troubleshooting DS18B20 temperature sensors on BBB debian V 7.8

Hi All GPIO Gurus,

Thanks very much for taking the time to read this.

I’ve been following the documented processes (e.g.
to get a 1 wire interface up and running to read several DS18B20 temperature sensors.

I’ve got a .dts to load, and the overlay is showing in slots, but the sensors (I’ve used several 5 different ones) are never detected.

I’m using the device tree overlay from the above web site, and the same hardware layout.

using dmesg | grep bone_cape suggests the overlay loaded successfully:


[ 8.697062] bone-capemgr bone_capemgr.9: part_number ‘w1’, version ‘N/A’
[ 8.697138] bone-capemgr bone_capemgr.9: slot #7: generic override
[ 8.697155] bone-capemgr bone_capemgr.9: bone: Using override eeprom data at slot 7
[ 8.697171] bone-capemgr bone_capemgr.9: slot #7: ‘Override Board Name,00A0,Override Manuf,w1’
[ 8.697259] bone-capemgr bone_capemgr.9: slot #7: Requesting part number/version based 'w1-00A0.dtbo
[ 8.697274] bone-capemgr bone_capemgr.9: slot #7: Requesting firmware ‘w1-00A0.dtbo’ for board-name ‘Override Board Name’, version ‘00A0’
[ 8.727950] bone-capemgr bone_capemgr.9: slot #7: dtbo ‘w1-00A0.dtbo’ loaded; converting to live tree
[ 8.728198] bone-capemgr bone_capemgr.9: slot #7: #2 overlays
[ 8.757662] bone-capemgr bone_capemgr.9: slot #7: Applied #2 overlays.


and the appropriate overlay appears in the slots:

root@beaglebone:~# cat /sys/devices/bone_capemgr.9/slots 0: 54:PF--- 1: 55:PF--- 2: 56:PF--- 3: 57:PF--- 4: ff:P-O-L Bone-LT-eMMC-2G,00A0,Texas Instrument,BB-BONE-EMMC-2G 5: ff:P-O-L Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI 7: ff:P-O-L Override Board Name,00A0,Override Manuf,w1

However, when I look in the appropriate directory for the device file, no devices appear:

root@beaglebone:~# ls /sys/bus/w1/devices/w1_bus_master1
driver power subsystem uevent w1_master_add w1_master_attempts w1_master_max_slave_count w1_master_name w1_master_pointer w1_master_pullup w1_master_remove w1_master_search w1_master_slave_count w1_master_slaves w1_master_timeout

I’ve used two different BBB’s, and 5 different sensors, singly or in combination. None of them. Volatages across the grnd and power pins are showing at the expected approx 3.3 volts, as is voltage across the DQ-grnd.

Kernel version is:


I’ve run out of troubleshooting tests – and would appreciate some suggestions as to what else to look for.

Thanks for your help!

Kind regards