![](http://datasheet.mmic.net.cn/280000/M38023M1D512SP_datasheet_16084972/M38023M1D512SP_100.png)
APPLICATION
2.3 Serial I/O
2-43
3802 GROUP USER’S MANUAL
(3) Cyclic transmission or reception of block data (data of a specified number of bytes)
between microcomputers
[without using an automatic transfer]
Outline :
When a clock synchronous serial I/O is used for communication, synchronization of the clock
and the data between the transmitting and receiving sides may be lost because of noise
included in the synchronizing clock. Thus, it is necessary to be corrected constantly. This
“heading adjustment” is carried out by using the interval between blocks in this example.
Fig. 2.3.31 Connection diagram [Cyclic transmission or reception of block data between
microcomputers]
S
CLK
Master unit
S
CLK
Slave unit
Note:
Use S
OUT
and S
IN
instead of T
X
D and R
X
D in the serial I/O2.
T
X
D
R
X
D
T
X
D
R
X
D
Specifications :
The serial I/O1 is used (clock synchronous serial I/O is selected).
Synchronous clock frequency : 131 kHz (f(X
IN
) = 4.19 MHz is divided by 32)
Byte cycle: 488 μs
Number of bytes for transmission or reception : 8 byte/block
Block transfer cycle : 16 ms
Block transfer period : 3.5 ms
Interval between blocks : 12.5 ms
Heading adjustive time : 8 ms
Limitations of the specifications
1. Reading of the reception data and setting of the next transmission data must be completed
within the time obtained from “byte cycle – time for transferring 1-byte data” (in this example,
the time taken from generating of the Serial I/O1 receive interrupt request to generating of the
next synchronizing clock is 431 μs).
2. “Heading adjustive time < interval between blocks” must be satisfied.