When set the Gpio to output, the up and down exactly what to do with, I write to a pin 1, whether on or drop-down can output 1, so you can literally configuration?

CodePudding user response:

Beginner, don't know much about, will not require an external circuit through resistance and other devices connected power supply or the ground, to the port to provide suitable level?

CodePudding user response:

GPIO output can be divided into, push-pull output, open collector output, open drain output, and the drain in the open collector output open, need to pull resistance, can the pull-up resistor in external chip, can also be initialized GPIO configuration, push-pull output, pull down on the do not have what meaning,

CodePudding user response:

First understand the output capacity
Also 5 v, some 5 v can drive motor racing, some light bulbs, have what can't do anything, can only use voltmeter measure 5 v, there is a load (such as light a light bulb) voltage drop down immediately,
General IO, can go out current is small, pull up resistors in current is big, and can be easily after increasing output current

CodePudding user response:

Should be see you need high level or low level effectively, pull up and down is to port a certain state,

CodePudding user response:

Pull up and down is to maintain and ensure the state when the external release if external input larger internal pull up and down is trivial,