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When the clock source is an external clock (SBT0 pin input):
•
Set the SC0SBTM flag of the SC0MD3 register.
•
Set bit 2 of the P0DIR register to input mode.
•
Set the P0PLU register, if necessary.
(7)
Select the SC0SBOM flag of the SC0MD3 register.
(8)
Select the SC0IOM flag of the SC0MD3 register.
(9)
Select serial communication by setting the SC0SBOS flag of the
SC0MD3 register to "1."
(10)
Set transmit data to serial interface 0 transmit/receive shift register
(SC0TRB). This will start the serial transmission.
(11)
When serial transmission begins, the SC0BSY flag of the SC0CTR register
is set to "1," indicating that a serial transfer is in progress.
(12)
When the serial transmission has completed, the SC0BSY flag of the
SC0CTR register is cleared to "0" and the SC0 transfer complete interrupt
request flag is set to "1." The SC0TRI flag of SC0MD1 register 1 is cleared
to "0."
After the transfer is complete, the transfer bit count in the
SC0LNG2 to 0 flags of the SC0MD0 register will be changed.
Except in an 8-bit transfer, reset the transfer bit count at the
time of the next transmission.
When switching from transmission to reception, set the
SC0SBOS flag of the SC0MD3 register to "0" and then set
the SC0SBIS flag to "1." Do not change both of these flags at
the same time.
The SC0SBTS flag of the SC0MD3 register must be set to "1"
before the SC0SBOS flag of the SC0MD3 register is set to
"1."
Chapter 5 Serial Functions
When the serial port is enabled
and the SC0CE1 to 0 flags of
the SC0MD0 register are
changed, the transfer bit count
in the SC0LNG2 to 0 flags of
the SC0MD0 register may be
incremented.
Enabling the start condition
drives the SBO0 pin high for a
fixed time interval (1/2 the
clock source cycle) after the
transmission is completed. If
the start condition is disabled,
the SBO0 pin will remain at the
value of the of the last data bit.
If the SC0IOM flag of the
SC0MD3 register is set for a
pin connection, the SBI0 pin
can be used as a port. The
SBO0 pin receives data during
the input mode and transmits
data during the output mode.
The SC0LNG2 to 0 flags
change at the opposite edge of
the transmit data output edge.
Serial interface 0 begins
operation when the SC0SBOS
flag or the SC0SBIS flag is set
to "1." Set the SC0SBOS flag
or the SC0SBIS flag after all
conditions have been set.
Synchronous Serial Interface
95
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