MITSUBISHI MICROCOMPUTERS
38B5 Group
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
31
PRELIMINARY
Notice: This s not a final specification.
Some parametric imits are subject to change.
4. S
RDY1
output signal
The S
RDY1
output is a transmit/receive enable signal which informs
the serial transfer destination that transmit/receive is ready. In the
initial status, when the serial I/O initialization bit (b4) is reset to “0,”
the S
RDY1
output goes to “L” and the S
RDY1
output goes to “H”. After
transmitted data is stored in the serial I/O1 register (address 001B
16
)
and a transmit/receive operation becomes ready, the S
RDY1
output
goes to “H” and the S
RDY1
output goes to “L”. When a transmit/
receive operation is started and the transfer clock goes to “L”, the
S
RDY1
output goes to “L” and the S
RDY1
output goes to “H”.
5. S
RDY1
input signal
The S
RDY1
input signal becomes valid only when the S
RDY1
input
and the S
BUSY1
output are used. The S
RDY1
input is a signal for
receiving a transmit/receive ready completion signal from the serial
transfer destination.
When the internal synchronous clock is selected, input a low level
signal into the S
RDY1
input and a high level signal into the S
RDY1
input in the initial status in which the transfer is stopped.
When an “H” level signal is input into the S
RDY1
input and an “L”
level signal is input into the S
RDY1
input for a period of 1.5 cycles or
more of transfer clock, transfer clocks are output from the S
CLK1
output and a transmit/receive operation is started.
After the transmit/receive operation is started and an “L” level sig-
RDY1
input and an “H” level signal into the
_________
RDY1
input, this operation cannot be immediately stopped.
After the specified number of bits are transmitted and received, the
transfer clocks from the S
CLK1
output is stopped. The handshake
unit of the 8-bit serial I/O and that of the automatic transfer serial
I/O are of 8 bits.
When the external synchronous clock is selected, the S
RDY1
input
becomes one of the triggers to output the S
BUSY1
signal.
To start a transmit/receive operation (S
BUSY1
output: “L,” S
BUSY1
output: “H”), input an “H” level signal into the S
RDY1
input and an “L”
level signal into the S
RDY1
input, and also write transmit data into
the serial I/O1 register.
_________
Fig. 30 S
RDY1
Output Operation
Fig. 31 S
RDY1
Input Operation (internal synchronous clock)
S
RDY1
S
CLK1
Write to serial
I/O1 register
S
RDY1
S
CLK1
S
OUT1