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resistor (kΩ) voltage (V) 0,468 0,03 1,0 0,064 1,5 0,095 10 0,56 15 0,78 39 1,485 ------------------ ∞ 3,3 (no resistor)
Yes.Burngate wrote:As far as I can see, and assuming GPIO-27 was set as an input for your tests, you've verified that the internal pull-down resistor is close to 50k.
Is that what you intended?
I am sorry, I do not know enough about electronics to understand what you wrote. I did not measure any clock, I was on GPIO 27 and this was set to input. Also, what is the connection of raspberry to printed circuit board (assuming that this stands for PCB)? I do not know how to deactivate the pull-down resistor, so I measured what I had at hand, etc.jdb wrote:That measurement is invalid
That can't be fully true. For example. many people use pifm to run GPIO up to 250 MHz in a very reliable way. Thus it is interesting to know what the resulting matching impedance at ~100 MHz should be.jdb wrote:Reliable operation with a clock at 100MHz is probably beyond the scope of the GPIOs brought out to the 40-pin header simply because that sort of header isn't designed to carry signals at that frequency.