What is meant by active high and active low pin?

Simply put, this just describes how the pin is activated. If it’s an active-low pin, you must “pull” that pin LOW by connecting it to ground. For an active high pin, you connect it to your HIGH voltage (usually 3.3V/5V).

What is active low and high?

In digital circuits when: A signal is ‘active low’ means that signal will be performing its function when its logic level is 0. A signal is ‘active high’ means that signal will be performing its function when its logic level is 1.

Why we use enable pin?

If the device is to be permanently enabled, I would tie the Enable pin to Vcc or Ground, whichever will enable the device – should be no need for pull-up or pull-down resistors. The purpose of an enable pin is to allow disabling the part (or some function of it) when you do not need it.

What is output enable pin?

OE (Output Enable) is an output enable signal and read data is output from a data pin when it is set at low level. The function and name are the same as for OE of the EPROM. Writing is enabled when WE (Write Enable) is set at low level.

What is mean by an active high input?

Active High Input Device This means that it only turns on an output when fed HIGH signals, which are signals above 1/2 of the supply voltage (these are read as logic 1 signals). Any input where the voltage is less than half of the power supply to the AND gate will be interpreted as a LOW signal.

Why are some pins active low?

Active-low allows wired-OR with open collector/drain outputs (you may have noticed that calling it ‘wired-OR’ implies negative logic). CMOS parts (originally 4000 series) were not designed to be TTL compatible and generally have active-high inputs.

What is meant by active high?

An active high device is a device that either outputs a HIGH signal when triggered on or that accepts a high signal as input to turn on. It really depends on whether the device is an input or an output device.

What should the enable pin be connected to?

In many tutorials (e.g. http://playground.arduino.cc/learning/4051 or http://bildr.org/2011/02/cd74hc4067-arduino/) it is recommended to connect the multiplexer’s enable pin to ground. So the IC is “switched on”. When set to high all channels are disabled.

What does Output Enable do?

A control input to an integrated circuit that, depending on the logic level applied to it, either permits or prevents the output of data from the device.

What does high impedance state mean?

Hi-Z (or High-Z or high impedance) refers to an output signal state in which the signal is not being driven. The signal is left open, so that another output pin (e.g. elsewhere on a bus) can drive the signal or the signal level can be determined by a passive device (typically, a pull-up resistor).

What is high device?

What does high mean in electronics?

A “high” is a voltage higher than or equal to the minimum high input voltage (VIH) given in the datasheet.

What happens if the enable pin is too high?

Unless the enable pin is pulled high (logic high, usually 5V from a microcontroller), the section of the IC controlled /activated by the enable pin will not work. It has 2 enable pins.

What is the use of enable pin in a motor?

So enable pin is like a switch to turn on the motor. Unless the enable pin is pulled high(logic high, usually 5V from a microcontroller), the section of the IC controlled /activated by the enable pin will not work. It has 2 enable pins.

What does it mean when a pin is in high impedance?

The idea is that if a pin is in high impedance state, it can be pulled to high or low by an external device without much current flow. You see this kind of thing on bidirectional serial lines, where sometimes a pin is an output and sometimes an input.

What is the difference between pull down and pull up pins?

When a GPIO is configured in repeater mode, the pull-up is enabled when the pin is driven high, and the pull-down is enabled when the pin is driven low. If nothing is driving the pin, the pin will retain its last known state (so I guess “repeater” isn’t just a clever name).