Re: iio: dht11 Updates

From: Richard Weinberger <richard@nod.at>
To: Harald Geyer <harald@ccbib.org>
Cc: jic23@kernel.org, knaack.h@gmx.de, lars@metafoo.de,
	pmeerw@pmeerw.net, sanjeev_sharma@mentor.com,
	linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: iio: dht11 Updates
Date: Wed, 03 Dec 2014 23:05:25 +0100	[thread overview]
Message-ID: <547F8925.3050308@nod.at> (raw)
In-Reply-To: <E1XwAbX-0001Ht-Jg@stardust.g4.wien.funkfeuer.at>

Am 03.12.2014 um 15:08 schrieb Harald Geyer:
>> I was asking because I see the "dht11: WARNING: decoding ambiguous"
>> very often. (with and without my patches)
> 
> Yes, your patches shouldn't have any effect on this.
> "very often" in the sense of "not always"? This would be very surprising,
> because this would involve variable length clock ticks, i think.
> 
> I guess we should include timeres into the warning message.
> 
> Also I guess now is the time to think about a smarter decoder.

Another question. Your driver defines:
#define DHT11_DATA_BIT_LOW      27000
#define DHT11_DATA_BIT_HIGH     70000

If I read the manual [0] correctly these constants are T_h0/1.
Why did you use 27000 for T_h0?
Setting it to 26000 (the typical value as stated by the manual),
I get the "decoding ambiguous" warning *always*. Setting it higher
makes the message go away.

Thanks,
//richard

[0] http://meteobox.tk/files/AM2302.pdf