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4.
Line 4 shows that the contents of the receive buffer are transferred to the data register
after all the bits are received.
5.
Line 5 shows the receive communications line gol.ng into the WBC.
6.
Line 6 shows what the receive buffer would look like after all 22 bits are received.
7.
Line 7 shows the receive flag setting when the receive buffer is transferred to the
data register.
1 DEF 3
_fl _ _ _ _ _ _
2
DEF
1
_fl _ _ _ _ _ _
3
Rec. Clock
4
Transfer Receive
~
Buffer to Data
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Register
5
Receive Line
0
6
Receive Buffer
~
7 Receive Flag
Start
Bit
TRANSMIT OPERATION
1 1 1 0
1 0 1 1 0 1 0 0 0 1 1 0 0 1 0
1 1
' St op
Bit
- - - - - - - - - DATA BITS
------------11..,
Figure 20. WBC Receive Timing Diagram
Assume that the program has put the WBC in the transmit mode, the WBC is in the process of
sending a word out· on the line, and a word is waiting in the data register. When the current
word has been shifted into the line, the WBC will transfer the word in the data register to the
shift register.
At this time, the transmit flag will automatically be set. The 20 bits transferred
into the shift register will automatically be preceded by a start bit and followed by a stop bit
WJ&1J&~~1JCJ ~@----------------
V-28
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