Mercurial > espworkshop
changeset 1:e558443c8d16
Add section on external LED
| author | Radomir Dopieralski <sheep-devel@sheep.art.pl> |
|---|---|
| date | Wed, 08 Jun 2016 23:15:22 +0200 |
| parents | 5050298bb041 |
| children | 94a51485a7e6 |
| files | external.rst index.rst |
| diffstat | 2 files changed, 38 insertions(+), 0 deletions(-) [+] |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/external.rst Wed Jun 08 23:15:22 2016 +0200 @@ -0,0 +1,37 @@ +External Components +******************* + +Now let's try the same, but not with the build-in LED -- let's connect an +external LED and try to use that. The connection should look like this: + +.. image:: ./images/blink.png + +Note how one leg of the LED is a little bit longer, and the other had a +flattening on the plastic of the LED next to it. The long leg should go to the +plus, and the short one to the minus. We are connecting the LED in opposite way +than the internal one is connected -- between the pin and ``gnd``. That means +that it will shine when the pin is high, and be dark when it's low. + +Also note how we added a resistor in there. That is necessary to limit the +amount of current that is going to flow through the LED, and with it, its +brightness. Without the resistor, the LED would shine very bright for a short +moment, until either it, or the board, would overheat and break. We don't want +that. + +Now, let's try the code:: + + from machine import Pin + import time + + led = Pin(14, Pin.OUT) + for i in range(10): + led.high() + time.sleep_ms(500) + led.low() + time.sleep_ms(500) + +Again, you should see the LED blink 10 times, half a second for each blink. + +This time we used ``time.sleep_ms()`` instead of ``time.sleep()`` -- it does +the same thing, but takes the number of milliseconds instead od seconds as the +parameter, so we don't have to use fractions.