~ National ~ Semiconductor - Al Kossow's Bitsavers

,--------------------------------------------------------------------------, Z
tn
4.0 Timing Waveforms (Continued)
G)
en
RCVR FIFO First Byte (This Sets RDR)
en
~
SIN'""""\. ~Z
'-/ ~TA (5-8)
2 2
SAMPLE CLOCK - ............... ~Il ~21 ................ i.-..... ....L-............-
TRIGGER LEVEL
INTERRUPT ------------+_'
(FCR6. 7=0. 0)
(FIFO AT OR
~-------_~--ABOVE TRIGGER LEVEL)
---(FIFO BELOW
TRIGGER LEVEL)
...
LSI INTERRUPT -------------"'
(ROLSR) RD. ----------------,.--.....,[
________________-'1
(RORBR) RD.RD-----------..... ___________________
---------~,~--~,~
.....,}-__.I'\...
TL/C/B652-10
RCVR FIFO Bytes Other Than the First Byte (RDR Is Already Set)
SIN~
SAMPLE CLOCK
TIMEOUT OR
I
~
(FIFO AT OR
Z--------""'r'---ABOVE TRIGGER LEVEL)
TRIGGER LEVEL ------ NOTE 2 (FIFO BELOW
INTERRUPT IsINT "'INT TRIGGER LEVEL)
--------. ,
LSI INTERRUPT ---------'
RD.RD------r-~,r-~ __ "--~---
(ROLSR) _____ -+ __ ''--_-'1''''"" __ 1-__ _
RD.RO--~,_ __ ~lr-------~I--~~
(RORBR) __"""'--_________"']1-__.1
PREVIOUS BYTE
READ FROM FIFO
TLlC/8652-11
Receiver Ready (Pin 29) FCRO = 0 or FCRO = 1 and FCR3 = 0 (Mode 0)
RD. RO
(RORBR) -------!i 'i-------I'~~~,'--
SIN~
(FIRST BYTE) ../'STOP '--
Note 1: This is the reading of the last byte in the FIFO.
SAMPLE CLK
----tk
__....L~-...&.I_
s----~
NOTE 2
Note 2: If FCRO ~ 1, then tSINT ~ 3 RCLKs. For a timeout interrupt, IsINT ~ 8 RClKs.
TUC/8652-12
4·43