you have a pull up for each ds18? but they are all on the same bus? 4 resistors of 5k each like that is the same as on of 1250 ohm.
Yes you are correct. I quickly snapped those pictures mid development (more like tinkering) when I first got them all recognized so I wouldn’t forget after I kept taking it further. Each of those circuits actually goes to a string of a few sensors each ( to different greenhouses on the same farm ) and some python then controls gpio pins to trigger relays to turn on heating devices (in morning cold) and cooling devices (afternoon sun) to maintain optimal temperatures (in each greenhouse). Also to note, the 3.3v vcc used in deployed version comes from a separate power supply (DIN rail mounted) that provides regulated voltage to both beagle and sensor network so the sensors are not powered through the beagle (originally developed for powering arduino board and same string of sensors, changed the voltage regulator for the sensor power from 5v to 3.3v).
This also explains that I don’t know that much about all this engineering stuff, my focus is on growing healthy organic produce. My free time goes to making the chores of my children easier so they can focus on whats important, protecting and perfecting(nutrient and environment profiles) landrace genetics (each which requires specific environmental conditions to prevent adaptive mutations). Please if you know more than me about these sensor networks, take pictures and share the knowledge of the best way to string up 50 of em, your knowledge of electronics might help improve the overall heath of humanity. Huge amounts of gratitude to all that have contributed to the development of the beaglebone and linux, it is rare to find a giant with a saddle on its back ready for riders.
actually, your other comment did it for me: make sure you connect it correctly. somehow I was confused by the ds18b20 data sheet. the drawing with the pin assignments is from the bottom. I now have 3 on the same bus without pull resistors. it works perfectly.
still I am wondering how I can send other commands and if I can connect other 1-wire devices…
tnx
let us know if you figure out how to ‘set resolution (9bitvs12bit)’ and other such tasks. Also, some w1 devices have their own kernel-module while some don’t (list from opkg to see whats already working), let us know what other sensors you get working.
Just curious, why would you want less than 12 bits? You can always ignore the last 3 bits if you don’t mind the accuracy?
I think you can add another w1-gpio device, but I haven't actually tried doing that.
Hi Agit,
I am facing same problem, did u get any solution for this?
cheers,
irfan
ptech, you seem to be on to something that I am trying to accomplish. Your pics are private so I could not see them. Can you please post your breadboard layout with the ds18b20 and BBB, and the schematic. I am as far as connecting the 47k ohm resistor to the data wire on the ds18b20. I have a gpio set as input and one as output to a led. You see I am newbe.