Agorobots - Thursday plan

Using a switch as input.

Any pin on the PIC can also be used as an input, so that your robot can get information about the world around it. By default, a port B input (the A ports are harder to use because they don't have a default) is at 5 volts, and the corresponding bit in memory will be equal to 1 ("set"). If you connect it to ground, then the bit in memory will change to a 0 ("clear"). Here's how you can read the ports in a program:

	useinput portb,2	; use B2 as an input
	btfss	portb,2		; skip the next line if B2 is "set" (1)
	goto	it_was_clear	; go to a different place if B2 is "clear" (0)

it_was_set
	; ... anything in here will be run if B2 was "set" ...
	goto done_with_test	; this skips the next section

it_was_clear
	; ... anything in here will be run if B2 was "clear" ...

done_with_test
	; ... the rest of your program goes here ...

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