Specifications

CY8C21123/CY8C21223/CY8C21323
Document Number: 38-12022 Rev. *Y Page 41 of 46
serial 1. Pertaining to a process in which all events occur one after the other.
2. Pertaining to the sequential or consecutive occurrence of two or more related activities in a single device or
channel.
settling time The time it takes for an output signal or value to stabilize after the input has changed from one
value to another.
shift register A memory storage device that sequentially shifts a word either left or right to output a stream of
serial data.
slave device A device that allows another device to control the timing for data exchanges between two
devices. Or when devices are cascaded in width, the slave device is the one that allows another
device to control the timing of data exchanges between the cascaded devices and an external
interface. The controlling device is called the master device.
SRAM An acronym for static random access memory. A memory device where you can store and
retrieve data at a high rate of speed. The term static is used because, after a value is loaded into an SRAM cell,
it remains unchanged until it is explicitly altered or until power is removed from the device.
SROM An acronym for supervisory read only memory. The SROM holds code that is used to boot the
device, calibrate circuitry, and perform Flash operations. The functions of the SROM may be
accessed in normal user code, operating from Flash.
stop bit A signal following a character or block that prepares the receiving device to receive the next
character or block.
synchronous 1. A signal whose data is not acknowledged or acted upon until the next active edge of a clock signal.
2. A system whose operation is synchronized by a clock signal.
tri-state A function whose output can adopt three states: 0, 1, and Z (high-impedance). The function does
not drive any value in the Z state and, in many respects, may be considered to be disconnected
from the rest of the circuit, allowing another output to drive the same net.
UART A UART or universal asynchronous receiver-transmitter translates between parallel bits of data
and serial bits.
user modules Pre-build, pre-tested hardware/firmware peripheral functions that take care of managing and
configuring the lower level Analog and Digital PSoC Blocks. User Modules also provide high
level API (Application Programming Interface) for the peripheral function.
user space The bank 0 space of the register map. The registers in this bank are more likely to be modified during normal
program execution and not just during initialization. Registers in bank 1 are most likely to be modified only during
the initialization phase of the program.
V
DD
A name for a power net meaning "voltage drain." The most positive power supply signal. Usually 5 V or 3.3 V.
V
SS
A name for a power net meaning "voltage source." The most negative power supply signal.
watchdog timer A timer that must be serviced periodically. If it is not serviced, the CPU resets after a specified period of time.
Glossary (continued)