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(1) Serial I/O shift register 1 (SIO1)
This is an 8-bit register used to carry out parallel/serial conversion and to carry out serial transmission/reception
(shift operation) in synchronization with the serial clock.
SIO1 is set with an 8-bit memory manipulation instruction.
When the value in bit 7 (CSIE10) of serial operating mode register 1 (CSIM1) is 1, writing data to SIO1 starts
the serial operation.
In transmission, data written to SIO1 is output to the serial output (SO1). In reception, data is read from the
serial input (SI1) to SIO1.
RESET input makes SIO1 undefined.
Caution
Do not write data to SIO1 while the automatic transmit/receive function is activated.
(2) Automatic data transmit/receive address pointer (ADTP0)
This register stores the value of (transmit data byte –1) while the automatic transmit/receive function is
activated. As data is transferred/received, it is automatically decremented.
ADTP0 is set with an 8-bit memory manipulation instruction. The high-order 3 bits must be set to 0.
RESET input sets ADTP to 00H.
Caution
Do not write data to ADTP0 while the automatic transmit/receive function is activated.
(3) Serial clock counter
This counter counts the serial clocks to be output and input during transmission/reception to check whether
8-bit data has been transmitted/received.
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CHAPTER 14 SERIAL INTERFACE (SIO1)
Preliminary User's Manual U13420EJ2V0UM00
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