Syntax: TOGGLE Pin
Invert the state of an output pin.
* Note: expressions are not allowed as arguments on the BS1. The range of the Pin argument on the BS1 is 0–7.
|BS1||All BS2 models|
TOGGLE sets a pin to output mode and inverts the output state of the pin, changing 0 to 1 and 1 to 0.
In some situations TOGGLE may appear to have no effect on a pin's state. For example, suppose pin 2 is in input mode and pulled to +5V by a 10 kΩ resistor. Then the following code executes:
Main: DIR2 = 0 ' pin 2 in input mode PIN2 = 0 ' pin 2 output driver low DEBUG PIN2 ' show state of pin 2 TOGGLE 2 ' toggle pin 2 DEBUG PIN2 ' show state of pin 2 END
Main: DIR2 = 0 ' pin 2 in input mode OUT2 = 0 ' pin 2 output driver low DEBUG ? IN2 ' show state of pin 2 TOGGLE 2 ' toggle pin 2 DEBUG ? IN2 ' show state of pin 2 END
The state of pin 2 doesn't change; it's high (due to the pull-up resistor) before TOGGLE, and it's high (due to the pin being output high) afterward. The point is that TOGGLE works on the OUTS register, which may not match the pin's state when the pin is initially an input. To guarantee that the state actually changes, regardless of the initial input or output mode, do this:
PIN2 = PIN2 ' make output driver match pin state TOGGLE 2 ' then toggle
OUT2 = IN2 ' make output driver match pin state TOGGLE 2 ' then toggle
BASIC Stamp Help Version 2.5.4
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