m3819 Renesas Electronics Corporation., m3819 Datasheet - Page 115

• Manufacturer Part Number: m3819
• Description: Mitsubishi 8-bit Single-chip Microcomputer 740 Family / 38000 Series
• Manufacturer: Renesas Electronics Corporation.

2. APPLICATION
Fig. 2.3.23 Connection diagram [Cyclic transmission or reception of block data between microcomputers]
(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
Specifications :
Limitations of the specifications
1. Reading of the reception data and setting of the next transmission data must be completed within the time
2. “Heading adjustive time < interval between blocks” must be satisfied.
3. Although the transmission direction can be switched for the Serial I/O of 3819 group, it cannot be
obtained from “byte cycle – time for transmitting 1-byte data” (in this example, the time taken from generating
of the Serial I/O 1 interrupt request to generating of the next synchronizing clock is 431 s).
switched for some serial I/Os of 740 family including 38000 series (only LSB first). Be sure to check when
deciding specifications.
data between the transmitter and receiver 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.
• Synchronous clock frequency : 131 kHz (f(X
• Byte cycle : 488 s
• Number of bytes for transmission or reception : each 8 byte/block
• Block transmission cycle : 16 ms
• Block transmission period : 3.5 ms
• Interval between blocks : 12.5 ms
• Heading adjustive time : 8 ms
• Transmission direction : LSB first
Master unit
S
S
OUT
CLK
S
IN
3819 Group USER’S MANUAL
Slave unit
IN
S
S
S
CLK
IN
OUT
) = 4.19 MHz is divided by 32)
MITSUBISHI MICROCOMPUTER
2.3 Serial I/O
3819 Group
101