Erik Sjödin wrote: > Yes I know I can destroy my Pi but it is only 35$ :) > > and yes i looked at your circuit but people also say adding resistors > are not always nessesary so I decided to try without according to this > guide: > http://razzpisampler.oreilly.com/ch07.html > > "Each GPIO pin has software configurable pull-up and pull-down > resistors. When using a GPIO pin as an input, you can configure these > resistors so that one or either or neither of the resistors is enabled, > using the optional pull_up_down parameter to GPIO.setup. If this > parameter is omitted, then neither resistor will be enabled." > > It seems like I did forgot to configure the software configurable > resistor on the GPIO. > > Its strange, your circuit defines a 3.3V signal while the description I > used for my recent test only connects between GPIO 18 and ground and > they are both defined as input pins. > I will try your circuit example this week as I assume from reading the > internet is the most reliable and safe way to do it. > > Thanx once more for your time and effort. > > Erik
Hi Erik Sjödin, Some of the pull-up and pull-down resistors are configurable via software, some are physically on the RPi PCB. Have a look at the RPi circuit diagram. Setting the software controllable pull-up and pull-down resistors is not a function you can do from purely from user space and scripts as far as I am aware. You need wiringPi or other libraries or even C. Your comment on the circuit shows you don't understand the function of pull-up and pull-down resistors yet. Keep reading. Don't forget the current limiting resistors as well. If you read all the info on RPi GPIOs you will get all kinds of hacks. The lowest level I accept, is what I have shown, others insist on buffering the IO (good idea for commercial products), some just directly short GPIOs. I suppose you need to decide for yourself what you are comfortable with. regards Greg ------------------------------------------------------------------------ Greg Erskine's Profile: http://forums.slimdevices.com/member.php?userid=7403 View this thread: http://forums.slimdevices.com/showthread.php?t=97803
_______________________________________________ unix mailing list [email protected] http://lists.slimdevices.com/mailman/listinfo/unix
