719 bytes added,
00:51, 2 May 2015 =Raspberry pi (CMOS <- TTL level voltage attenuation)=
The "level converter" in this case is only needed to convert from 5V to 3V3 levels, and can consist of a simple voltage divider. the 3V3 level from a CMOS output needs no conversion for most 5V inputs.
You can create a simple attenuator to 3V by using a top 2K2 (2.2k) and a bottom 3K3 resistor, it will work even at high speeds, because the GPIO input is high impedance and its capacitance is relatively low, so the signal isn't degraded much.[https://www.raspberrypi.org/forums/viewtopic.php?f=2&t=5219]
2K2
5V in ——/////—+— 3V out
3K3 |
GND —–/////—-
=Liens divers=
http://bit.ly/lf1XQY
http://bit.ly/lE5NaZ