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From: John Aldridge <jpsa@cantab.net>
Newsgroups: comp.sys.raspberry-pi
Subject: Re: 1-wire behaviour on Bookworm
Date: Sun, 22 Sep 2024 11:53:07 +0100
Organization: A noiseless patient Spider
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References: <vcgrag$gsv0$2@dont-email.me> <MPG.41575c0e6e1470fe9897c0@news.eternal-september.org> <vckmfh$17vkc$2@dont-email.me>
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In article <vckmfh$17vkc$2@dont-email.me>, news@druck.org.uk says...
> 
> On 20/09/2024 11:17, John Aldridge wrote:
> [Reading ds18b20 sensors in parallel]
> > No, but AIUI the "right" way to do this is to send the text "trigger" to
> > /sys/bus/w1/devices/w1_bus_master1/therm_bulk_read before reading the
> > values as normal. The trigger causes them all to start a conversion at
> > once, following which the reads all complete immediately once a single
> > conversion time has elapsed.
> > 
> > As a quick hack, try executing the following before reading your
> > sensors...
> > 
> > sudo su <<EOF
> > echo trigger > /sys/bus/w1/devices/w1_bus_master1/therm_bulk_read
> > EOF
> 
> Thanks, that seems to works for the first bus, but I get a permission 
> denied when using w1_bus_master2.

Sorry, I've no idea why that might be :(

Though I do recall the permission checking being a bit odd -- hence the 
"sudo su" rather than a plain "sudo".

-- 
John