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ML671000 User’s Manual
Chapter 9
Serial Communication Interface (SCI)
9-5
9.2.
Detailed Control Register Descriptions
9.2.1.
SCI Transmit Control Register (STCON)
This 8-bit read/write register controls SCI transmit operation.
After a system reset, the contents are 0x00.
Always wait for current transmit operations to terminate before modifying the contents of this
register. Modification in the middle of such operations interferes with not only the current operation,
but subsequent operations as well.
7654
3210
STNIE
STMIE
STODD
STPEN
STSTB
/STSLV
-STLN
STMOD
Dashes indicate nonexistent bits. Reading one returns “0” in that position.
Figure 9-2
SCI Transmit Control Register (STCON)
■ Bit Descriptions
STNIE:
“0” to disable; “1” to enable
This bit controls interrupt requests when the transmit operation is complete.
Writing “0” to this bit means that completion of the transmit operation does not
produce an interrupt request to the interrupt controller.
STMIE:
“0” to disable; “1” to enable
This bit controls interrupt requests when the transmit buffer is empty. Writing “0” to
this bit means that exhausting the transmit buffer does not produce an interrupt
request to the interrupt controller.
STODD:
“0” for even; “1” for odd
This bit specifies the logic of the parity bits added to the transmit data. It is ignored,
however, when the STPEN bit is “0” (no parity) or the STMOD bit is “1” (CSI
mode).
STPEN:
“0” to disable; “1” to enable
This bit controls the parity bit added to the transmit data. It is ignored, however,
when the STMOD bit is “1” (CSI mode).
STSTB/STSLV:
“0” for 2 stop bits or master mode; “1” for 1 stop bit or slave mode
The name and function of this bit differs with the SCI operation mode.
In ASI mode, it is STSTB, which specifies the number of stop bits.
In CSI mode, it is STSLV, which specifies the operation mode. As master, the serial
communications interface generates, for output to the TXC pin, the shift clock for
synchronizing transmit data. As slave, the serial communications interface takes the
shift clock from the TXC pin.
STLN:
“0” for 8 bits; “1” for 7
This bit specifies the word length for transmit data.
STMOD: “0” for ASI; “1” for CSI
This bit specifies the operation mode for transmitting.