As I stated when I put it there, it came from the Arduino docs.
Vince.
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On 10/01/2017 07:38 PM, Allard PE1NWL wrote:
On Sun, Oct 1, 2017 at 04:01 pm, Vince Vielhaber wrote:
On the digital pins:
There are 20K pullup resistors built into the Atmega chip that can
be accessed from software. These built-in pullup resistors are
accessed by setting the pinMode() as INPUT_PULLUP. This effectively
inverts the behavior of the INPUT mode, where HIGH means the sensor
is off, and LOW means the sensor is on.
This is absolutely INCORRECT.
pinMode(xx, INPUT) and pinMode(xx, INPUT_PULLUP) only enable/disable the
internal pull up resistors.
They DON'T invert the behaviour of the input!
73 Allard PE1NWL
--
Michigan VHF Corp.
