82C52

FN2950 Rev 4.00

Page 4 of 21

November 25, 2015

SDI

25

I

High

SERIAL DATA INPUT: Serial data input to the 82C52 receiver circuits. A Mark (1) is high, and a

Space (0) is low. Data inputs on SDI are disabled when operating in the loop mode or when RST is

true.

DR

26

O

High

DATA READY: A true level indicates that a character has been received, transferred to the RBR, and

is ready for transfer to the CPU. DR is reset on a data READ of the Receiver Buffer Register (RBR)

or when RST is true.

27

High

16) is recommended.

CS0

28

I

Low

CHIP SELECT: The chip select input acts as an enable signal for the RD and WR input signals.

SYMBOL

PIN

NO.

TYPE

ACTIVE

LEVEL

DESCRIPTION