Control Pins

Control Pins¶

Logic Level¶

Logic level is a specific voltage or a state in which a signal can exist. These are often referred to as ON (1 or High) or OFF (0 or Low).

Active Low:
To activate the pin of Active low it need to be connected to ground. If there is a line over the Control pin then it is active Low.

Example:

__
CE

Active High:
To activate the pin of Active High it needs to be connected to the HIGH voltage (usually 3.3V/5V).

TTL Logic Levels¶

VOH:
The Minimum OUTPUT Voltage level a TTL device will provide for a HIGH signal.

VIH:
The Minimum INPUT Voltage level to be considered a HIGH.

VOL:
The Maximum OUTPUT Voltage level a device will provide for a LOW signal.

VIL:
The Maximum INPUT Voltage level to still be considered a LOW.

An example below is baised on a memory module
- CE: the Chip Enable Pin.
- WE: the Write Enable Pin
- OE: the Output Enable Pin
Memory Module Example
CE and CS are normally active high (Need to be connected to high voltage to work).