356
•
Bits 1 and 0 (Clock Select 1 and 0 (CKS1 and CKS0)): CKS1 and CKS0 select the internal
clock source of the on-chip baud rate generator. Four clock sources are available:
φ
,
φ
/4,
φ
/16,
and
φ
/64. For further information on the clock source, bit rate register settings, and baud rate,
see section 13.2.8, Bit Rate Register (BRR).
Bit 1: CKS1
Bit 0: CKS0
Description
0
0
System clock (
φ
)
(Initial value)
1
φ
/4
1
0
φ
/16
1
φ
/64
13.2.6
Serial Control Register
The serial control register (SCR) enables the SCI transmitter/receiver, selects serial clock output in
asynchronous mode, enables and disables interrupts, and selects the transmit/receive clock source.
The CPU can always read and write to SCR. SCR is initialized to H'00 by a reset and in standby
mode.
Bit:
7
6
5
4
3
2
1
0
Bit name:
TIE
RIE
TE
RE
MPIE
TEIE
CKE1
CKE0
Initial value:
0
0
0
0
0
0
0
0
R/W:
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
•
Bit 7 (Transmit Interrupt Enable (TIE)): TIE enables or disables the transmit-data-empty
interrupt (TXI) requested when the transmit data register empty bit (TDRE) in the serial status
register (SSR) is set to 1 due to transfer of serial transmit data from TDR to TSR.
Bit 7: TIE
Description
0
Transmit-data-empty interrupt request (TXI) is disabled
(Initial value)
The TXI interrupt request can be cleared by reading TDRE after it has
been set to 1, then clearing TDRE to 0, or by clearing TIE to 0.
1
Transmit-data-empty interrupt request (TXI) is enabled
Содержание HD6417032
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Страница 525: ...490 CK RAS CAS TRp TRc TRcc tRASD1 tRASD2 tCASD3 tCASD2 TRr tCSR Figure 20 18 Self Refresh ...
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