104. I am having problems with interfacing stuff to the GPIO pins and things.
i.e. a Hardware only take on this question
4. LOGIC LEVEL PROBLEMS (WITH LCDs, UARTS, AND OTHER LOGIC DEVICES)
The output levels of the Pi's GPIO are either nearly 0V, or nearly 3.3V. For most modern logical devices, a logic high of 3.3V is enough, but there are exceptions. For example, many 16x2 character LCDs use either the KS0066 or the HD44780 LCD controller: when fed with 5V, these ICs need at least 3.8V, and so only giving them 3.3V may not register reliably as a logic high, resulting in garbled characters, or even the inability to control the LCD at all.
It is possible to level shift the 3.3V GPIO signals to approximately 5V, but you need at least six shifter levels. An easier solution is to lower the voltage the LCD runs off: instead of 5V, feed it 4V. The LCD controller will work happily with 4V, and the needed input level will go down. One simple way to drop the voltage is by simply adding a diode between the 5V supply, and the LCD's IC power-supply pin (Vcc). Almost any diode will do, but we recommend a 1N4148.
The logic level problem may also affect other digital inputs, like shift registers: we recommend always checking the datasheet of the device to see if its Voltage Input High (VIH) is lower than 3.3V.
ricl : F/gamma = ma : Law ii(a) : https://climatedatablog.wordpress.com/2016/01/02/an-energy-challenge-2016/ #AnEnergyChallenge2016