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CHAPTER 17 SERIAL INTERFACE CHANNEL 1
(1) Serial I/O shift register 1 (SIO1)
This 8-bit register converts parallel data into serial data, and transmits/receives serial data (shift operation)
in synchronization with the serial clock.
SIO1 is set by an 8-bit memory manipulation instruction.
When bit 7 (CSIE1) of the serial operation mode register 1 (CSIM1) is 1, the shift operation is started when
data is written to SIO1.
When data is transmitted the data written to SIO1 is output to the serial output line (SO1). When data is
received, it is read from the serial input line (SI1) to SIO1.
The contents of SIO1 become undefined when the RESET signal is input.
Caution
Do not write data to SIO1 when the automatic transmit/receive operation is performed.
(2) Automatic data transmit/receive address pointer (ADTP)
This register stores a value of (number of transmission data bytes – 1) when the automatic transmit/receive
function is performed. Its contents are automatically decremented when data transmission/reception is
executed.
ADTP is set by an 8-bit memory manipulation instruction. At this time, set the high-order 3 bits to 0.
The contents of this register are set to 00H when the RESET signal is input.
Caution
Do not write data to ADTP when the automatic transmit/receive operation is performed.
(3) Serial clock counter
This counter counts the serial clocks output or input during transmit/receive operation, and checks whether
8-bit serial data has been transmitted/received.
17.3 Registers Controlling Serial Interface Channel 1
The following four types of registers control serial interface channel 1:
Timer clock select register 3 (TCL3)
Serial operation mode register 1 (CSIM1)
Automatic data transmit/receive control register (ADTC)
Automatic data transmit/receive interval specification register (ADTI)
(1) Timer clock select register 3 (TCL3)
This register sets the serial clock of serial interface channel 1.
TCL3 is set by an 8-bit memory manipulation instruction.
This register is set to 88H when the RESET signal is input.
Remark
TCL3 also has a function to set the serial clock of serial interface channel 0 in addition to the function
to set the serial clock of serial interface channel 1.