macro values to match the bma400 sensitivity
> for 1 LSB of all the available ranges.
>
> Signed-off-by: Jagath Jog J <[email protected]>
Hi Jagath,

> ---
> drivers/iio/accel/bma400.h | 22 ++++++++++++++++++++--
> 1 file changed, 20 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iio/accel/bma400.h b/drivers/iio/accel/bma400.h
> index c4c8d74155c2..190366debdb3 100644
> --- a/drivers/iio/accel/bma400.h
> +++ b/drivers/iio/accel/bma400.h
> @@ -83,8 +83,26 @@
> #define BMA400_ACC_ODR_MIN_WHOLE_HZ 25
> #define BMA400_ACC_ODR_MIN_HZ 12
>
> -#define BMA400_SCALE_MIN 38357
> -#define BMA400_SCALE_MAX 306864
> +/* BMA400_SCALE_MIN macro value represents m/s^2 for 1 LSB before
Multiline comment syntax in IIO is
/*
* BMA400....

> + * converting to micro values for +-2g range.
> + *
> + * For +-2g - 1 LSB = 0.976562 milli g = 0.009576 m/s^2
> + * For +-4g - 1 LSB = 1.953125 milli g = 0.019153 m/s^2
> + * For +-16g - 1 LSB = 7.8125 milli g = 0.076614 m/s^2
> + *
> + * The raw value which is used to select the different ranges is determined
> + * by the first bit set position from the scale value, so BMA400_SCALE_MIN
> + * should be odd.
> + *
> + * Scale values for +-2g, +-4g, +-8g and +-16g is populated into bma400_scales
> + * array by left shifting BMA400_SCALE_MIN.
> + * eg:
> + * To select +-2g = 9577 << 0 = raw value to write is 0.
> + * To select +-8g = 9577 << 2 = raw value to write is 2.
> + * To select +-16g = 9677 << 3 = raw value to write is 3.

9667?

> + */
> +#define BMA400_SCALE_MIN 9577
> +#define BMA400_SCALE_MAX 76617
>
> #define BMA400_NUM_REGULATORS 2
> #define BMA400_VDD_REGULATOR 0