215
Bit 6—Extended Data Bit (SOL): Bit 6 sets the SO
1
output level. When read, SOL returns the
output level at the SO
1
pin. After completion of a transmission, SO
1
continues to output the value
of the last bit of transmitted data. The SO
1
output can be changed by writing to SOL before or
after a transmission. The SOL bit setting remains valid only until the start of the next transmission.
To control the level of the SO
1
pin after transmission ends, it is necessary to write to the SOL bit at
the end of each transmission. Do not write to this register while transmission is in progress,
because that may cause a malfunction.
Bit 6: SOL
Description
0
Read
SO
1
pin output level is low
(initial value)
Write
SO
1
pin output level changes to low
1
Read
SO
1
pin output level is high
Write
SO
1
pin output level changes to high
Bit 5—Overrun Error Flag (ORER): When an external clock is used, bit 5 indicates the
occurrence of an overrun error. If a clock pulse is input after transfer completion, this bit is set to 1
indicating an overrun. If noise occurs during a transfer, causing an extraneous pulse to be
superimposed on the normal serial clock, incorrect data may be transferred.
Bit 5: ORER
Description
0
[Clearing conditions]
(initial value)
After reading ORER = 1, cleared by writing 0 to ORER
1
[Setting conditions]
Set if a clock pulse is input after transfer is complete, when an external clock
is used
Bits 4 to 2—Reserved Bits: Bits 4 to 2 are reserved; they are always read as 1, and cannot be
modified.
Bit 1—Reserved Bit: Bit 1 is reserved; and cannot be modified. This bit will be read as 0 after a
reset, but its value is undefined at other times.
Bit 0—Start Flag (STF): Bit 0 controls the start of a transfer. Setting this bit to 1 causes SCI1 to
start transferring data.
During the transfer or while waiting for start bit, this bit remains set to 1. It is cleared to 0 upon
completion of the transfer. It can therefore be used as a busy flag.