Re: [beagleboard] 1-wire not working

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Jim F

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Nov 18, 2019, 11:58:28 AM11/18/19
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1w didn't work in that version of Linux. It works in 4.14 if you enable the dtb file in uenv.txt. So I think you'll have to update. 

It looks like it should support multiple devices, but we're only using one, so I haven't tried.

Good luck. 

-j

On Mon, Nov 18, 2019, 10:28 AM Fohnbit <ged...@gmail.com> wrote:
Hello,

I tried to enable 1-wire, but did not found some paths .. maybe my installation is different?

I´m not sure what you need, so I write what I did so far:

/boot/uEnv.txt:
#Docs: http://elinux.org/Beagleboard:U-boot_partitioning_layout_2.0

uname_r
=4.9.82-ti-r102
#uuid=
#dtb=

###U-Boot Overlays###
###Documentation: http://elinux.org/Beagleboard:BeagleBoneBlack_Debian#U-Boot_Overlays
###Master Enable
enable_uboot_overlays
=1
###
###Overide capes with eeprom
uboot_overlay_addr0
=/lib/firmware/BB-UART1-00A0.dtbo
uboot_overlay_addr1
=/lib/firmware/BB-UART4-00A0.dtbo
uboot_overlay_addr2
=/lib/firmware/BB-W1-P9.12-00A0.dtbo

###Cape Universal Enable
enable_uboot_cape_universal
=1
###

###U-Boot Overlays###
cape_disable
=bone_capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN
cape_enable
=bone_capemgr.enable_partno=BB-UART1,BB-UART4

cmdline
=coherent_pool=1M net.ifnames=0 quiet

I connect P9.12 to the 1-wires ... also GND and VCC (5V)

the first issue:
I don´t have this folder.
/sys/devices/bone_capemgr.9/slots

Did this mean I have a different version?
But I have this folder:
/sys/devices/w1_bus_master1/

So the 1-wire is loaded and working?
I added:

/etc/modules
w1-gpio
w1-therm


But no sensor is found:

cat /sys/devices/w1_bus_master1/w1_master_slaves
not found.

I appreciate for help!

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Mark A. Yoder

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Nov 19, 2019, 11:22:12 AM11/19/19
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The one-wire device appears in a different place now.

Here's an example I worked up that's from https://elinux.org/EBC_Exercise_31_Dallas_1-Wire

Reading the DS18B20[edit]

bone$ cd /sys/class/hwmon/
hwmon0  hwmon1

Oh, we have two devices here. Let's see which is which

bone$ cat */name
w1_slave_temp
tmp101

So one is our one-wire temp sensor and the other is a tmp101 sensor. Let's read ours.

bone$ cd hwmon0
bone$ ls
device  name  power  subsystem  temp1_input  uevent
bone$ cat temp1_input
20812

The 20812 is the temperature in C times 1000, that is, divide this number by 1000 to get the temp in C.

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