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Hi guys!

Working at a new project. It`s a simple thermometer with 18B20 and 7 segment led (3 digits). Because of the limit of the pcb, I want to get rid of the oscillator, but notes that it is not a lucky choice...
Is there any reason that 18B20 not work without external clock? The pic is 16F648A and the configuration word is 0X3F18 (all off). The pic it works (it starting), I did some tests with seven segments and everything seems to be ok with the pic, but no response from 18b20 sensor. If I put quartz and change the configuration for external clock, everything is OK, I can read the sensor ...

Does your project work if you use a 4mHz quartz crystal? I do not know of any reason why it would not work using the internal 4mHz oscillator.

Nope... The minimum frequency that can operate the project is 8 MHz external clock... At 4 MHz, it stalled... I have no idea why below 8 MHz, DS it stops?!

Does anyone have an example of a thermometer with 7 segment display? If so, please post it here. Thank you very much!