Typewriter User Manual

7- 16 MC68340 USER’S MANUAL MOTOROLA
C6, C7, C8 ARE LOST
RxD
RECEIVER
ENABLE
D
RxRDY
(SR
0)
FFULL
(SR
1)
RxRDYA
OVERRUN
(SR
4)
RTS
1
STATUS DATA
STATUS DATA
STATUS DATA
CS
RESET BY COMMAND
OPR(0) = 1
C4
C3
C5
C6
C7
C8
C1
C2
NOTES:
1. Timing shown for MR1(7) = 1
2. Timing shown for OPCR(4) = 1 and MR1(6) = 0
3. R = Read
4. C = Received Character
N
R
R
R
R
R
R
R
R
C1
C2
C3
C4
C5
L
OST
STATUS DATA
Figure 7-8. Multidrop Mode Timing Diagram
A transmitted character from the master station consists of a start bit, a programmed
number of data bits, an address/data (A/D) bit flag, and a programmed number of stop
bits. The A/D bit identifies the type of character being transmitted to the slave station. The
character is interpreted as an address character if the A/D bit is set or as a data character
if the A/D bit is cleared. The polarity of the A/D bit is selected by programming bit 2 of the
MR1. The MR1 should be programmed before enabling the transmitter and loading the
corresponding data bits into the transmit buffer.
In multidrop mode, the receiver continuously monitors the received data stream,
regardless of whether it is enabled or disabled. If the receiver is disabled, it sets the
Frees
cale Semiconductor,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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