Simulating a DS18B20

[keithdoxey]

Has anyone simulated a DS18B20 temperature sensor with a potentiometer before? I need to do this for a project that has 5 of them running, each with its own I/O and not running on a 1-wire bus though. All of them are running in 12-bit mode too. I'm going to use another PIC to be the fake sensors but I'm not sure how to even start to get this work properly. I know I have to load an array of 9 bytes with the first two being the temperature and the last one being the CRC.

I would suggest that trying to fake the data that would be returned by the sensors would be a nightmare. You would have to get Pic#2 to behave EXACTLY the same as a DS18B20.

I would use 5 of the real sensors as someone else suggested but strap each one to one of the aluminium clad power resistors. you could then vary the current through the resistor to adjust the temperature sensed by each individual sensor.

Many times in the past I have tried to fake data but it isnt a true test for the real world. Using the method above is still faking, but faking the environment not the hardware/software so should be much closer to a real world scenareo

[CocaColaKid]

Keith,

Thanks for the advise but i need to be able to run them down to -25C and up to 30C. Power resistors wont work well for this type of testing though. I heat pump might work but requires a lot of power though.

[keithdoxey]

Keith,

Thanks for the advise but i need to be able to run them down to -25C and up to 30C. Power resistors wont work well for this type of testing though. I heat pump might work but requires a lot of power though.

Was worth a try

How about using the power resistors and sticking the whole assembly in the deep freeze. LOL

[Archangel]

wouldn't it be possible to use your PC to output the binary or hex code expected from a 3 wire device? The data sheet has a table of temp to code conversion, why can not you simply send it frrom the serial port?