Usart 8251A - Sanyo MBC-550 Series User Manual

USART 8251A
8251A is a combination device operating in the double
buffer mode. Input to output form the RS-232C interface
board is performed by this USART.
The USART is intialized to one start bit, eight data
bits, no parity, and one stop bit. It operates at a
transmission rate of 1200 bits/sec (determined by timer
counter 2) in the asynchronous mode.
Send/receive clock
8253 OUT2
Output data
buffet
RS-232C
28H
Input data
buffer
Command
2AH
status
Rx Tx
ROY
ROY
8259A IR2
Mark
space
\ ar / °° x «x ■» n
ft
:
=e 0 ^ , e ce: ; ; r Lr_Lr~Ln_n_n_r
lf
i_n_n_jn_
Oc Os Da Dj D? Oi DO
07
RX
1,
SYM n m
D5R pjj ft 01
ROY ROY
•I' it transmit data Puller a empt i
-------- C//n<o»n Id R* ROY pm
]
Conform to T« EMRTYpm
T rl Htcixi (]«ti it m pari* t error Clear thittii mth £R corr*rr.arri. USART
OP««le<n nOt atlected
'f it n«*t data n marred Pelore CRU r Rewree data alter
r*RT operation
eadt
•erred to data Poller, this P't d cleared Py £R
not al'ected
■1 is tranj
Yritn a>encr*o»rut system. T it no stop P i d detected elm da'a cPetecters
tn.sort d cleared Py CRcommard. USAHT operetmn eni allected
Conform (rj S YNOl T/BO pm
J T rl l^R p.n n l \ ff OGR pm .1
5-32