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(7) Use of output/input data semaphore (in synchronous transmission mode only)
Figure 4-9 shows the relationship between the output data semaphore (polling/bit
strobe) and input data semaphore. The shaded parts indicate each of the
semaphore values is 1.
S controller
Outptut data
semaphore
Input data
semaphore
DN611
(8) Precautions in using the input/output data area
• The input data semaphore register is used in both polling mode and bit strobe
mode. In cases where polling type and bit strobe type slave devices are mixedly
present, therefore, set data input/output processing in such a way that processing
in polling mode and bit strobe mode will alternately take place upon its comple-
tion: Polling mode → Bit strobe mode → Polling mode → Bit strobe mode.
• Don't write data in the input data area/input data semaphore register using an
MWRITE instruction.. Otherwise, input data could be destroyed.
• In writing data in the polling output data area/bit strobe output data area using an
MWRITE instruction, be careful of the top address of the area and the size of data
size to be written.
Otherwise, the data in other areas could be destroyed, causing the DN611 and/or
slave devices to malfunction.
6F8C0845
Output data
area write
Output
instructed
"1" written
Completion
of output
"0" written
Output
Input
processing
processing
Figure 4-9 Use of Semaphores in Synchronous Mode
4.2 S Controller Interface Buffer Memory Configuration
Input data
Output data
area read
area write
Output
instructed
"1" written
Completion
of read
"0" written
Completion
of input
"1" written
4
Output
processing
57
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