7470_N Datasheet, PDF (261/354 Pages) Renesas Technology Corp – 8-BIT SINGLE-CHIP MICROCOMPUTER 740 FAMILY / 7470 SERIES

APPLICATION
2.4 Serial I/O
(2)Byte specification mode
7470 7471 7477 7478
,, × ×
Outline: Among the 7470/7471 group, transfer is performed for two or more microcomputers by
using the clock synchronous byte specification mode.
Specifications: Transmit side M3747x1
• Synchronous clock: f(XIN)/32
• Port P17 is used as an SRDY signal input pin.
• Port P10 is used as an transmit preparation command signal output pin.
Receive side M3747x2 , M3747x3 , M3747x4
• Synchronous clock: External clock
• SARDY signal output
• Port P10 is used as an transmit preparation command signal output pin.
Figure 2.4.4 shows an example of connections and Figure 2.4.5 and 2.4.6 show an example of
control procedure.
Transmit side (M3747x1)
Serial I/O mode register
0 00011 10
• Set port P17 as an input
• Connect a pull-up transistor to port P1 7
• Set port P10 as an output
(Port P10: Transmit preparation
command signal)
P17
CLK
SOUT P10
SARDY
CLK
Serial data
Transmit/receive preparation command signal
SRDY(SARDY) CLK SIN
P10
• Set port P10 as an input
(Port P10: Transmit/receive preparation
command signal)
• Set port P14 as an input
SRDY(SARDY) CLK SIN
P10
• Set port P10 as an input
(Port P10: Transmit/receive preparation
command signal)
• Set port P14 as an input
SRDY(SARDY) CLK SIN P10
• Set port P10 as an input
(Port P10: Transmit/receive preparation
command signal)
• Set port P14 as an input
Serial I/O mode register
1 1111 000
Serial I/O mode register
1 1111 000
Serial I/O mode register
1 11110 00
Byte counter (Initial value) = 0
Receive side 1 (M3747x 2)
Byte counter (Initial value) = 1
Receive side 2 (M3747x 3)
Byte counter (Initial value) = 2
Receive side 3 (M3747x 4)
Fig. 2.4.4 Example of connections [Byte specification mode, 7470/7471 group]
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7470/7471/7477/7478 GROUP USER’S MANUAL