DSP56303 FREESCALE [Freescale Semiconductor, Inc], DSP56303 Datasheet - Page 179

• Manufacturer Part Number: DSP56303
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

.
Freescale Semiconductor
Number
23–17
Bit
16
15
14
13
WOMS
SCKP
23
15
7
Name
SCKP
REIE
STIR
TMIE
—Reserved bit; read as 0; write to 0 for future compatibility.
Bit
RWU
STIR
22
14
6
Reset
Value
Table 8-2. SCI Control Register (SCR) Bit Definitions
0
0
0
0
0
Figure 8-3. SCI Control Register (SCR)
WAKE
TMIE
Reserved. Write to 0 for future compatibility.
Receive with Exception Interrupt Enable
Enables/disables the SCI receive data with exception interrupt. If REIE is cleared, the
receive data with exception interrupt is disabled. If both REIE and RDRF are set, and PE,
FE, and OR are not all cleared, the SCI requests an SCI receive data with exception
interrupt from the interrupt controller. Either a hardware RESET signal or a software
RESET instruction clears REIE.
SCI Clock Polarity
Controls the clock polarity sourced or received on the clock signal (SCLK), eliminating
the need for an external inverter. When SCKP is cleared, the clock polarity is positive;
when SCKP is set, the clock polarity is negative. In Synchronous mode, positive polarity
means that the clock is normally positive and transitions negative during valid data.
Negative polarity means that the clock is normally negative and transitions positive
during valid data. In Asynchronous mode, positive polarity means that the rising edge of
the clock occurs in the center of the period that data is valid. Negative polarity means that
the falling edge of the clock occurs during the center of the period that data is valid.
Either a hardware RESET signal or a software RESET instruction clears SCKP.
Timer Interrupt Rate
Controls a divide-by-32 in the SCI Timer interrupt generator. When STIR is cleared, the
divide-by-32 is inserted in the chain. When STIR is set, the divide-by-32 is bypassed,
thereby increasing timer resolution by a factor of 32. Either a hardware RESET signal or
a software RESET instruction clears this bit. To ensure proper operation of the timer,
STIR must not be changed during timer operation (that is, if TMIE = 1).
Timer Interrupt Enable
Enables/disables the SCI timer interrupt. If TMIE is set, timer interrupt requests are sent
to the interrupt controller at the rate set by the SCI clock register. The timer interrupt is
automatically cleared by the timer interrupt acknowledge from the interrupt controller.
This feature allows DSP programmers to use the SCI baud rate generator as a simple
periodic interrupt generator if the SCI is not in use, if external clocks are used for the SCI,
or if periodic interrupts are needed at the SCI baud rate. The SCI internal clock is divided
by 16 (to match the 1 × SCI baud rate) for timer interrupt generation. This timer does not
require that any SCI signals be configured for SCI use to operate. Either a hardware
RESET signal or a software RESET instruction clears TMIE.
21
13
5
DSP56303 User’s Manual, Rev. 2
SBK
TIE
20
12
4
SSFTD
RIE
19
11
3
Description
WDS2
ILIE
18
10
2
WDS1
SCI Programming Model
TE
17
9
1
WDS0
REIE
RE
16
8
0
8-11