113
Serial I/O2
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Figure 97. S
RDY2
Output Operation
Figure 98. S
RDY2
Input Operation
Serial operation used S
RDY2
output
Internal clock
S
RDY2
(output)
"H"
"L"
Tc
Tc : Internal synchronous clock is selected by bits 5 to 7 of address 0348
16
D
0
D
1
D
2
D
3
D
4
D
5
D
6
D
7
CLK2i
(i = 1, 2)S
S
OUT2
Operation mode
Transfer clock
: 8-bit serial I/O mode
: Internal synchronous clock
"1"
"0"
Serial transfer status flag
(bit 5 at address 0344
16
)
Serial operation used S
RDY2
input
Internal clock
"1"
"0"
S
RDY2
(input
)
"H"
"L"
Tc
Tc : Internal synchronous clock is selected by bits 5 to 7 of address 0348
16
D
0
D
1
D
2
D
3
D
4
D
5
D
6
D
7
1.5 cycle or more
CLK2i
(i = S
S
OUT2
Operation mode
Transfer clock
: 8-bit serial I/O mode
: Internal synchronous clock
Serial transfer status flag
(bit 5 at address 0344
16
)
(4) S
RDY2
output signal
The S
RDY2
output is a transmit/receive enable signal which informs the serial transfer destination that
transmit/receive is ready. In the initial status[serial I/O initialization bit (bit 4 of address 0342
16
) = “0” ],
the S
RDY2
output goes to “L” (or the S
RDY2
output goes to “H”). When the transmitted data is written to
the serial I/O2 register (address 0346
16
), the S
RDY2
output goes to “H” (or the S
RDY2
output goes to
“L”). When a transmit/receive operation is started and the transfer clock goes to “L”, the S
RDY2
output
goes to “L” (or the S
RDY2
output goes to “H”).
(5) S
RDY2
input signal
The S
RDY2
input is a signal for receiving a transmit/receive ready completion signal from the serial
transfer destination. The S
RDY2
input signal becomes valid only when the S
RDY2
input and the S
BUSY2
output are used.
When the internal synchronous clock is selected, input a “L” level signal into the S
RDY2
input (or a “H”
level signal into the S
RDY2
input) in the initial status[serial I/O initialization bit (bit 4 of address 0342
16
)
= “0” ]. When a “H” level signal is input into the S
RDY2
input (or a “L” level signal is input into the S
RDY2
input) for a period of 1.5 cycles or more of transfer clock, transfer clocks are output from the S
CLK2i (i =
1, 2)
output and a transmit/receive operation is started. When S
RDY2
input is driven “L”
(or S
RDY2
input
is driven “H”)
during transmit/receive operation, the transfer clock being output from S
CLK2i (i = 1, 2)
remains active until after the system finishes sending or receiving the designated number of bits,
without stopping the transmit/receive operation immediately.
The handshake unit of the 8-bit serial I/O is 8 bits, and that of the automatic transfer serial I/O is 8 bits.
When the external synchronous clock is selected, the S
RDY2
input becomes one of the triggers to
output the S
BUSY2
signal. To start a transmit/receive operation (S
BUSY2
output: “L”, (or S
BUSY2
output:
“H”)), input a “H” level signal into the S
RDY2
input (or a “L” level signal into the S
RDY2
input,) and also
write transmit data into the serial I/O2 register (address 0346
16
).