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> You get a higher quality reply if you email me directly rather than via the list
> ;-)
Yes, but then others wouldn't know about the meetings in Plymouth :D
(I love watching email conversations go widely away from their subject line...)
Thanks for the info Gordon - I'll have a dive in to what you've written below.
-----Original Message-----
From: list [mailto:list-bounces@xxxxxxxxxxxx] On Behalf Of Gordon Henderson via list
Sent: 16 February 2017 19:37
To: list@xxxxxxxxxxxxx
Subject: Re: [LUG] WiringPi - 1 Wire?
On Thu, 16 Feb 2017, Tremayne, Steve via list wrote:
> Gordon,
You get a higher quality reply if you email me directly rather than via the list ;-)
> I was "fiddling" with a Ras Pi Zero and a 1-wire temp sensor yesterday...
>
> Does your Wiring Pi deal with 1-wire? I got no search results from
> the site, so I'm presuming not?
1-wire is handled very well by the Linux kernel and its owfs (one-wire filing
system), so there's no need for me to write anything for something that's already
there.
However, for the common ds18b20 1-wire temperature sensors, I've created a pin
wrapper for them to better integrate them into the wiringPi world.
You'll need to install the latest wiringPi from source though.
http://wiringpi.com/download-and-install/
then run:
sudo raspi-config
go through the menus and enable 1-wire. Plug in the sensor - it's fixed to bcm_gpio
pin 4 (physical pin 7) then
ls /sys/bus/w1/devices
If you see a 28-????? file, then the ds18b20 is present. You can cat this
file/w1_slave - e.g.:
$ cat /sys/bus/w1/devices/28-0000053af458/w1_slave
f6 00 4b 46 7f ff 0a 10 d6 : crc=d6 YES
f6 00 4b 46 7f ff 0a 10 d6 t=15375
your filename will be different from mine - each device has a unique 64-bit ID and
mine is: 0000053af458.
In the output above, YES means a good read and t=15375 is the temperature times
1000. Remember these are +/- 1ÂC devices, so round and truncate appropriately.
With the latest wiringPi:
$ gpio -x ds18b20:100:0000053af458 aread 100
154
means 15.4ÂC.
In a C program:
#include <ds18b20.h>
int temp10 ;
if (ds18b20Setup (pinBase, "0000053af458") < 0)
.. something went wrong exit (1) ;
temp10 = analogRead (pinBase) ;
returns the temperature times 10 as an integer.
Reading takes about 3/4 a second.
> It's been a while since I've really done much "fiddling" with
> electronics, so I'm finding more rust on my brain than I thought - so,
> if 1-wire is handled by I2C / SPI, then apologies... I'll just go and
> RTFM...
It's handled directly. Use BCM_GPIO pin 4 and off you go.
Gordon
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