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neuoy / OneWireArduinoSlave

An arduino library to communicate using the Dallas one-wire protocol, where the Arduino takes the role of a slave. Entirely implemented using interrupts, you can perform other tasks while communication is handled in background.
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Use sample code with ds2482-800 #12

Open ferec opened 7 years ago

ferec commented 7 years ago

Hello guys,

I am trying to figure out how to use this library with ds2482. I have a working code for communicating with a real DS18b20 thermometer, it does not work with this lib. In the detection phase I've got invalid commands on Arduino side like 0x65 or 0xd9. Maybe some timing problem?

I am using Arduino Uno with original board. DS2482 communicates with a short cable directly, Raspberry Pi B+ on the I2C side. This communication works with different 1-wire ICs like DS2450, DS2408.

Thank you for your suggestions.

Ferenc

Update: Problem is caused by pulling down the data pin for 750ms, that is detected as a reset signal. Removing this condition, the communication works. Disabling reset detection while in conversion state can help.

neuoy commented 7 years ago

Hi Ferenc,

Sorry for the late reply, and thanks for the update. I'll check the 1-wire specs and the other masters reset timing, and see if I can find a condition that satisfies all the masters tested with the library at this time (i.e. another arduino as master, which depends on the library used on the other arduino, or a DS9490R, or a DS2482 in your case). I suppose it's possible since standard 1-wire slaves seem to work fine in all these situations.

ferec commented 7 years ago

Hello,

It looks problem is not in library itself, just in the sample code for ds18b20.

neuoy commented 7 years ago

Hmm, do you mean that, while performing the conversion, the fake DS18B20 pulls the bus low, which resets itself? That would mean it doesn't work with other masters either? I'll take a closer look at what it's supposed to do when I have some time.

But that would not explain why you got invalid commands, like 0x65 or 0xd9?

ferec commented 7 years ago

At first time I added some Serial code into sample causing random bits/bytes received. After reinstalling the library and trying the sample code it still did not work. Then I used oscilloscope and logical analyzer to figure out whats going on. Then I realized that the fake pull-down triggers the reset event on bus.