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Forum Index : Microcontroller and PC projects : Multiple onewire devices

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Chopperp

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Joined: 03/01/2018
Location: Australia
Posts: 1097
Posted: 10:47pm 01 Sep 2020
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Yes, the mod is specific to my needs & they did work with shorter times.

I was wondering why all readings were taking the same length of time.

Using onewire with multiple devices means you have to get the codes & find out which one is which is obviously done individually but you need track of them. Also, if a sensor is replaced, it's code is needed & software updated accordingly.

One thing I found out yesterday when playing & reading the data sheets & the manual etc was about the strong pull-up that is used in the parasitic mode.

I was always under the impression that you really needed an external deice to do that. (not that I did).

It dawned on me that the data input gets changed to an output & set high for the period required. It even says this for flag 8 in Appendix C.

EDIT

Of course, an external device (MOSFET) can be used if not provided in for firmware. 

More playing.

Thanks.

Brian
Edited 2020-09-02 12:13 by Chopperp
ChopperP
 
Chopperp

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Joined: 03/01/2018
Location: Australia
Posts: 1097
Posted: 12:11pm 08 Sep 2020
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FYI

Purchased 5 new DS18B20+ sensors from RS after making sure they were not the "P" type.
Results below. Definitely different.

Thanks again Jim for the help & code.


16
Power =  1  -0.5

Power =  1  2804C3360C000054   87  24
Power =  1  2804C3360C000054   163  23.75
Power =  1  2804C3360C000054   312  23.5
Power =  1  2804C3360C000054   612  23.4375

Power =  1  287A0E370C00009E   88  24
Power =  1  287A0E370C00009E   163  24
Power =  1  287A0E370C00009E   312  23.875
Power =  1  287A0E370C00009E   612  23.8125

Power =  1  28FA95370C0000B3   89  24
Power =  1  28FA95370C0000B3   166  24
Power =  1  28FA95370C0000B3   320  23.875
Power =  1  28FA95370C0000B3   627  23.8125

Power =  1  282E46360C000034   89  24
Power =  1  282E46360C000034   166  24
Power =  1  282E46360C000034   318  23.875
Power =  1  282E46360C000034   623  23.875

Power =  1  28AB29360C00004B   88  24
Power =  1  28AB29360C00004B   165  23.75
Power =  1  28AB29360C00004B   317  23.75
Power =  1  28AB29360C00004B   620  23.75



Power =  1   24  bit = 9 q =  0
Power =  1   23.75  bit = 10 q =  1
Power =  1   23.5  bit = 11 q =  2
Power =  1   23.4375  bit = 12 q =  3
Power =  1   24  bit = 9 q =  4
Power =  1   24  bit = 9 q =  5
Power =  1   24  bit = 9 q =  6
Power =  1   24  bit = 9 q =  7
Power =  1   24  bit = 9 q =  8
Power =  1   24  bit = 9 q =  9
Power =  1   23.75  bit = 10 q =  10
Power =  1   23.5  bit = 11 q =  11
Power =  1   23.5  bit = 12 q =  12
Power =  1   23.5  bit = 12 q =  13
Power =  1   23.5  bit = 12 q =  14
>

Brian
ChopperP
 
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