You can use either powered or parasitic modes for One-Wire devices -- there isn't a distinct device for one mode or the other. The data sheet shows the DS18B20 can operate down to 3V.
I'm not greatly versed in embedded Linux, nor in the BBB, but I've used One-Wire devices (including DS18S20s) a fair bit. I avoid parasitic mode whenever I can. Running a power line makes One-Wire systems much easier to debug, and multi-wire cables aren't all that expensive. Cheers, Tim On Sunday, September 28, 2014 5:48:11 AM UTC-4, Michaël Vaes wrote: > > I was able to get the sensor showing up (switched + and -... Yeah to > quick), however I'm not able to get correct temperature readings with a new > sensor. > I need to mention that I have the Parasitic version DS18B20+, does that > work with 3.3VDC or do I need to connect it to 5VDC (which the BBB does not > support I believe, 5VDC inputs..) > > root@bbb:~# for i in `find /sys/devices/w1_bus_master1/ -type d -iname > "28-*"`; do echo -n $i' '; grep -oE "t=[0-9]+$" "$i/w1_slave"; done; > /sys/devices/w1_bus_master1/28-0000057ee219 t=85000 > /sys/devices/w1_bus_master1/28-0000057efe1e t=85000 > > Thanks, > *Michaël* > > > On Saturday, August 30, 2014 1:01:18 PM UTC+2, Michaël Vaes wrote: >> >> Hi - >> >> I'm stuck getting my DS18B20 temperature sensor working on my Beaglebone >> Black. I installed and loaded the DTC overlay but Im not getting the '28-*' >> files in my '/sys/devices/w1_bus_master1/' directory. >> >> *Wiring* >> >> https://dl.dropboxusercontent.com/u/97513059/ds18b20-temperature-sensor.pdf >> >> *Software* >> Debian 7.6 >> Kernel: 3.8.13-bone50 >> >> *My sensor:* http://www.mouser.com/ds/2/256/DS18B20-28978.pdf >> *My DTS file:* http://pastebin.com/ma7qd6HK >> >> *Latest version of dtc: *https://raw.githubusercontent.com/RobertCNelson/ >> tools/master/pkgs/dtc <http://goog_1232883269>.sh >> >> *Install* >> root@bbb:~# cat one-wire-temp-sensor_p8-11.sh >> #!/bin/bash >> # >> # BBB One Wire Temperature sensor (DS18B20) >> # >> >> sName='w1'; >> sInput=$sName'.dts'; >> sOutput=${sName:0:16}'-00A0.dtbo'; >> >> >> # Build >> /usr/local/bin/dtc -O dtb -o "$sOutput" -b 0 -@ "$sInput"; >> cp $sOutput /lib/firmware/; >> echo "$sName" > /sys/devices/bone_capemgr.9/slots; >> >> *GPIO's* >> Pin P8.11 gets high, when I test the voltage it's 3.3VDC. >> root@bbb:~# cat /sys/kernel/debug/gpio >> GPIOs 0-31, gpio: >> gpio-6 (mmc_cd ) in lo >> >> GPIOs 32-63, gpio: >> gpio-45 (w1 ) in hi >> gpio-52 (eMMC_RSTn ) out lo >> gpio-53 (beaglebone:green:usr) out lo >> gpio-54 (beaglebone:green:usr) out lo >> gpio-55 (beaglebone:green:usr) out hi >> gpio-56 (beaglebone:green:usr) out lo >> >> GPIOs 64-95, gpio: >> >> GPIOs 96-127, gpio: >> >> *Overlays* >> HDMI disabled, w1 overlay loaded >> root@bbb:~# 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-- Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI >> 6: ff:P-O-- Bone-Black-HDMIN,00A0,Texas Instrument,BB-BONELT-HDMIN >> 7: ff:P-O-L Override Board Name,00A0,Override Manuf,BB-UART1 >> 8: ff:P-O-L Override Board Name,00A0,Override Manuf,w1 >> >> *dmesg* >> root@bbb:~# dmesg | tail -n11 >> [ 167.078501] bone-capemgr bone_capemgr.9: part_number 'w1', version >> 'N/A' >> [ 167.078681] bone-capemgr bone_capemgr.9: slot #8: generic override >> [ 167.078726] bone-capemgr bone_capemgr.9: bone: Using override eeprom >> data at slot 8 >> [ 167.078775] bone-capemgr bone_capemgr.9: slot #8: 'Override Board >> Name,00A0,Override Manuf,w1' >> [ 167.079020] bone-capemgr bone_capemgr.9: slot #8: Requesting part >> number/version based 'w1-00A0.dtbo >> [ 167.079067] bone-capemgr bone_capemgr.9: slot #8: Requesting firmware >> 'w1-00A0.dtbo' for board-name 'Override Board Name', version '00A0' >> [ 167.082029] bone-capemgr bone_capemgr.9: slot #8: dtbo 'w1-00A0.dtbo' >> loaded; converting to live tree >> [ 167.082504] bone-capemgr bone_capemgr.9: slot #8: #2 overlays >> [ 167.089775] of_get_named_gpio_flags exited with status 45 >> [ 167.089820] of_get_named_gpio_flags: can't parse gpios property >> [ 167.097793] bone-capemgr bone_capemgr.9: slot #8: Applied #2 overlays. >> >> *Tryouts without success* >> >> - Reboots :o) >> - Using another temperature sensor >> - Updating the OS >> - Changing the DTS file to use another pin like 'P9.22' >> - >> >> http://hipstercircuits.com/dallas-one-wire-temperature-reading-on-beaglebone-black-with-dto/ >> - Changing 'gpios = <&gpio2 13 0>;' to 'gpios = <&gpio1 13 0>;' >> >> *What concerns me and where I cannot seem to get rid of in dmesg</b* >> ... > > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
