Fix blink example by correctly toggling output #79
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The blink example was incorrect (as pointed out in issue micropython#78). The example was toggling the GPIOs "output enable" state, instead of keeping "output enable" on and then toggling the output value of the pin. It "accidentally" worked, because we initally set the output value to 1 (high) and thus, whenever "output enable" was set, the LED lit up, and when "output enable" was turned off, the pin was left floating without any output voltage and the LED therefore turned off. The new approach correctly enables "output enable" at the start, and then only toggles the output value of the pin on and off. This change was also tested with a logic analyser, showing that before this change, the logic analyser could not correcly detect a LOW state after a HIGH state, because the pin was floating without a pull-down resistor in place, whenever it was not in "output enable" mode. After this change, the logic analyser correctly detected all LOW and HIGH states, because the pin remained in "output enable" mode (and the ESP32 has a pull-down configured by default) and only the output value was toggled.
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The blink example was toggling the GPIOs "output enable" state, instead of keeping "output enable" on and then toggling the output value of the pin. (reported in #78)
This PR fixes the problem by enabling "output enable" at the start, and then only toggling the output value of the pin "on" and "off". (Documentation for the used register constants can be found here and here)
The change was tested with a logic analyser to confirm the expected change.
More details in the commit message.
Resolves issue #78.