8-12
DSP56309UM/D MOTOROLA
Serial Communication Interface (SCI)
SCI Programming Model
polled to determine if the receive data register is full. If both RIE and RDRF are set, the
SCI requests an SCI receive data interrupt from the interrupt controller.
Receive interrupts with exception have higher priority than normal receive data
interrupts. Therefore, if an exception occurs (i.e., if PE, FE, or OR are set) and REIE is set,
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 RIE.
8.3.1.11
SCR SCI Transmit Interrupt Enable (TIE) Bit 12
The TIE bit is set to enable the SCI transmit data interrupt. If TIE is cleared, transmit data
interrupts are disabled, and the transmit data register empty (TDRE) bit in the SCI status
register must be polled to determine if the transmit data register is empty. If both TIE
and TDRE are set, the SCI requests an SCI transmit data interrupt from the interrupt
controller. Either a hardware RESET signal or a software RESET instruction clears TIE.
8.3.1.12
SCR Timer Interrupt Enable (TMIE) Bit 13
The TMIE bit is set to enable 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.
8.3.1.13
SCR Timer Interrupt Rate (STIR) Bit 14
The STIR bit 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 insure proper operation of the
timer, STIR must not be changed during timer operation (i.e., if TMIE = 1).
8.3.1.14
SCR SCI Clock Polarity (SCKP) Bit 15
The SCKP bit 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
Содержание DSP56309
Страница 25: ...xxii DSP56309UM D MOTOROLA Figure D 25 Port E Registers PCRE PRRE PDRE D 39 ...
Страница 30: ...MOTOROLA DSP56309UM D 1 1 SECTION 1 DSP56309 OVERVIEW ...
Страница 47: ...1 18 DSP56309UM D MOTOROLA DSP56309 Overview DSP56309 Architecture Overview ...
Страница 48: ...MOTOROLA DSP56309UM D 2 1 SECTION 2 SIGNAL CONNECTION DESCRIPTIONS ...
Страница 85: ...2 38 DSP56309UM D MOTOROLA Signal Connection Descriptions OnCE JTAG Interface ...
Страница 86: ...MOTOROLA DSP56309UM D 3 1 SECTION 3 MEMORY CONFIGURATION ...
Страница 104: ...MOTOROLA DSP56309UM D 4 1 SECTION 4 CORE CONFIGURATION ...
Страница 124: ...MOTOROLA DSP56309UM D 5 1 SECTION 5 GENERAL PURPOSE I O ...
Страница 125: ...5 2 DSP56309UM D MOTOROLA General Purpose I O 5 1 INTRODUCTION 5 3 5 2 PROGRAMMING MODEL 5 3 ...
Страница 128: ...MOTOROLA DSP56309UM D 6 1 SECTION 6 HOST INTERFACE HI08 ...
Страница 166: ...MOTOROLA DSP56309UM D 7 1 SECTION 7 ENHANCED SYNCHRONOUS SERIAL INTERFACE ESSI ...
Страница 212: ...MOTOROLA DSP56309UM D 8 1 SECTION 8 SERIAL COMMUNICATION INTERFACE SCI ...
Страница 241: ...8 30 DSP56309UM D MOTOROLA Serial Communication Interface SCI GPIO Signals and Registers ...
Страница 242: ...MOTOROLA DSP56309UM D 9 1 SECTION 9 TRIPLE TIMER MODULE ...
Страница 269: ...9 28 DSP56309UM D MOTOROLA Triple Timer Module Timer Operational Modes ...
Страница 270: ...MOTOROLA DSP56309UM D 10 1 SECTION 10 ON CHIP EMULATION MODULE ...
Страница 302: ...MOTOROLA DSP56309UM D 11 1 SECTION 11 JTAG PORT ...
Страница 369: ...C 22 DSP56309UM D MOTOROLA DSP56309 BSDL Listing ...
Страница 370: ...MOTOROLA DSP56309UM D D 1 APPENDIX D PROGRAMMING REFERENCE ...
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