On 30/05/2018 22:23, Tomasz Duszynski wrote:
On Wed, May 30, 2018 at 03:20:37PM +0800, Matt Ranostay wrote:
On Wed, May 30, 2018 at 1:05 PM, Matt Ranostay
<matt.ranostay@xxxxxxxxxxxx> wrote:
On Wed, May 30, 2018 at 9:17 AM, Phil Reid <preid@xxxxxxxxxxxxxxxxx> wrote:
On 30/05/2018 08:44, Matt Ranostay wrote:
On Mon, May 28, 2018 at 11:38 PM, Tomasz Duszynski <tduszyns@xxxxxxxxx>
wrote:
According to IIO ABI relative humidity reading should be
returned in milli percent.
This patch addresses that by applying proper scaling and
returning integer instead of fractional format type specifier.
*sigh* seems this is my mistake, but good catch. Slight nitpick
below.. otherwise looks good
Signed-off-by: Tomasz Duszynski <tduszyns@xxxxxxxxx>
---
drivers/iio/pressure/bmp280-core.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/iio/pressure/bmp280-core.c
b/drivers/iio/pressure/bmp280-core.c
index 5ec3e41b65f2..fe87d27779d9 100644
--- a/drivers/iio/pressure/bmp280-core.c
+++ b/drivers/iio/pressure/bmp280-core.c
@@ -415,10 +415,9 @@ static int bmp280_read_humid(struct bmp280_data
*data, int *val, int *val2)
}
comp_humidity = bmp280_compensate_humidity(data, adc_humidity);
- *val = comp_humidity;
- *val2 = 1024;
+ *val = comp_humidity * 1000 / 1024;
Minor nitpick that it would look cleaner as: (comp_humidity / 1024) *
1000
be careful of integer division.
Ah yes good point. You will have to check if comp_humidity isn't zero
or it is possible to have a divide-by-zero.
D'oh actually divide by zero would be an issue. But you'll want to be
sure of possible overflows (doubt that would be an issue here).
What kind of division-by-zero are you meaning? When would that happen
in this case?
I meant something like this:
10 / 1024 = 0
0 * 1000 = 0
10 * 1000 = 10000
10000 / 1024 = 9
patch looks like the right way to me
provided comp_humidity * 1000 is not going to overflow.
However it may be better to just add the scaling factor of 1000 with
IIO_CHAN_INFO_SCALE and make the processed value now a raw one.
Is measurement precision your concern here? I would not bother with that
since the sensor is not a top-notch anyway. Even datasheet itself specifies
error margin of +/-3% for relative humidity.
- Matt
- return IIO_VAL_FRACTIONAL;
+ return IIO_VAL_INT;
}
static int bmp280_read_raw(struct iio_dev *indio_dev,
--
2.17.0
--
Regards
Phil Reid
--
Regards
Phil Reid
ElectroMagnetic Imaging Technology Pty Ltd
Development of Geophysical Instrumentation & Software
www.electromag.com.au
3 The Avenue, Midland WA 6056, AUSTRALIA
Ph: +61 8 9250 8100
Fax: +61 8 9250 7100
Email: preid@xxxxxxxxxxxxxxxxx
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