* [PATCH] iio: dht11: Improve detection of sensor type
@ 2018-02-11 11:09 Harald Geyer
2018-02-17 12:06 ` Jonathan Cameron
0 siblings, 1 reply; 2+ messages in thread
From: Harald Geyer @ 2018-02-11 11:09 UTC (permalink / raw)
To: Jonathan Cameron; +Cc: linux-iio, Edward Attfield, Harald Geyer
The old code was based on a DHT11 datasheet which specifies a measurement
range of 20%-90% RH. Turns out the sensor actually reports values outside
this range, so we should support it as far as possible.
Reported-by: Edward Attfield <edward@attfield.ca>
Signed-off-by: Harald Geyer <harald@ccbib.org>
---
drivers/iio/humidity/dht11.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/iio/humidity/dht11.c b/drivers/iio/humidity/dht11.c
index df6bab4..1a9f8f4 100644
--- a/drivers/iio/humidity/dht11.c
+++ b/drivers/iio/humidity/dht11.c
@@ -159,7 +159,7 @@ static int dht11_decode(struct dht11 *dht11, int offset)
}
dht11->timestamp = ktime_get_boot_ns();
- if (hum_int < 20) { /* DHT22 */
+ if (hum_int < 4) { /* DHT22: 100000 = (3*256+232)*100 */
dht11->temperature = (((temp_int & 0x7f) << 8) + temp_dec) *
((temp_int & 0x80) ? -100 : 100);
dht11->humidity = ((hum_int << 8) + hum_dec) * 100;
--
2.1.4
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] iio: dht11: Improve detection of sensor type
2018-02-11 11:09 [PATCH] iio: dht11: Improve detection of sensor type Harald Geyer
@ 2018-02-17 12:06 ` Jonathan Cameron
0 siblings, 0 replies; 2+ messages in thread
From: Jonathan Cameron @ 2018-02-17 12:06 UTC (permalink / raw)
To: Harald Geyer; +Cc: linux-iio, Edward Attfield
On Sun, 11 Feb 2018 11:09:40 +0000
Harald Geyer <harald@ccbib.org> wrote:
> The old code was based on a DHT11 datasheet which specifies a measurement
> range of 20%-90% RH. Turns out the sensor actually reports values outside
> this range, so we should support it as far as possible.
>
> Reported-by: Edward Attfield <edward@attfield.ca>
> Signed-off-by: Harald Geyer <harald@ccbib.org>
Applied to the togreg branch of iio.git and pushed out as
testing for the autobuilders to play with it.
Thanks,
Jonathan
> ---
> drivers/iio/humidity/dht11.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/iio/humidity/dht11.c b/drivers/iio/humidity/dht11.c
> index df6bab4..1a9f8f4 100644
> --- a/drivers/iio/humidity/dht11.c
> +++ b/drivers/iio/humidity/dht11.c
> @@ -159,7 +159,7 @@ static int dht11_decode(struct dht11 *dht11, int offset)
> }
>
> dht11->timestamp = ktime_get_boot_ns();
> - if (hum_int < 20) { /* DHT22 */
> + if (hum_int < 4) { /* DHT22: 100000 = (3*256+232)*100 */
> dht11->temperature = (((temp_int & 0x7f) << 8) + temp_dec) *
> ((temp_int & 0x80) ? -100 : 100);
> dht11->humidity = ((hum_int << 8) + hum_dec) * 100;
^ permalink raw reply [flat|nested] 2+ messages in thread
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2018-02-11 11:09 [PATCH] iio: dht11: Improve detection of sensor type Harald Geyer
2018-02-17 12:06 ` Jonathan Cameron
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